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System Administration Guide
Red Hat Enterprise Linux 4: System Administration Guide Copyright © 2005 Red Hat, Inc.
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rhel-sag(EN)-4-Print-RHI (2005-06-06T17:10U1) Copyright © 2005 by Red Hat, Inc. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, V1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/). Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder. Distribution of the work or derivative of the work in any standard (paper) book form for commercial purposes is prohibited unless prior permission is obtained from the copyright holder. Red Hat and the Red Hat "Shadow Man" logo are registered trademarks of Red Hat, Inc. in the United States and other countries. All other trademarks referenced herein are the property of their respective owners. The GPG fingerprint of the email@example.com key is: CA 20 86 86 2B D6 9D FC 65 F6 EC C4 21 91 80 CD DB 42 A6 0E
Table of Contents
Introduction.......................................................................................................................................... i 1. Changes To This Manual ....................................................................................................... i 2. Architecture-specific Information ......................................................................................... ii 3. Document Conventions ......................................................................................................... ii 4. Activate Your Subscription ................................................................................................... v 4.1. Provide a Red Hat Login........................................................................................ v 4.2. Provide Your Subscription Number ....................................................................... v 4.3. Connect Your System............................................................................................ vi 5. Using the Mouse .................................................................................................................. vi 6. Copying and Pasting Text With X........................................................................................ vi 7. More to Come ...................................................................................................................... vi 7.1. Send in Your Feedback ......................................................................................... vi I. Installation-Related Information .................................................................................................... i 1. Kickstart Installations ........................................................................................................... 1 1.1. What are Kickstart Installations? ........................................................................... 1 1.2. How Do You Perform a Kickstart Installation? ..................................................... 1 1.3. Creating the Kickstart File ..................................................................................... 1 1.4. Kickstart Options ................................................................................................... 2 1.5. Package Selection ................................................................................................ 18 1.6. Pre-installation Script........................................................................................... 19 1.7. Post-installation Script ......................................................................................... 21 1.8. Making the Kickstart File Available .................................................................... 22 1.9. Making the Installation Tree Available ................................................................ 23 1.10. Starting a Kickstart Installation ......................................................................... 24 2. Kickstart Configurator ..................................................................................................... 27 2.1. Basic Configuration ............................................................................................. 27 2.2. Installation Method .............................................................................................. 28 2.3. Boot Loader Options............................................................................................ 30 2.4. Partition Information............................................................................................ 30 2.5. Network Configuration ........................................................................................ 33 2.6. Authentication ...................................................................................................... 34 2.7. Firewall Configuration ......................................................................................... 35 2.8. Display Configuration .......................................................................................... 36 2.9. Package Selection ................................................................................................ 39 2.10. Pre-Installation Script ........................................................................................ 39 2.11. Post-Installation Script....................................................................................... 40 2.12. Saving the File ................................................................................................... 42 3. PXE Network Installations ................................................................................................. 43 3.1. Setting up the Network Server ............................................................................. 43 3.2. PXE Boot Configuration ...................................................................................... 43 3.3. Adding PXE Hosts............................................................................................... 45 3.4. Starting the tftp Server ...................................................................................... 46 3.5. Configuring the DHCP Server ............................................................................. 47 3.6. Adding a Custom Boot Message.......................................................................... 47 3.7. Performing the PXE Installation .......................................................................... 47 4. Diskless Environments........................................................................................................ 49 4.1. Start the tftp Server ........................................................................................... 49 4.2. Configuring the DHCP Server ............................................................................. 49 4.3. Configuring the NFS Server................................................................................. 50 4.4. Finish Configuring the Diskless Environment ..................................................... 50 4.5. Adding Hosts ....................................................................................................... 51 4.6. Booting the Hosts................................................................................................. 51 5. Basic System Recovery....................................................................................................... 53 5.1. Common Problems .............................................................................................. 53
5.2. Booting into Rescue Mode................................................................................... 53 5.3. Booting into Single-User Mode ........................................................................... 56 5.4. Booting into Emergency Mode ............................................................................ 56 II. File Systems .................................................................................................................................. 57 6. The ext3 File System .......................................................................................................... 59 6.1. Features of ext3 .................................................................................................... 59 6.2. Creating an ext3 File System ............................................................................... 59 6.3. Converting to an ext3 File System ....................................................................... 60 6.4. Reverting to an ext2 File System ......................................................................... 60 7. Logical Volume Manager (LVM)........................................................................................ 63 7.1. What is LVM? ...................................................................................................... 63 7.2. What is LVM2? .................................................................................................... 64 7.3. Additional Resources ........................................................................................... 64 8. LVM Configuration ............................................................................................................. 65 8.1. Automatic Partitioning ......................................................................................... 65 8.2. Manual LVM Partitioning .................................................................................... 66 9. Redundant Array of Independent Disks (RAID) ................................................................ 73 9.1. What is RAID?..................................................................................................... 73 9.2. Who Should Use RAID?...................................................................................... 73 9.3. Hardware RAID versus Software RAID.............................................................. 73 9.4. RAID Levels and Linear Support ........................................................................ 74 10. Software RAID Configuration .......................................................................................... 77 10.1. Creating the RAID Partitions ............................................................................. 77 10.2. Creating the RAID Devices and Mount Points .................................................. 80 11. Swap Space ....................................................................................................................... 85 11.1. What is Swap Space? ......................................................................................... 85 11.2. Adding Swap Space ........................................................................................... 85 11.3. Removing Swap Space ...................................................................................... 87 11.4. Moving Swap Space .......................................................................................... 88 12. Managing Disk Storage..................................................................................................... 89 12.1. Standard Partitions using parted ..................................................................... 89 12.2. LVM Partition Management .............................................................................. 94 13. Implementing Disk Quotas ............................................................................................... 97 13.1. Configuring Disk Quotas ................................................................................... 97 13.2. Managing Disk Quotas .................................................................................... 100 13.3. Additional Resources ....................................................................................... 102 14. Access Control Lists ....................................................................................................... 103 14.1. Mounting File Systems .................................................................................... 103 14.2. Setting Access ACLs ....................................................................................... 103 14.3. Setting Default ACLs....................................................................................... 104 14.4. Retrieving ACLs .............................................................................................. 105 14.5. Archiving File Systems With ACLs................................................................. 105 14.6. Compatibility with Older Systems................................................................... 106 14.7. Additional Resources ....................................................................................... 106 III. Package Management .............................................................................................................. 109 15. Package Management with RPM.................................................................................... 111 15.1. RPM Design Goals .......................................................................................... 111 15.2. Using RPM ...................................................................................................... 112 15.3. Checking a Package's Signature ...................................................................... 117 15.4. Impressing Your Friends with RPM ................................................................ 118 15.5. Additional Resources ....................................................................................... 120 16. Package Management Tool .......................................................................................... 121 16.1. Installing Packages........................................................................................... 121 16.2. Removing Packages ......................................................................................... 123 17. Red Hat Network ............................................................................................................ 125
IV. Network-Related Configuration .............................................................................................. 129 18. Network Configuration ................................................................................................... 131 18.1. Overview .......................................................................................................... 132 18.2. Establishing an Ethernet Connection ............................................................... 132 18.3. Establishing an ISDN Connection ................................................................... 133 18.4. Establishing a Modem Connection .................................................................. 135 18.5. Establishing an xDSL Connection ................................................................... 136 18.6. Establishing a Token Ring Connection ............................................................ 138 18.7. Establishing a Wireless Connection ................................................................. 139 18.8. Managing DNS Settings .................................................................................. 141 18.9. Managing Hosts ............................................................................................... 142 18.10. Working with Profiles .................................................................................... 143 18.11. Device Aliases ............................................................................................... 145 18.12. Establishing an IPsec Connection .................................................................. 146 18.13. Saving and Restoring the Network Configuration ......................................... 151 19. Basic Firewall Configuration .......................................................................................... 153 19.1. Security Level Configuration Tool................................................................ 153 19.2. Activating the iptables Service.................................................................... 155 20. Controlling Access to Services ....................................................................................... 157 20.1. Runlevels.......................................................................................................... 157 20.2. TCP Wrappers.................................................................................................. 158 20.3. Services Configuration Tool .......................................................................... 159 20.4. ntsysv............................................................................................................... 160 20.5. chkconfig ...................................................................................................... 161 20.6. Additional Resources ....................................................................................... 161 21. OpenSSH......................................................................................................................... 163 21.1. Why Use OpenSSH?........................................................................................ 163 21.2. Configuring an OpenSSH Server ..................................................................... 163 21.3. Configuring an OpenSSH Client...................................................................... 163 21.4. Additional Resources ....................................................................................... 168 22. Network File System (NFS)............................................................................................ 169 22.1. Why Use NFS? ................................................................................................ 169 22.2. Mounting NFS File Systems ............................................................................ 169 22.3. Exporting NFS File Systems............................................................................ 171 22.4. Additional Resources ....................................................................................... 175 23. Samba.............................................................................................................................. 177 23.1. Why Use Samba? ............................................................................................. 177 23.2. Configuring a Samba Server ............................................................................ 177 23.3. Connecting to a Samba Share .......................................................................... 183 23.4. Additional Resources ....................................................................................... 185 24. Dynamic Host Configuration Protocol (DHCP) ............................................................. 187 24.1. Why Use DHCP? ............................................................................................. 187 24.2. Configuring a DHCP Server ............................................................................ 187 24.3. Configuring a DHCP Client ............................................................................. 192 24.4. Additional Resources ....................................................................................... 193 25. Apache HTTP Server Configuration ............................................................................... 195 25.1. Basic Settings................................................................................................... 195 25.2. Default Settings................................................................................................ 197 25.3. Virtual Hosts Settings ...................................................................................... 202 25.4. Server Settings ................................................................................................. 205 25.5. Performance Tuning......................................................................................... 207 25.6. Saving Your Settings ........................................................................................ 207 25.7. Additional Resources ....................................................................................... 208 26. Apache HTTP Secure Server Configuration ................................................................... 211 26.1. Introduction ...................................................................................................... 211 26.2. An Overview of Security-Related Packages .................................................... 211
26.3. An Overview of Certificates and Security ....................................................... 213 26.4. Using Pre-Existing Keys and Certificates ........................................................ 214 26.5. Types of Certificates ........................................................................................ 214 26.6. Generating a Key ............................................................................................. 215 26.7. Generating a Certificate Request to Send to a CA ........................................... 217 26.8. Creating a Self-Signed Certificate ................................................................... 218 26.9. Testing The Certificate ..................................................................................... 219 26.10. Accessing The Server .................................................................................... 220 26.11. Additional Resources ..................................................................................... 220 27. Authentication Configuration.......................................................................................... 223 27.1. User Information .............................................................................................. 223 27.2. Authentication .................................................................................................. 224 27.3. Command Line Version ................................................................................... 226 V. System Configuration ................................................................................................................ 229 28. Console Access ............................................................................................................... 231 28.1. Disabling Shutdown Via [Ctrl]-[Alt]-[Del]...................................................... 231 28.2. Disabling Console Program Access................................................................. 231 28.3. Defining the Console........................................................................................ 232 28.4. Making Files Accessible From the Console .................................................... 232 28.5. Enabling Console Access for Other Applications ........................................... 233 28.6. The floppy Group .......................................................................................... 234 29. Date and Time Configuration.......................................................................................... 235 29.1. Time and Date Properties................................................................................. 235 29.2. Network Time Protocol (NTP) Properties ....................................................... 236 29.3. Time Zone Configuration ................................................................................. 236 30. Keyboard Configuration.................................................................................................. 239 31. Mouse Configuration ...................................................................................................... 241 32. X Window System Configuration ................................................................................... 243 32.1. Display Settings ............................................................................................... 243 32.2. Display Hardware Settings .............................................................................. 243 32.3. Dual Head Display Settings ............................................................................. 244 33. User and Group Configuration ........................................................................................ 247 33.1. Adding a New User.......................................................................................... 247 33.2. Modifying User Properties............................................................................... 248 33.3. Adding a New Group ....................................................................................... 249 33.4. Modifying Group Properties ............................................................................ 249 33.5. Command Line Configuration ......................................................................... 250 33.6. Explaining the Process ..................................................................................... 253 33.7. Additional Information .................................................................................... 254 34. Printer Configuration ...................................................................................................... 257 34.1. Adding a Local Printer..................................................................................... 258 34.2. Adding an IPP Printer ...................................................................................... 259 34.3. Adding a Remote UNIX (LPD) Printer ........................................................... 260 34.4. Adding a Samba (SMB) Printer ....................................................................... 261 34.5. Adding a Novell NetWare (NCP) Printer......................................................... 262 34.6. Adding a JetDirect Printer ............................................................................... 263 34.7. Selecting the Printer Model and Finishing....................................................... 264 34.8. Printing a Test Page.......................................................................................... 265 34.9. Modifying Existing Printers............................................................................. 266 34.10. Saving the Configuration File ........................................................................ 268 34.11. Command Line Configuration ....................................................................... 268 34.12. Managing Print Jobs ...................................................................................... 270 34.13. Sharing a Printer ............................................................................................ 272 34.14. Additional Resources ..................................................................................... 274 35. Automated Tasks............................................................................................................. 275
35.1. Cron.................................................................................................................. 275 35.2. At and Batch .................................................................................................... 277 35.3. Additional Resources ....................................................................................... 279 36. Log Files ......................................................................................................................... 281 36.1. Locating Log Files ........................................................................................... 281 36.2. Viewing Log Files ............................................................................................ 281 36.3. Adding a Log File ............................................................................................ 282 36.4. Examining Log Files........................................................................................ 283 37. Manually Upgrading the Kernel ..................................................................................... 285 37.1. Overview of Kernel Packages .......................................................................... 285 37.2. Preparing to Upgrade ....................................................................................... 286 37.3. Downloading the Upgraded Kernel ................................................................. 287 37.4. Performing the Upgrade................................................................................... 288 37.5. Verifying the Initial RAM Disk Image ............................................................ 288 37.6. Verifying the Boot Loader ............................................................................... 289 38. Kernel Modules............................................................................................................... 293 38.1. Kernel Module Utilities ................................................................................... 293 38.2. Persistent Module Loading .............................................................................. 295 38.3. Additional Resources ....................................................................................... 295 39. Mail Transport Agent (MTA) Configuration .................................................................. 297 VI. System Monitoring ................................................................................................................... 299 40. Gathering System Information........................................................................................ 301 40.1. System Processes ............................................................................................. 301 40.2. Memory Usage................................................................................................. 303 40.3. File Systems ..................................................................................................... 304 40.4. Hardware.......................................................................................................... 304 40.5. Additional Resources ....................................................................................... 305 41. OProfile ........................................................................................................................... 307 41.1. Overview of Tools............................................................................................ 307 41.2. Configuring OProfile........................................................................................ 308 41.3. Starting and Stopping OProfile ........................................................................ 312 41.4. Saving Data ...................................................................................................... 312 41.5. Analyzing the Data .......................................................................................... 312 41.6. Understanding /dev/oprofile/ ................................................................... 315 41.7. Example Usage ................................................................................................ 316 41.8. Graphical Interface........................................................................................... 316 41.9. Additional Resources ....................................................................................... 318 Index................................................................................................................................................. 321 Colophon.......................................................................................................................................... 333
1. For more general information about system administration. Changes To This Manual This manual has been reorganized for clarity and updated for the latest features of Red Hat Enterprise Linux 4. Special thanks to Steve Dickson for his hard work in helping to complete this chapter. If you need security information. If you need more advanced documentation such as an overview of file systems. If you need help installing Red Hat Enterprise Linux. This manual discusses many intermediate topics such as the following: • • • • • • Setting up a network interface card (NIC) Performing a Kickstart installation Configuring Samba shares Managing your software with RPM Determining information about your system Upgrading your kernel This manual is divided into the following main categories: • • • • • • Installation-Related Reference File Systems Reference Package Management Network Configuration System Configuration System Monitoring This guide assumes you have a basic understanding of your Red Hat Enterprise Linux system. refer to the Red Hat Enterprise Linux Installation Guide. If you are looking for a step-by-step. Special thanks to Arjan van de Ven for his hard work in helping to complete this chapter. An Updated Network File System (NFS) Chapter The Network File System (NFS) chapter has been revised and reorganized to include NFSv4. refer to the Red Hat Enterprise Linux Introduction to System Administration. The Red Hat Enterprise Linux System Administration Guide contains information on how to customize your Red Hat Enterprise Linux system to fit your needs. Some of the changes include: Updated Kernel Modules and Manually Updating the Kernel Chapters The Kernel Modules and the Upgrading the Kernel Manually chapters include updated information in regards to the 2. refer to the Red Hat Enterprise Linux Security Guide. . this is the manual for you.Introduction Welcome to the Red Hat Enterprise Linux System Administration Guide. refer to the Red Hat Enterprise Linux Reference Guide. taskoriented guide for configuring and customizing your system.6 kernel.
certain words are represented in different fonts. This guide contains information about topics for advanced users.com/docs/. the Red Hat Enterprise Linux System Administration Guide for general customization instructions. Document Conventions In this manual. information contained in this manual applies only to the x86 processor and processors featuring the Intel® Extended Memory 64 Technology (Intel® EM64T) and AMD64 technologies. An Updated X Window System Chapter The X Window System chapter has been revised to include information on the X11R6. For example: Use the cat testfile command to view the contents of a file. 3. The Release Notes can be found on the Red Hat Enterprise Linux CD #1. HTML. Note Although this manual reflects the most current information possible. and the Red Hat Enterprise Linux Security Guide for security related instructions.ii An Updated OProfile Chapter Introduction The OProfile chapter has been revised and reorganized to include updated information in regards to the 2. This style should indicate to you that you can type the word or phrase on the command line and press [Enter] to invoke a command. The types of words that are represented this way include the following: command Linux commands (and other operating system commands.com/docs/. where <product> is AS. Before reading this guide. Sometimes a command contains words that would be displayed in a different style on their own (such as file names). and RPM versions of the manuals are available on the Red Hat Enterprise Linux Documentation CD and online at http://www. they are considered to be part of the command. sizes. when used) are represented this way.redhat. 2. Architecture-specific Information Unless otherwise noted. named testfile.8 release developed by the X. . so the entire phrase is displayed as a command. in the current working directory. refer to the Red Hat Enterprise Linux Installation Guide for your respective architecture.6 kernel.redhat. This highlighting is systematic.Org team. PDF. different words are represented in the same style to indicate their inclusion in a specific category. In these cases. you should be familiar with the contents of the Red Hat Enterprise Linux Installation Guide concerning installation issues. For architecture-specific information. and weights. online at http://www. WS. or in the /usr/share/doc/redhat-release-4<product>/ directory after installation. typefaces. or Desktop. Special thanks to Will Cohen for his hard work in helping to complete this chapter. ES. read the Red Hat Enterprise Linux Release Notes for information that may not have been available prior to our documentation being finalized. the Red Hat Enterprise Linux Introduction to System Administration for basic administration concepts.
Example: Select the Require Password checkbox if you would like your screensaver to require a password before stopping. the New Tab option allows you to open multiple shell prompts in the same window. [key] A key on the keyboard is shown in this style. Install the webalizer RPM if you want to use a Web server log file analysis program. application This style indicates that the program is an end-user application (as opposed to system software). computer output Text in this style indicates text displayed to a shell prompt such as error messages and responses to commands. top level of a menu on a GUI screen or window A word in this style indicates that the word is the top level of a pulldown menu. This style indicates that a particular file or directory exists with that name on your system. For example: . The /etc/fstab file contains information about different system devices and file systems. For example: Use Mozilla to browse the Web.bashrc file in your home directory contains bash shell definitions and aliases for your own use. or phrase found on a GUI interface screen or window is shown in this style. paths. [key]-[combination] A combination of keystrokes is represented in this way. the rest of the menu should appear. For example: To use [Tab] completion. Your terminal displays the list of files in the directory that start with that letter. word. and RPM package names are represented this way. Instructions to type in a sequence of commands from a GUI menu look like the following example: Go to Applications (the main menu on the panel) => Programming => Emacs Text Editor to start the Emacs text editor. For example: Click on the Back button to return to the webpage you last viewed. For example: The [Ctrl]-[Alt]-[Backspace] key combination exits your graphical session and returns you to the graphical login screen or the console. For example: The ls command displays the contents of a directory. Examples: The . If you click on the word on the GUI screen. button on a GUI screen or window This style indicates that the text can be found on a clickable button on a GUI screen. type in a character and then press the [Tab] key. For example: Under File on a GNOME terminal. directory names. Text shown in this style indicates that a particular GUI screen or an element on a GUI screen (such as text associated with a checkbox or field). text found on a GUI interface A title.Introduction file name iii File names.
is shown in this style. Tip The directory /usr/share/doc/ contains additional documentation for packages installed on your system. prompt A prompt. In the following example. In other words.html backupfiles logs mail Introduction paulwesterberg. is displayed in this style. In order of urgency. a rose is not a ROSE is not a rOsE. where <version-number> is the version and type of kernel installed on this system. . you must type in the text command at the boot: prompt. In the following example. the changes do not take effect until you restart the DHCP daemon. Examples: $ # [stephen@maturin stephen]$ leopard login: user input Text that the user types. <version-number> is displayed in this style: The directory for the kernel source is /usr/src/kernels/<version-number>/. tip. caution. these items are marked as a note. we use several different strategies to draw your attention to certain pieces of information. text is displayed in this style: To boot your system into the text based installation program. <replaceable> Text used in examples that is meant to be replaced with data provided by the user is displayed in this style. Important If you modify the DHCP configuration file. the contents of the directory) is shown in this style.png reports The output returned in response to the command (in this case.iv Desktop Mail about. important. either on the command line or into a text box on a GUI screen. Additionally. which is a computer's way of signifying that it is ready for you to input something. For example: Note Remember that Linux is case sensitive. or warning.
4. and Knowledgebase If you have forgotten your Red Hat login. and the support documentation included in your subscription. errata and maintenance via Red Hat Network Red Hat technical support resources.com/register/.com/help/forgot_password.html A Red Hat login enables your access to: • • Software updates.redhat. If you follow the prompts during the Setup Agent. If you can not complete registration during the Setup Agent (which requires network access). you can alternatively complete the Red Hat registration process online at http://www.1. you must activate your subscription by registering with Red Hat. Provide a Red Hat Login If you do not have an existing Red Hat login. you can search for your Red Hat login online at: https://rhn. 4. you are prompted to register with Red Hat using the Setup Agent. Activate Your Subscription Before you can access service and software maintenance information. Registration includes these simple steps: • • • Provide a Red Hat login Provide a subscription number Connect your system The first time you boot your installation of Red Hat Enterprise Linux. Removing other partitions could result in data loss or a corrupted system environment.pxt .com/apps/activate/newlogin. documentation. Warning Be careful to remove only the necessary partitions.Introduction v Caution Do not perform routine tasks as root — use a regular user account unless you need to use the root account for system administration tasks.redhat. you can create one when prompted during the Setup Agent or online at: https://www.redhat. you can complete the registration steps and activate your subscription.
Provide Your Subscription Number Your subscription number is located in the package that came with your order. If you are instructed to drag and drop an item on your GUI desktop.) The phrase "drag and drop" may be familiar to you. After the Setup Agent has been completed — Enter the following command from the command line as the root user: • /usr/bin/up2date --register 5. More to Come The Red Hat Enterprise Linux System Administration Guide is part of Red Hat's growing commitment to provide useful and timely support to Red Hat Enterprise Linux users. As new tools and applications are released. (This will be reversed if you have configured your mouse to be used by a left handed person. During the Setup Agent — Check the Send hardware information and Send system package list options when prompted. that will be explicitly stated. There are three ways to connect: 1. 3. go to System Tools. You can provide your subscription number when prompted during the Setup Agent or by visiting http://www. 2. then select Red Hat Network. If you need to use the middle or right mouse button. Connect Your System The Red Hat Network Registration Client helps you connect your system so that you can begin to get updates and perform systems management. 4. if you are instructed to click with the mouse on something. 6. this guide will be expanded to include them. 7. When you have reached the desired location. Using the Mouse Red Hat Enterprise Linux is designed to use a three-button mouse. To paste the text somewhere. Copying and Pasting Text With X Copying and pasting text is easy using your mouse and the X Window System. If you have a two-button mouse. After the Setup Agent has been completed — From Applications (the main menu on the panel).redhat. that means click the left mouse button. If your package did not include a subscription number. you should have selected three-button emulation during the installation process. drag the item by moving the mouse to a new location.3. click and drag your mouse over the text to highlight it. release the mouse button to drop the item. click on something and hold the mouse button down. .2.vi Introduction 4. your subscription was activated for you and you can skip this step. In this document. While continuing to hold down the mouse button. To copy text. click the middle mouse button in the spot where the text should be placed. If you are using threebutton emulation. pressing both mouse buttons at the same time equates to pressing the missing third (middle) button.com/register/.
Be sure to mention the manual's identifier: rhel-sag(EN)-4-Print-RHI (2005-06-06T17:10U1) By mentioning this manual's identifier.Introduction vii 7.com/bugzilla/) against the component rhel-sag. Send in Your Feedback If you find an error in the Red Hat Enterprise Linux System Administration Guide. we would love to hear from you! Please submit a report in Bugzilla (http://bugzilla.1. we know exactly which version of the guide you have. or if you have thought of a way to make this manual better.redhat. If you have found an error. try to be as specific as possible when describing it. If you have a suggestion for improving the documentation. please include the section number and some of the surrounding text so we can find it easily. .
viii Introduction .
................................ Use this part in conjunction with the Red Hat Enterprise Linux Installation Guide to perform any of these advanced installation tasks................................................................ PXE Network Installations... advanced installation options are covered in this manual................... Table of Contents 1.......................... However........................................................................ Diskless Environments.... Kickstart Installations . Kickstart Configurator .............................................................. 27 3................................. Basic System Recovery .......................... 49 5.. This part provides instructions for kickstart (an automated installation technique) and all related tools.......................................................... Installation-Related Information The Red Hat Enterprise Linux Installation Guide discusses the installation of Red Hat Enterprise Linux and some basic post-installation troubleshooting............. 53 .......................................................... 43 4........... 1 2.........................I..................................................................
To answer this need. making it ideal for network and system administrators. 2. Items within the sections do not have to be in a specific order unless otherwise specified. using the Kickstart Configurator application. each identified by a keyword.1. Creating the Kickstart File The kickstart file is a simple text file. First.3. Using kickstart. The Red Hat Enterprise Linux installation program also creates a sample kickstart file based on the options that you selected during installation. The section order is: • • Command section — Refer to Section 1. a system administrator can create a single file containing the answers to all the questions that would normally be asked during a typical installation. Create a kickstart file. Kickstart Installations 1. You must include the required options. What are Kickstart Installations? Many system administrators would prefer to use an automated installation method to install Red Hat Enterprise Linux on their machines. 1. or HTTP. To use kickstart. Create a boot media with the kickstart file or make the kickstart file available on the network.Chapter 1. you must: 1. containing a list of items. Make the installation tree available. 3. Kickstart provides a way for users to automate a Red Hat Enterprise Linux installation. 4. . The %packages section — Refer to Section 1. 1. You can create it by editing a copy of the sample.ks file found in the RH-DOCS directory of the Red Hat Enterprise Linux Documentation CD.5 Package Selection for details. You should be able to edit it with any text editor or word processor that can save files as ASCII text.2. be aware of the following issues when you are creating your kickstart file: • Sections must be specified in order.4 Kickstart Options for a list of kickstart options. a local hard drive. FTP. How Do You Perform a Kickstart Installation? Kickstart installations can be performed using a local CD-ROM. Red Hat created the kickstart installation method. or via NFS. This installation method can support the use of a single kickstart file to install Red Hat Enterprise Linux on multiple machines. It is written to the file /root/anaconda-ks. Kickstart files can be kept on a single server system and read by individual computers during the installation. or writing it from scratch.cfg. This chapter explains these steps in detail. Start the kickstart installation.
• • Items that are not required can be omitted. Lines starting with a pound sign (#) are treated as comments and are ignored. which can be run after the install. Refer to Section 1. just as the user would be prompted during a typical installation. passwords are normally encrypted and are not shadowed. autostep (optional) Similar to interactive except it goes to the next screen for you. Kickstart Installations The %pre and %post sections — These two sections can be in any order and are not required. use the Kickstart Configurator application.2 • Chapter 1. Kickstart Options The following options can be placed in a kickstart file. a swap partition. In the example commands. the installation continues unattended (unless it finds another missing item). If you prefer to use a graphical interface for creating your kickstart file. a value must be specified after it. 1. It is used mostly for debugging. those items are ignored (note that this includes package selection). For kickstart upgrades.4. Refer to Chapter 2 Kickstart Configurator for details. auth or authconfig (required) Sets up the authentication options for the system. options in brackets ([]) are optional arguments for the command. the following items are required: • • • • • • • • • Language Language support Installation method Device specification (if device is needed to perform the installation) Keyboard setup The upgrade keyword Boot loader configuration If any other items are specified for an upgrade. By default. . One or more of the default partition sizes can be redefined with the part directive. Note If the option is followed by an equals mark (=). Once the answer is given. and an appropriate boot partition for the architecture. Omitting any required item results in the installation program prompting the user for an answer to the related item.7 Post-installation Script for details. autopart (optional) Automatically create partitions — 1 GB or more root (/) partition. It is similar to the authconfig command.6 Pre-installation Script and Section 1.
This option is set in the /etc/ldap. NIS. you must make users' accounts known to this workstation by enabling LDAP. --enableldap Turns on LDAP support in /etc/nsswitch. use this option to specify the name of the LDAP server to use. or Hesiod or by using the /usr/sbin/useradd command to make their accounts known to this workstation. --ldapbasedn= If you specified either --enableldap or --enableldapauth. --krb5realm= The Kerberos 5 realm to which your workstation belongs. --enablenis uses whatever domain it finds on the network. use this option to specify the DN in your LDAP directory tree under which user information is stored.Chapter 1. To use this option. Kerberos itself does not know about home directories. home directories. This option allows LDAP to send encrypted usernames and passwords to an LDAP server before authentication. you must install the nss_ldap package. --nisdomain= NIS domain name to use for NIS services. allowing your system to retrieve information about users (UIDs. shells. If you enable Kerberos. --useshadow or --enableshadow Use shadow passwords. A domain should almost always be set by hand with the --nisdomain= option. --enablekrb5 Use Kerberos 5 for authenticating users.conf file. This enables the pam_ldap module for authentication and changing passwords. using an LDAP directory.conf file. --nisserver= Server to use for NIS services (broadcasts by default).) from an LDAP directory. If you use this option. you must have the nss_ldap package installed. --enablenis Turns on NIS support. you must have the pam_krb5 package installed. Kickstart Installations --enablemd5 3 Use md5 encryption for user passwords. You must also specify a server and a base DN (distinguished name) with --ldapserver= and --ldapbasedn=. --enableldaptls Use TLS (Transport Layer Security) lookups. By default. You must also specify a server and a base DN with --ldapserver= and --ldapbasedn=.conf. UIDs. etc. or shells. --enableldapauth Use LDAP as an authentication method. --ldapserver= If you specified either --enableldap or --enableldapauth. This option is set in the /etc/ldap. . To use this option.
UIDs. This server handles password changing and other administrative requests. --enablehesiod Enable Hesiod support for looking up user home directories. --krb5adminserver= The KDC in your realm that is also running kadmind.group". or shells. and shells. More information on setting up and using Hesiod on your network is in /usr/share/doc/glibc-2. or Hesiod or by using the /usr/sbin/useradd command to make their accounts known to the workstation. so the LHS and RHS usually begin with periods. and various other items. --smbservers= The name of the server(s) to use for SMB authentication. except jim. separate their names with commas (. --smbworkgroup= The name of the workgroup for the SMB servers.hesiod. which is included in the glibc package. Kickstart Installations The KDC (or KDCs) that serve requests for the realm. which should resolve to a TXT record that looks like what his passwd entry would look like (jim:*:501:501:Jungle Jim:/home/jim:/bin/bash).passwd<LHS><RHS>. UIDs.conf. separate the names with commas (. the situation is identical. --enablesmbauth Enables authentication of users against an SMB server (typically a Samba or Windows server). If you enable SMB. SMB authentication support does not know about home directories.group<LHS><RHS> would be used.uid" a CNAME for "jim. set in /etc/hesiod.conf. For groups.passwd".gid" a CNAME for "jim. To specify more than one server. To use this option.x. and "501. . similar to LDAP's use of a base DN.).4 --krb5kdc= Chapter 1. set in /etc/hesiod.). --hesiodlhs The Hesiod LHS ("left-hand side") option. Tip To look up user information for "jim". If you have multiple KDCs in your realm. NIS. groups.x/README. This server must be run on the master KDC if you have more than one KDC. This option is used by the Hesiod library to determine the name to search DNS for when looking up information. similar to LDAP's use of a base DN.] put in front of them when the library determines the name for which to search. you must make users' accounts known to the workstation by enabling LDAP. the Hesiod library looks up jim. Looking up users and groups by number is handled by making "501. Note that the LHS and RHS do not have periods [. Hesiod is an extension of DNS that uses DNS records to store information about users. --hesiodrhs The Hesiod RHS ("right-hand side") option. you must have the pam_smb package installed. This option is used by the Hesiod library to determine the name to search DNS for when looking up information.
The nscd service caches information about users. --all Erases all partitions from the system. For example: bootloader --location=mbr --append="hdd=ide-scsi ide=nodma" --driveorder Specify which drive is first in the BIOS boot order. no partitions are removed. To preserve other boot loaders. To specify multiple parameters. use bootloader --upgrade. By default. This option is required for both installations and upgrades. . prior to creation of new partitions. if GRUB is not the current boot loader. bootloader (required) Specifies how the GRUB boot loader should be installed. partition (installs the boot loader on the first sector of the partition containing the kernel). This should be used to restrict access to the GRUB shell. Caching is especially helpful if you choose to distribute information about users and groups over your network using NIS. or none (do not install the boot loader). LDAP. separate them with spaces. For example: bootloader --driveorder=sda. and various other types of information. Valid values are the following: mbr (the default). This option is only available for upgrades. Kickstart Installations --enablecache 5 Enables the nscd service. then the --onpart command cannot be used on a logical partition. or hesiod. --md5pass= Similar to --password= except the password should already be encrypted. the boot loader is changed to GRUB. --append= Specifies kernel parameters. Note If the clearpart command is used.hda --location= Specifies where the boot record is written. --password= Sets the GRUB boot loader password to the one specified with this option.Chapter 1. preserving the old entries. groups. where arbitrary kernel options can be passed. --upgrade Upgrade the existing boot loader configuration. clearpart (optional) Removes partitions from the system. For upgrades.
For example: --opts="aic152x=0x340 io=11" driverdisk (optional) Driver diskettes can be used during kickstart installations. however. On older systems and some PCI systems.img driverdisk --source=http://path/to/dd. --linux Erases all Linux partitions. This mode is useful on S/390 systems with the x3270 console. the installation program autoprobes for Ethernet and SCSI cards properly. --opts= Options to pass to the kernel module. For example.img driverdisk --source=nfs:host:/path/to/img . a network location can be specified for the driver diskette: driverdisk --source=ftp://path/to/dd. Kickstart Installations Specifies which drives to clear partitions from. driverdisk <partition> [--type=<fstype>] Alternatively. The device command. --none (default) Do not remove any partitions.hdb --all --initlabel Initializes the disk label to the default for your architecture (for example msdos for x86 and gpt for Itanium). Note that multiple options may be passed if they are put in quotes. the following clears all the partitions on the first two drives on the primary IDE controller: clearpart --drives=hda. which tells the installation program to install extra modules. device (optional) On most PCI systems. Any prompts for interaction halts the install. is in this format: device <type> <moduleName> --opts=<options> <type> Replace with either scsi or eth <moduleName> Replace with the name of the kernel module which should be installed. kickstart needs a hint to find the proper devices. It is useful so that the installation program does not ask if it should initialize the disk label if installing to a brand new hard drive. Then you must use the driverdisk command to tell the installation program where to look for the driver disk. You must copy the driver diskettes's contents to the root directory of a partition on the system's hard drive. cmdline (optional) Perform the installation in a completely non-interactive command line mode.6 --drives= Chapter 1.
If access to services running on this machine is needed. --type= File system type (for example. to allow UDP packets on port 1234 through. . separate them by commas. this option is disabled by default. If enabled. you can choose to allow specific services through the firewall. To list more than one device. • --ssh • --telnet • --smtp • --http • --ftp --port= You can specify that ports be allowed through the firewall using the port:protocol format. such as eth0. vfat or ext2). use --trust eth0 --trust eth1. firewall (optional) firewall --enabled|--disabled [--trust=] <device> [--port=] This option corresponds to the Firewall Configuration screen in the installation program: --enabled Reject incoming connections that are not in response to outbound requests. Numeric ports can also be specified explicitly. If not specified. For example. eth1. the The Setup Agent is started the first time the system boots. specify 1234:udp. Kickstart Installations 7 <partition> Partition containing the driver disk. specify imap:tcp. such as DNS replies or DHCP requests. firstboot (optional) firstboot package must be installed. Do NOT use a comma-separated format such as --trust eth0.Chapter 1. --enable Determine whether the Setup Agent starts the first time the system is booted. To specify multiple ports. for example. --disabled Do not configure any iptables rules. to allow IMAP access through your firewall. allows all traffic coming from that device to go through the firewall. <incoming> Replace with one or more of the following to allow the specified services through the firewall. --trust= Listing a device here.
harddrive Install from a Red Hat installation tree on a local drive. keyboard. where anaconda displays a message and waits for the user to press a key before rebooting. The install command and the installation method command must be on separate lines. cdrom Install from the first CD-ROM drive on the system. and networking configuration options in addition to the default ones. if no completion method is specified. refer to the poweroff. harddrive. which must be either vfat or ext2. Kickstart Installations The Setup Agent is not started the first time the system boots. This is the default mode. sdb2).example. • --partition= Partition to install from (such as. and shutdown kickstart options. mouse. For example: nfs --server=nfsserver.com --dir=/tmp/install-tree . This is similar to a manual installation. --reconfig Enable the Setup Agent to start at boot time in reconfiguration mode. install (optional) Tells the system to install a fresh system rather than upgrade an existing system. • --dir= Directory containing the RedHat directory of the installation tree. For installation. nfs. During a kickstart installation. security level. • --dir= Directory containing the RedHat directory of the installation tree. The halt option is roughly equivalent to the shutdown -h command. This mode enables the language. the reboot option is used as default.8 --disable Chapter 1. you must specify the type of installation from cdrom. time zone. root password. For example: harddrive --partition=hdb2 --dir=/tmp/install-tree nfs Install from the NFS server specified. For other completion methods. reboot. • --server= Server from which to install (hostname or IP). or url (for FTP or HTTP installations). halt (optional) Halt the system after the installation has successfully completed.
The same language codes used with lang can be used with langsupport. sg-latin1. se-latin1. trq. For example: url --url http://<server>/<dir> or: url --url ftp://<username>:<password>@<server>/<dir> interactive (optional) Uses the information provided in the kickstart file during the installation. fr-latin1. speakup-lt.2/site-packages/rhpl/keyboard_models. it. sv-latin1.py contains this list and is part of the rhpl package. sk-qwerty. dk. fr-latin0. hu. pt-latin1. la-latin1. ru-cp1251. cz-lat2. slovene. lang (required) also Sets the language to use during installation. uk. the kickstart file should contain the following line: lang en_US The file /usr/share/system-config-language/locale-list provides a list of the valid language codes in the first column of each line and is part of the system-config-language package. . fr_CH. ru1. it2. langsupport (required) Sets the language(s) to install on the system. For example. dk-latin1. sg. a default must be identified. us-acentos Sets system keyboard type. slovene. to set the language to English. de-latin1. fr. Either accept the values by clicking Next or change the values and click Next to continue. de-latin1-nodeadkeys. cf. no. ru_win. sg-latin1. fr-pc. to install and use the French language fr_FR: langsupport fr_FR --default= If language support for more than one language is specified. Here is the list of available keyboards on i386. but allow for inspection and modification of the values given. bg. To install one language. ro_win. fi. Kickstart Installations url 9 Install from an installation tree on a remote server via FTP or HTTP. it-ibm. ru2. jp106. mk-utf. keyboard (required) be-latin1. ua. fi-latin1. speakup. For example. gr. Refer to the autostep command. de. es. cz-us-qwertz. Itanium. You are presented with each screen of the installation program with the values from the kickstart file.Chapter 1. no-latin1. fr_CH-latin1. hu101. specify it. sg. et. sk-querty. to install English and French and use English as the default language: langsupport --default=en_US fr_FR If you use --default with only one language. and Alpha machines: The file /usr/lib/python2. ru. For example. us. dvorak. is-latin1. pl. all languages are installed with the specified language set to the default. br-abnt2. ru-ms.
generic3. genericps/2. If the kickstart installation does not require networking (in other words. mmseries. networking is not configured for the system.01 --size 3000 volgroup myvg pv. and then create the logical volume. HTTP. logimman+.01 logvol / --vgname=myvg --size=2000 --name=rootvol For a detailed example of Section 1. logibm. microsoft. generic3usb. geniusprops/2. none After options. refer to Configures the mouse for the system. Kickstart Installations Create a logical volume for Logical Volume Management (LVM) with the syntax: logvol <mntpoint> --vgname=<name> --size=<size> --name=<name> <options> The options are as follows: --noformat Use an existing logical volume and do not format it. or it is omitted. the installation program attempts to automatically detect the mouse. This procedure works for most modern mice. genericusb. simultaneous clicks on the left and right mouse buttons are recognized as the middle mouse button by the X Window System.2/site-packages/rhpl/mouse. Options are: --device= Device the mouse is on (such as --device=ttyS0).py file. ascii. logitechcc. network (optional) Configures network information for the system. --emulthree If present. msbm. generic3ps/2. thinkingps/2. msintellips/2. or FTP). mousesystems. generic. For example: part pv. alpsps/2. genericwheelps/2. This option should be used if you have a two button mouse. geniusnm. which is part of the rhpl package. logimmanps/2. genericwheelusb. msintelliusb. logimmusb. geniusnmps/2. sun. both in GUI and text modes. . and configures the final. geniusscrollps/2+. atibm. geniusscrollps/2. asciips/2. --useexisting Use an existing logical volume and reformat it.10 logvol (optional) Chapter 1. The network option configures networking information for kickstart installations via a network as well as for the installed system. create the logical volume group. the installation program assumes that the installation should be done over eth0 via a dynamic IP address (BOOTP/DHCP).4. Create the partition first. msintelli. the mouse type may be specified as one of the following: This list can also be found in the /usr/lib/python2. If the mouse command is given without any arguments. mouse (required) logvol in action. thinking. installed system to determine its IP address dynamically. it is not installed over NFS. logimman+ps/2. If the installation does require networking and network information is not provided in the kickstart file. logitech.1 Advanced Partitioning Example. logimman. msnew. mmhittab.
gateway. netmask. since the installation program configures the network to find the kickstart file. bootp and dhcp are treated the same.2. The line for static networking is more complex.0. It defaults to dhcp. the BOOTP method is similar. However.0. You must specify the IP address. As the name implies. requiring a BOOTP server to supply the networking configuration.254 --nameserver=10. As you might guess. be aware of the following two restrictions: • • All static networking configuration information must be specified on one line.255. you cannot wrap lines using a backslash. this information is static and are used during and after the installation.15 --netmask=255. bootp. you can use the kickstart file's %post section (described in Section 1. --nameserver= Primary nameserver. or static. Kickstart Installations --bootproto= 11 One of dhcp. To direct a system to use DHCP: network --bootproto=dhcp To direct a machine to use BOOTP to obtain its networking configuration. use the following line in the kickstart file: network --bootproto=bootp The static method requires that you enter all the required networking information in the kickstart file. You can only specify one nameserver here. .255.2.0.Chapter 1. For example: network --bootproto=dhcp --device=eth0 --ip= IP address for the machine to be installed. --gateway= Default gateway as an IP address. if needed.0 \ --gateway=10. for example. The DHCP method uses a DHCP server system to obtain its networking configuration. as you must include all network configuration information on one line. Note that using --device= is not effective unless the kickstart file is a local file (such as ks=floppy). and nameserver. --nodns Do not configure any DNS server.2. For example: (the "\" indicates that this should be read as one continuous line): network --bootproto=static --ip=10. --netmask= Netmask for the installed system. as an IP address. --device= Used to select a specific Ethernet device for installation.7 Post-installation Script) to add more name servers.1 If you use the static method.
<id> The partition is used for LVM (refer to logvol). --maxsize= The maximum partition size in megabytes when the partition is set to grow. To determine the size of the swap partition automatically. Specify an integer value here such as 500. refer to Section 1. Specify an integer value here.4. use the --recommended option: swap --recommended The minimum size of the automatically-generated swap partition is no smaller than the amount of RAM in the system and no larger than twice the amount of RAM in the system. All partitions created are formatted as part of the installation process unless --noformat and For a detailed example of part in action. . --size= The minimum partition size in megabytes. or up to the maximum size setting. part or partition (required for installs. • pv.1 Advanced Partitioning Example.<id> The partition is used for software RAID (refer to raid). /usr. the installation program prompts the user and asks which installation to upgrade. If more than one Red Hat Enterprise Linux installation exists on the system on different partitions. --grow Tells the partition to grow to fill available space (if any). --noformat Tells the installation program not to format the partition. ignored for upgrades) Creates a partition on the system. Do not append the number with MB. for use with the --onpart command. • raid. Warning --onpart are used. Kickstart Installations Hostname for the installed system. <mntpoint> The <mntpoint> is where the partition is mounted and must be of one of the following forms: • /<path> For example. /.12 --hostname= Chapter 1. /home • swap The partition is used as swap space. and do not append the number with MB.
diagnostic messages appear on virtual console 3. Contact your manufacturer for more information on you system's APM/ACPI abilities. or the partitioning fails. swap. the reboot option is used as default. reboot. ext3. Note If partitioning fails for any reason. The poweroff option is roughly equivalent to the shutdown -p command. --end= Specifies the ending cylinder for the partition. Note The poweroff option is highly dependent on the system hardware in use. --ondisk= or --ondrive= Forces the partition to be created on a particular disk. Valid values are ext2. and vfat. . and ACPI (advanced configuration and power interface) must be able to interact with the system kernel. APM (advanced power management). anaconda displays a message and waits for the user to press a key before rebooting. --asprimary Forces automatic allocation of the partition as a primary partition. It requires that the starting cylinder be specified with --start=. For example. certain hardware components such as the BIOS. which must already exist. if no completion method is specified. Normally during a manual installation. poweroff (optional) Shut down and power off the system after the installation has successfully completed.Chapter 1. --fstype= Sets the file system type for the partition. --start= Specifies the starting cylinder for the partition. --type= (replaced by fstype) This option is no longer available. Kickstart Installations --onpart= or --usepart= 13 Put the partition on the already existing device. It requires that a drive be specified with --ondisk= or ondrive=. and shutdown kickstart options. Use fstype. It also requires that the ending cylinder be specified with --end= or the partition size be specified with --size=. refer to the halt. Specifically. --ondisk=sdb puts the partition on the second SCSI disk on the system. For example: partition /home --onpart=hda1 puts /home on /dev/hda1. For other completion methods. During a kickstart installation.
It also creates three swap partitions.1 Advanced Partitioning Example. and a RAID level 5 for /usr. The reboot option is roughly equivalent to the shutdown -r command.13 For a detailed example of raid in action.4.03 --size=60 --ondisk=sdc swap --size=128 --ondisk=sda swap --size=128 --ondisk=sdb swap --size=128 --ondisk=sdc raid. or 5). refer to Section 1. reboot (optional) Reboot after the installation is successfully completed (no arguments). --fstype= Sets the file system type for the RAID array. The following example shows how to create a RAID level 1 partition for /.12 raid. The <partitions*> (which denotes that multiple partitions can be listed) lists the RAID identifiers to add to the RAID array. 1. and each may only be used once. Valid values are ext2. This command is of the form: raid <mntpoint> --level=<level> --device=<mddevice> <partitions*> <mntpoint> Location where the RAID file system is mounted. swap. Spare drives are used to rebuild the array in case of drive failure. assuming there are three SCSI disks on the system.12 --size=1 --grow --ondisk=sdb raid. part part part part part part part part part raid raid raid. . If a boot partition is present. ext3. Kickstart Installations Assembles a software RAID device.01 raid.14 raid (optional) Chapter 1. the /boot partition must be level 1 and the root (/) partition can be any of the available types.02 raid. the RAID level must be 1 unless a boot partition (/boot) is present.11 --size=1 --grow --ondisk=sda raid. --device= Name of the RAID device to use (such as md0 or md1).03 /usr --level=5 --device=md1 raid.11 raid.02 --size=60 --ondisk=sdb raid. RAID devices range from md0 to md7. one on each drive.13 --size=1 --grow --ondisk=sdc / --level=1 --device=md0 raid. --level= RAID level to use (0. --useexisting Use an existing RAID device and reformat it. If it is /. --spares= Specifies the number of spare drives allocated for the RAID array. and vfat. --noformat Use an existing RAID device and do not format the RAID array. Normally during a manual installation. anaconda displays a message and waits for the user to press a key before rebooting.01 --size=60 --ondisk=sda raid.
poweroff. --disabled Disables SELinux completely on the system. skipx (optional) If present. the reboot option is used as default. and reboot kickstart options. selinux (optional) Sets the system's SELinux mode to one of the following arguments: --enforcing Enables SELinux with the default targeted policy being enforced. shutdown (optional) Shut down the system after the installation has successfully completed. refer to the halt. rootpw (required) Sets the system's root password to the <password> argument. but does not actually enforce the policy. rootpw [--iscrypted] <password> --iscrypted If this is present. For other completion methods. the password argument is assumed to already be encrypted. For complete information regarding SELinux for Red Hat Enterprise Linux. The shutdown option is roughly equivalent to the shutdown command. . poweroff. During a kickstart installation. For other completion methods. The reboot option is the default completion method if no other methods are explicitly specified in the kickstart file. Kickstart Installations 15 Note Use of the reboot option may result in an endless installation loop. depending on the installation media and method. and shutdown kickstart options. refer to the Red Hat SELinux Guide. X is not configured on the installed system. if no completion method is specified.Chapter 1. refer to the halt. Note If the selinux option is not present in the kickstart file. SELinux is enabled and set to --enforcing by default. --permissive Outputs warnings only based on the SELinux policy.
Kickstart Installations Perform the kickstart installation in text mode. if X was installed. This is ignored if --hsync or --vsync is provided. --card= Use specified card.16 text (optional) Chapter 1. the user must configure X manually during the installation. harddrive. or url (for FTP and HTTP) as the location of the installation tree. this option should not be used if X is not installed on the final system. If this argument is not provided. --vsync= Specifies the vertical sync frequency of the monitor. the installation program tries to probe for it automatically. the installation program probes the PCI bus for the card. You must specify one of cdrom. the system assumes the hardware clock is set to UTC (Greenwich Mean) time. Kickstart installations are performed in graphical mode by default. Refer to install for details. this card name should be from the list of cards in /usr/share/hwdata/Cards from the hwdata package. --videoram= Specifies the amount of video RAM the video card has. If no monitor information is provided. Since AGP is part of the PCI bus. Sets the system time zone to <timezone> which may be any of the time zones listed by timezone [--utc] <timezone> --utc If present. AGP cards are detected if supported. . monitor name should be from the list of monitors in also be found on the X Configuration screen of the Kickstart Configurator. The list of monitors can Use specified monitor. upgrade (optional) Tells the system to upgrade an existing system rather than install a fresh system. --monitor= /usr/share/hwdata/MonitorsDB from the hwdata package. xconfig (optional) Configures the X Window System. The list of cards can also be found on the X Configuration screen of the Kickstart Configurator. --hsync= Specifies the horizontal sync frequency of the monitor. timezone (required) timeconfig. The probe order is determined by the PCI scan order of the motherboard. nfs. --noprobe Do not probe the monitor. If this option is not given.
1400x1050. --depth= Specify the default color depth for the X Window System on the installed system. 16. 1280x1024. Kickstart Installations --defaultdesktop= 17 Specify either GNOME or KDE to set the default desktop (assumes that GNOME Desktop Environment and/or KDE Desktop Environment has been installed through %packages).01 logvol / --vgname=myvg --size=2000 --name=rootvol For a detailed example of Section 1. Create the partition first. --useexisting Use an existing volume group and reformat it. and then create the logical volume. Valid values are 640x480. 1024x768. This command should be in the following format: zerombr yes No other format is effective. --resolution= Specify the default resolution for the X Window System on the installed system. refer to If zerombr is specified. zerombr (optional) volgroup in action. any invalid partition tables found on disks are initialized. 1600x1200. 800x600.01 --size 3000 volgroup myvg pv. Be sure to specify a resolution that is compatible with the video card and monitor.Chapter 1. --startxonboot Use a graphical login on the installed system. volgroup (optional) Use to create a Logical Volume Management (LVM) group with the syntax: volgroup <name> <partition> <options> The options are as follows: --noformat Use an existing volume group and do not format it. Be sure to specify a color depth that is compatible with the video card and monitor.4. This destroys all of the contents of disks with invalid partition tables. .1 Advanced Partitioning Example. 24. 1152x864. Valid values are 8. %include Use the %include /path/to/file command to include the contents of another file in the kickstart file as though the contents were at the location of the %include command in the kickstart file. and 32. and yes is its sole argument. For example: part pv. create the logical volume group.
24 raid. raid.4.12 raid swap --fstype swap --device md2 --level=RAID1 raid.22 raid.18 Chapter 1.13 raid /usr --fstype ext3 --device md3 --level=RAID1 raid. and the packages marked optional must be specifically selected even if the group is selected to be installed. 1.01 logvol /var --vgname=sysvg --size=8000 --name=var logvol /var/freespace --vgname=sysvg --size=8000 --name=freespacetouse logvol /usr/local --vgname=sysvg --size=1 --grow --name=usrlocal This advanced example implements LVM over RAID. The installation program defines several groups that contain related packages.23 raid.14 raid pv.14 --size part raid.15 # LVM configuration so that we can resize /var and /usr/local later volgroup sysvg pv. as well as the ability to resize various directories for future growth. Kickstart Installations 1. Note that the Core and Base groups are always selected by default.22 raid. the packages marked default are selected by default if the group is selected. description.xml file on the first Red Hat Enterprise Linux CD-ROM for a list of groups.12 --size part raid.11 raid /safe --fstype ext3 --device md1 --level=RAID1 raid.21 raid.25 # You can add --spares=x raid / --fstype ext3 --device md0 --level=RAID1 raid.25 --size --size --size --size --size 1000 --asprimary 1000 --asprimary 2000 --asprimary 8000 1 --grow 1000 --asprimary 1000 --asprimary 2000 --asprimary 8000 1 --grow --ondrive=hda --ondrive=hda --ondrive=hda --ondrive=hda --ondrive=hda --ondrive=hdc --ondrive=hdc --ondrive=hdc --ondrive=hdc --ondrive=hdc raid. Package Selection Use the %packages command to begin a kickstart file section that lists the packages you would like to install (this is for installations only. and package list. Advanced Partitioning Example logvol kickstart options in action: The following is a single.hdc --initlabel # Raid 1 IDE config part raid. Each group has an id. Here is an example %packages selection: %packages @ X Window System . Packages can be specified by group or by individual package name.24 raid. user visibility value. it is only necessary to list the desired groups and not individual packages. Refer to the RedHat/base/comps. part.21 raid. In most cases. In the package list. and clearpart --drives=hda.1.01 --fstype ext3 --device md4 --level=RAID1 raid.5.13 --size part raid.23 raid. so it is not necessary to specify them in the %packages section. the packages marked as mandatory are always installed if the group is selected. as package selection during upgrades is not supported).11 --size part raid. volgroup. name.15 --size part part part part part raid. integrated example showing the clearpart.
--interpreter /usr/bin/python Allows you to specify a different scripting language. . name service has not been configured at this point. a space. such as Python. such as gnome-desktop. however. You can access the network in the %pre section. one to a line. and then the full group name as given in the comps.xml file. the automated installation pauses and prompts the user. Replace /usr/bin/python with the scripting language of your choice.6.cfg has been parsed. so only IP addresses work. You can also specify which packages not to install from the default package list: -autofs The following options are available for the %packages option: --resolvedeps Install the listed packages and automatically resolve package dependencies. Groups can also be specified using the id for the group. For example: %packages --ignoredeps --ignoremissing Ignore the missing packages and groups instead of halting the installation to ask if the installation should be aborted or continued.Chapter 1. For example: %packages --resolvedeps --ignoredeps Ignore the unresolved dependencies and install the listed packages without the dependencies. This section must be at the end of the kickstart file (after the commands) and must start with the %pre command. Pre-installation Script You can add commands to run on the system immediately after the ks. groups are specified. Note Note that the pre-install script is not run in the change root environment. For example: %packages --ignoremissing 1. Specify individual packages with no additional characters (the dhcp line in the example above is an individual package). If this option is not specified and there are package dependencies. Kickstart Installations @ GNOME Desktop Environment @ Graphical Internet @ Sound and Video dhcp 19 As you can see. starting with an @ symbol.
6.1. . then hds="$hds 'basename $file'" fi done set $hds numhd='echo $#' drive1='echo $hds | cut -d' ' -f1' drive2='echo $hds | cut -d' ' -f2' #Write out partition scheme based on whether there are 1 or 2 hard drives if [ $numhd == "2" ] . then #2 drives echo "#partitioning scheme generated in %pre for 2 drives" > /tmp/part-include echo "clearpart --all" >> /tmp/part-include echo "part /boot --fstype ext3 --size 75 --ondisk hda" >> /tmp/part-include echo "part / --fstype ext3 --size 1 --grow --ondisk hda" >> /tmp/part-include echo "part swap --recommended --ondisk $drive1" >> /tmp/part-include echo "part /home --fstype ext3 --size 1 --grow --ondisk hdb" >> /tmp/part-include else #1 drive echo "#partitioning scheme generated in %pre for 1 drive" > /tmp/part-include echo "clearpart --all" >> /tmp/part-include echo "part /boot --fstype ext3 --size 75" >> /tmp/part-includ echo "part swap --recommended" >> /tmp/part-include echo "part / --fstype ext3 --size 2048" >> /tmp/part-include echo "part /home --fstype ext3 --size 2048 --grow" >> /tmp/part-include fi This script determines the number of hard drives in the system and writes a text file with a different partitioning scheme depending on whether it has one or two drives. Example Here is an example %pre section: %pre #!/bin/sh hds="" mymedia="" for file in /proc/ide/h* do mymedia='cat $file/media' if [ $mymedia == "disk" ] .20 Chapter 1. Instead of having a set of partitioning commands in the kickstart file. include the line: %include /tmp/part-include The partitioning commands selected in the script are used. Kickstart Installations 1.
but you can not resolve IP addresses. Examples Turn services on and off: /sbin/chkconfig /sbin/chkconfig /sbin/chkconfig /sbin/chkconfig --level --level --level --level 345 345 345 345 telnet off finger off lpd off httpd on . This section must be at the end of the kickstart file and must start with the %post command. including a nameserver. you can access the network and resolve IP addresses in the %post section.cfg file. Post-installation Script You have the option of adding commands to run on the system once the installation is complete.conf to the file system that was just installed. Note If you configured the network with static IP information. The following example copies the file /etc/resolv. Thus. the /etc/resolv.conf file has not been completed when the installation executes the %post section. --nochroot Allows you to specify commands that you would like to run outside of the chroot environment. if you are using DHCP.Chapter 1.conf --interpreter /usr/bin/python Allows you to specify a different scripting language.7. performing tasks such as copying scripts or RPMs from the installation media do not work. therefore. If you configured the network for DHCP.conf /mnt/sysimage/etc/resolv. Note The post-install script is run in a chroot environment.7. as the pre-installation script occurs during the second stage of the installation process.1. %post --nochroot cp /etc/resolv. you must specify IP addresses in the %post section. This information must be included for each created ks. This section is useful for functions such as installing additional software and configuring an additional nameserver. 1. You can access the network. Kickstart Installations 21 Note The pre-installation script section of kickstart cannot manage multiple install trees or source media. 1. Replace /usr/bin/python with the scripting language of your choice. such as Python.
cfg kickstart file to the isolinux/ directory. Installations must use CD-ROM or flash memory products for booting. however. 1. For example.8. Creating Kickstart Boot Media Diskette-based booting is no longer supported in Red Hat Enterprise Linux. Add a user to the system: /usr/sbin/useradd bob /usr/bin/chfn -f "Bob Smith" bob /usr/sbin/usermod -p 'kjdf$04930FTH/ ' bob 1. the kickstart file may still reside on a diskette's top-level directory.1. Create the boot image first. therefore -o nolock is required when mounting an NFS mount. Since a CD-ROM is read-only.2:/usr/new-machines /mnt/temp open -s -w -.cfg and must be located in the boot CD-ROM's top-level directory. as most kickstart installations tend to be performed on networked computers.10. the file must be added to the directory used to create the image that is written to the CD-ROM. and then copy the ks. the following transfers a boot image to the pen drive ( /dev/sda) using the dd command: dd if=diskboot.8. However. copy the ks.0.cfg.cfg and must be located in the flash memory's top-level directory. Let us take a more in-depth look at where the kickstart file may be placed. before making the file./mnt/temp/runme umount /mnt/temp Chapter 1. the kickstart file must be named ks. The networkbased approach is most commonly used. Refer to the Red Hat Enterprise Linux Installation Guide for instructions on creating boot media. and must be named ks.img of=/dev/sda bs=1M . To perform a pen-based flash memory kickstart installation. Kickstart Installations Note NFS file locking is not supported while in kickstart mode.iso image file.cfg file. the kickstart file must be named ks. or made available on the network. To perform a CD-ROM-based kickstart installation. Making the Kickstart File Available A kickstart file must be placed in one of the following locations: • • • On a boot diskette On a boot CD-ROM On a network Normally a kickstart file is copied to the boot diskette.22 Run a script named runme from an NFS share: mkdir /mnt/temp mount -o nolock 10.
using it as the kickstart file. An installation tree is a copy of the binary Red Hat Enterprise Linux CD-ROMs with the same directory structure.Chapter 1.0. and it must include configuration information for the machine on which you are attempting to install Red Hat Enterprise Linux. and searches for a particular file. you must have a BOOTP/DHCP server on your network. while the actual files used during the installation are served by the NFS server. the client system mounts that path using NFS. Making the Installation Tree Available The kickstart installation must access an installation tree. The BOOTP/DHCP server provides the client with its networking information as well as the location of the kickstart file. and copies the specified file to the client.redhat.1-kickstart. Making the Kickstart File Available on the Network Network installations using kickstart are quite common. The BOOTP/DHCP server is used to give the client system its networking information.com. If you are performing a CD-based installation.10. The file name the client searches for is: <ip-addr>-kickstart The <ip-addr> section of the file name should be replaced with the client's IP address in dotted decimal notation. then it is interpreted as a path only. insert the Red Hat Enterprise Linux CD-ROM #1 into the computer before starting the kickstart installation. Kickstart Installations 23 Note Creation of USB flash memory pen drives for booting is possible. because system administrators can easily automate the installation on many networked computers quickly and painlessly. Refer to your hardware manufacturer to see if your system supports booting to alternate devices.9.8. Note that you should replace the value after filename with the name of the kickstart file (or the directory in which the kickstart file resides) and the value after next-server with the NFS server name.0. Often. 1. If you do not specify a path or file name. Note that if you do not specify a server name. If the file name returned by the BOOTP/DHCP server ends with a slash ("/"). but is heavily dependent on system hardware BIOS settings.1 would be 10. To perform a network-based kickstart installation. The exact settings required vary depending on the BOOTP/DHCP server you use. the client system attempts an NFS mount of the file's path. then the client system attempts to use the server that answered the BOOTP/DHCP request as its NFS server.10. the approach most commonly used is for the administrator to have both a BOOTP/DHCP server and an NFS server on the local network. these two servers run on the same physical machine. If a kickstart file is specified by the BOOTP/DHCP server.conf file for the DHCP server: filename "/usr/new-machine/kickstart/".2. In this case. . In general. Here is an example of a line from the dhcpd. next-server blarg. but they are not required to. 1. the file name for a computer with an IP address of 10. For example. the client system tries to mount /kickstart from the BOOTP/DHCP server and tries to find the kickstart file using the same <ip-addr>-kickstart file name as described above.
Kickstart Installations If you are performing a hard drive installation. 1. you must boot the system from boot media you have made or the Red Hat Enterprise Linux CD-ROM #1.cfg. and enter a special boot command at the boot prompt. For example. For example. enter the following command at the boot: prompt: linux ks=floppy dd Boot CD-ROM If the kickstart file is on a boot CD-ROM as described in Section 1.cfg Other options to start a kickstart installation are as follows: ks=nfs:<server>:/<path> The installation program looks for the kickstart file on the NFS server <server>.cfg file is located on a vfat or ext2 file system on a diskette and you boot from the Red Hat Enterprise Linux CD-ROM #1. to boot off a boot diskette and use a driver disk. make sure the ISO images of the binary Red Hat Enterprise Linux CD-ROMs are on a hard drive in the computer. as file <path>. If you are performing a network-based (NFS. you must make the installation tree available over the network.cfg on a vfat or ext2 file system on the diskette in .example.cfg.example. Refer to the Preparing for a Network Installation section of the Red Hat Enterprise Linux Installation Guide for details.1 Creating Kickstart Boot Media. if your NFS server is server. insert the CD-ROM into the system. if your HTTP server is server. The installation program looks for the file ks.example.cfg With Driver Disk If you need to use a driver disk with kickstart. enter the following command at the boot: prompt: linux ks=hd:fd0:/ks.24 Chapter 1. To do so. FTP.com and the kickstart file is in the NFS share /mydir/ks. For example. the correct boot command would be ks=http://server.example. CD-ROM #1 and Diskette The linux ks=floppy command also works if the ks. The installation program uses DHCP to configure the Ethernet card.cfg.cfg is the name of the kickstart file): linux ks=cdrom:/ks. or HTTP) installation.com/mydir/ks. The installation program uses DHCP to configure the Ethernet card.10. the correct boot command would be ks=nfs:server. ks=http://<server>/<path> The installation program looks for the kickstart file on the HTTP server <server>.8.com and the kickstart file is in the HTTP directory /mydir/ks. ks=floppy /dev/fd0. An alternate boot command is to boot off the Red Hat Enterprise Linux CD-ROM #1 and have the kickstart file on a vfat or ext2 file system on a diskette. boot the system. Starting a Kickstart Installation To begin a kickstart installation.cfg. and enter the following command at the boot: prompt (where ks. specify the dd option as well.com:/mydir/ks. as file <path>. The installation program looks for a kickstart file if the ks command line argument is passed to the kernel.
ks=file:/<file> The installation program tries to read the file <file> from the file system. . /kickstart/1. where 1. For example. Kickstart Installations ks=floppy:/<path> 25 The installation program looks for the kickstart file on the diskette in /dev/fd0. the boot file provided by DHCP is looked for on the NFS server. By default. The name of the kickstart file is one of the following: • • • If DHCP is specified and the boot file begins with a /. If DHCP is specified and the boot file begins with something other then a /. ks=hd:<device>:/<file> The installation program mounts the file system on <device> (which must be vfat or ext2). use the command ks=nfs:<server>:/<path> ksdevice=eth1 at the boot: prompt.3.cfg). ks If ks is used alone. ks=hd:sda3:/mydir/ks. then the installation program tries to read the file machine being installed. This is normally used if the kickstart file is already on the initrd image.Chapter 1. as file <path>. the bootServer is the same as the DHCP server.4-kickstart. and look for the kickstart configuration file as <file> in that file system (for example.2. no mounts are done. to start a kickstart installation with the kickstart file on an NFS server that is connected to the system through the eth1 device.3. ks=cdrom:/<path> The installation program looks for the kickstart file on CD-ROM. the boot file provided by DHCP is looked for in the /kickstart directory on the NFS server.4 is the numeric IP address of the If DHCP did not specify a boot file. The kickstart file is read from the "bootServer" from the DHCP response as if it is an NFS server sharing the kickstart file. the installation program configures the Ethernet card to use DHCP. ksdevice=<device> The installation program uses this network device to connect to the network.2. as file <path>.
Kickstart Installations .26 Chapter 1.
To start with an existing kickstart file. a three-button mouse can be emulated by selecting Emulate 3 Buttons. Basic Configuration Choose the language to use during the installation and as the default language to be used after installation from the Default Language menu. Probing works for most modern mice. Choose the mouse for the system from the Mouse menu. If this option is selected.1. To start Kickstart Configurator. Kickstart Configurator Kickstart Configurator allows you to create or modify a kickstart file using a graphical user interface. you can select File => Preview at any time to review your current selections. simultaneously clicking the left and right mouse buttons are recognized as a middle mouse button click. If the system has a two-button mouse. If No Mouse is selected. If Probe for Mouse is selected. no mouse is configured. the installation program tries to automatically detect the mouse. you must be running the X Window System.Chapter 2. As you are creating a kickstart file. 2. select File => Open and select the existing file. select Applications (the main menu on the panel) => System Tools => Kickstart. or type the command /usr/sbin/system-config-kickstart. Select the system keyboard type from the Keyboard menu. . To use Kickstart Configurator. Basic Configuration Figure 2-1. so that you do not have to remember the correct syntax of the file.
The language selected from the Default Language pulldown menu is used by default after installation. If the encryption option is selected. To select this type of installation. select the Perform installation in interactive mode option. Kickstart Configurator From the Time Zone menu.28 Chapter 2. The second field is to make sure you do not mistype the password and then realize you do not know what it is after you have completed the installation. Choosing Target Architecture specifies which specific hardware architecture distribution is used during installation. click the Next button after you have approved the settings or change them before continuing the installation. To override this default and use text mode instead. You can perform a kickstart installation in interactive mode. check them in the Language Support list. . This means that the installation program uses all the options pre-configured in the kickstart file. select the Perform installation in text mode option. To continue to the next screen. choose the time zone to use for the system. when the file is saved. Do not type an already encrypted password and select to encrypt it. Because a kickstart file is a plain text file that can be easily read. but it allows you to preview the options in each screen before continuing to the next screen. Choosing Reboot system after installation reboots your system automatically after the installation is finished. To configure the system to use UTC. however. it is recommended that an encrypted password be used. the plain text password that you typed are encrypted and written to the kickstart file. select Encrypt root password. Enter the desired root password for the system in the Root Password text entry box. select Use UTC clock. the default can be changed with the Language Configuration Tool (system-config-language) after installation. To save the password as an encrypted password in the file. To install languages in addition to the one selected from the Default Language pulldown menu. Type the same password in the Confirm Password text box. Kickstart installations are performed in graphical mode by default.
For example. For the NFS directory. if the FTP server contains the directory /mirrors/redhat/i386/RedHat/. Kickstart Configurator 29 2. For example. If the FTP server requires a username and password. if the NFS server contains the directory /mirrors/redhat/i386/RedHat/. NFS — Choose this option to install or upgrade from an NFS shared directory. enter the name of the HTTP directory that contains the RedHat directory. Be sure to verify that the ISO images are intact before you start the installation. Choose the type of kickstart installation or upgrade screen from the following options: • • CD-ROM — Choose this option to install or upgrade from the Red Hat Enterprise Linux CDROMs. FTP — Choose this option to install or upgrade from an FTP server. Hard Drive — Choose this option to install or upgrade from a hard drive. To verify them. Installation Method Figure 2-2. enter the fully-qualified domain name or IP address. Hard drive installations require the use of ISO (or CD-ROM) images. enter /mirrors/redhat/i386/ for the FTP directory. specify them as well. enter a fully-qualified domain name or IP address. Enter • • • .Chapter 2. enter the name of the NFS directory that contains the RedHat directory of the installation tree. if the HTTP server contains the directory /mirrors/redhat/i386/RedHat/. For the FTP directory. HTTP — Choose this option to install or upgrade from an HTTP server. In the FTP server text field. In the text field for the the NFS server. enter the name of the FTP directory that contains the RedHat directory. use an md5sum program as well as the linux mediacheck boot option as discussed in the Red Hat Enterprise Linux Installation Guide.2. the Partition Information and Package Selection options are disabled. enter /mirrors/redhat/i386/ for the HTTP directory. For example. They are not supported for kickstart upgrades. If you choose upgrade. enter /mirrors/redhat/i386/ for the NFS directory. In the text field for the HTTP server. Installation Method The Installation Method screen allows you to choose whether to perform a new installation or an upgrade. enter a fully-qualified domain name or IP address. For the HTTP directory.
Select Use GRUB password. when the file is saved. Boot Loader Options GRUB is the default boot loader for Red Hat Enterprise Linux. Type the same password in the Confirm Password text field. unselect to encrypt it. if you have an IDE CD-ROM Writer.3. 2. /dev/hda1) in the Hard Drive Partition text box. the plain text password that you typed are encrypted and written to the kickstart file. You can password protect the GRUB boot loader by configuring a GRUB password. If you do not want to install a boot loader. To save the password as an encrypted password in the file. make sure you create a boot diskette or have another way to boot your system. . select Do not install a boot loader. You must choose where to install the boot loader (the Master Boot Record or the first sector of the /boot partition). Boot Loader Options Figure 2-3. while preserving the old entries. and enter a password in the Password field. Enter the directory that contains the ISO images in the Hard Drive Directory text box. select Encrypt GRUB password. select Upgrade existing boot loader to upgrade the existing boot loader configuration. enter them in the Kernel parameters text field. you can tell the kernel to use the SCSI emulation driver that must be loaded before using cdrecord by configuring hdd=ide-scsi as a kernel parameter (where hdd is the CD-ROM device). Kickstart Configurator the hard drive partition that contains the ISO images (for example. Install the boot loader on the MBR if you plan to use it as your boot loader. such as a third-party boot loader. If the encryption option is selected. To pass any special parameters to the kernel to be used when the system boots. If you choose not to install a boot loader. For example. If type an already encrypted password.30 Chapter 2. If Upgrade an existing installation is selected on the Installation Method page.
select Initialize the disk label if you are installing on a brand new hard drive. The Partition Options window shown in Figure 2-5 appears. msdos for x86 and gpt for Itanium). click the Add button. Create the partition on a specific hard drive. and partition size for the new partition. specify hda as the drive. remove all existing Linux partitions. 2. up to a chosen size. or preserve existing partitions. Format the partition as the chosen file system type. you can select to have the installation program create the swap partition with the recommended size instead of specifying a size. Creating Partitions To create a partition. or fill the remaining space on the hard drive. Use an existing partition. • • • • . Partition Information Select whether or not to clear the Master Boot Record (MBR). to make the partition on the first partition on the first IDE hard disk (/dev/hda1). file system type. to make the partition on the first IDE hard disk (/dev/hda). choose to make the partition a fixed size.1. Choose the mount point. Do not include /dev in the partition name. Choose to remove all existing partitions. Force the partition to be created as a primary partition. If you selected swap as the file system type.4. you can also choose from the following: • In the Additional Size Options section. specify hda1 as the partition. Kickstart Configurator 31 2. Optionally.4. Partition Information Figure 2-4.Chapter 2. For example. For example. Do not include /dev in the drive name. To initialize the disk label to the default for the architecture of the system (for example.
Click the RAID button. 2.4.32 Chapter 2. select the partition from the list and click the Edit button. you must specify a hard drive on which to make the partition or specify an existing partition to use. use the following steps: 1.1. Figure 2-6. The same Partition Options window appears as when you chose to add a partition as shown in Figure 2-5. Select Create a software RAID partition. 3. Creating a Software RAID Partition .1. 2. Also. except select Software RAID as the file system type. Kickstart Configurator Figure 2-5. Configure the partitions as previously described. To delete an existing partition. select the partition from the list and click the Delete button. except it reflects the values for the selected partition. Creating Partitions To edit an existing partition. Modify the partition options and click OK. Creating Software RAID Partitions To create a software RAID partition.
3. Select a mount point. Click the RAID button. RAID level. Kickstart Configurator 33 Repeat these steps to create as many partitions as needed for your RAID setup. and whether to format the RAID device. RAID members. RAID device name. Select Create a RAID device. follow these steps: 1. 2. Creating a Software RAID Device 4. . After creating all the partitions needed to form a RAID device. number of spares for the software RAID device. Figure 2-7. Click OK to add the device to the list. file system type. All of your partitions do not have to be RAID partitions.Chapter 2.
. eth1 for the second Ethernet card. Refer to Chapter 18 Network Configuration for details. click Add Network Device and select the network device and network type for the device. Networking can always be configured after installation with the Network Administration Tool (system-config-network). For each Ethernet card on the system. do not configure one on the Network Configuration page. or HTTP).34 Chapter 2. Networking is only required if you choose a networking-based installation method (NFS. Kickstart Configurator 2. Network Configuration Figure 2-8. FTP. Select eth0 to configure the first Ethernet card. Network Configuration If the system to be installed via kickstart does not have an Ethernet card. and so on.5.
click the checkbox next to Enable. click the appropriate tab. Firewall Configuration The Firewall Configuration window is similar to the screen in the installation program and the Security Level Configuration Tool. Authentication In the Authentication section. Kickstart Configurator 35 2. The Authentication Configuration options allow you to configure the following methods of authentication: • • • • • • NIS LDAP Kerberos 5 Hesiod SMB Name Switch Cache These methods are not enabled by default. To enable one or more of these methods.7. Refer to Chapter 27 Authentication Configuration for more information about the options. These options are highly recommended and chosen by default. . and enter the appropriate information for the authentication method. 2. select whether to use shadow passwords and MD5 encryption for user passwords.6.Chapter 2. Authentication Figure 2-9.
7. list any additional ports that should be opened for remote access. specify imap:tcp. If this option is not chosen. the X configuration options are disabled and the skipx option is written to the kickstart file. the system allows complete access to any active services and ports. such as DNS replies or DHCP requests. SELinux Configuration Although configuration for SELinux is not specified in the Kickstart Configurator. you can choose to allow specific services through the firewall. For example. you might want to allow connections from it. Only devices configured in the Network Configuration section are listed as available Trusted devices. No connections to the system are refused or denied. Use the following format: port:protocol. Selecting Enable firewall configures the system to reject incoming connections that are not in response to outbound requests. . Kickstart Configurator Figure 2-10. For example. if eth1 only receives connections from internal system. you can configure it during the kickstart installation by checking the Configure the X Window System option on the Display Configuration window as shown in Figure 2-11.1. 2. separate them with commas. Firewall Configuration If Disable firewall is selected. kickstart enables SELinux in enforcing mode by default if the selinux parameter is omitted from the kickstart file. To specify multiple ports. If a service is selected in the Trusted services list. Display Configuration If you are installing the X Window System.8.36 Chapter 2. to allow IMAP access through the firewall. enter 1234:udp. 2. to allow UDP packets on port 1234 through the firewall. Specify numeric ports can also be specified. Connections from any devices selected in the list are accepted by the system. If access to services running on this machine is required. connections for the service are accepted and processed by the system. In the Other ports text field.
If only one desktop is to be installed. Be sure to specify a color depth and resolution that is compatible with the video card and monitor for the system. you can select the video card from the list on the Video Card tab as shown in Figure 2-12. This option starts the system in runlevel 5 with the graphical login screen. root password. Also select whether to start the Setup Agent the first time the system is rebooted. After the system is installed. 2. If this option is selected and the installation program cannot successfully probe the video card. Alternatively.2. you must choose which desktop should be the default. be sure to choose it. security level.General If you are installing both the GNOME and KDE desktops. Select them from their respective pulldown menus. Once the system is installed. .8. Next. Kickstart Configurator 37 2. mouse. Probing works for most modern video cards. but the setting can be changed to enabled or enabled in reconfiguration mode.1. It is disabled by default. choose whether to start the X Window System when the system is booted. To continue the installation process. Video Card Probe for video card is selected by default. time zone. Accept this default to have the installation program probe for the video card during installation. X Configuration . Figure 2-11. the installation program stops at the video card configuration screen. Reconfiguration mode enables the language.8. this can be changed by modifying the /etc/inittab configuration file. select your video card from the list and click Next. Specify the amount of video RAM the selected video card has from the Video Card RAM pulldown menu. users can choose which desktop they want to be their default. General The first step in configuring X is to choose the default color depth and resolution. keyboard. These values are used by the installation program to configure the X Window System. and networking configuration options in addition to the default ones.Chapter 2.
8.Video Card 2. click on the Monitor tab as shown in Figure 2-13.3. Kickstart Configurator Figure 2-12. Figure 2-13. X Configuration . Monitor After configuring the video card. X Configuration .38 Chapter 2.Monitor .
9. Probing works for most modern monitors. If this option is selected and the installation program cannot successfully probe the monitor. There are also options available to resolve and ignore package dependencies automatically. the installation program stops at the monitor configuration screen.Chapter 2. Refer to Section 1. Accept this default to have the installation program probe for the monitor during installation. To continue the installation process. Alternatively. 2. Package Selection Figure 2-14. Currently. This option is useful if the monitor for the system is not listed. Kickstart Configurator does not allow you to select individual packages. Package Selection The Package Selection window allows you to choose which package groups to install. Kickstart Configurator 39 Probe for monitor is selected by default. To install individual packages.5 Package Selection for details. select your monitor from the list and click Next. you can select your monitor from the list. modify the %packages section of the kickstart file after you save it. Notice that when this option is enabled. the monitor list is disabled. . You can also specify the horizontal and vertical sync rates instead of selecting a specific monitor by checking the Specify hysnc and vsync instead of monitor option.
Pre-Installation Script You can add commands to run on the system immediately after the kickstart file has been parsed and before the installation begins. . For example. Kickstart Configurator 2. If you have configured the network in the kickstart file.2 in your kickstart file. type it in the text area.10. select the Use an interpreter option and enter the interpreter in the text box beside it. the network is enabled before this section is processed. To include a pre-installation script. To specify a scripting language to use to execute the script. /usr/bin/python2.40 Chapter 2. Pre-Installation Script Figure 2-15. Caution Do not include the %pre command. This option corresponds to using %pre --interpreter /usr/bin/python2.2 can be specified for a Python script. It is added for you.
Kickstart Configurator 41 2.1 Examples.7. type it in the text area. add the following command to the %post section: echo "Hackers will be punished!" > /etc/motd Tip More examples can be found in Section 1. to change the message of the day for the newly installed system. Post-Installation Script Figure 2-16. the network is enabled.Chapter 2. To include a post-installation script.11. Caution Do not include the %post command. and the script can include commands to access resources on the network. Post-Installation Script You can also add commands to execute on the system after the installation is completed. For example. If the network is properly configured in the kickstart file. . It is added for you.
Select where to save the file. the previous example must be changed to the following: echo "Hackers will be punished!" > /mnt/sysimage/etc/motd 2. /usr/bin/python2.2 can be specified for a Python script. you must prepend the directory name with /mnt/sysimage/. Saving the File To review the contents of the kickstart file after you have finished choosing your kickstart options.1. To make changes to the newly installed file system.42 Chapter 2. click the checkbox next to this option on the top of the Post-Installation window.11.11. select File => Save File or press [Ctrl]-[S]. This option corresponds to using %post --interpreter /usr/bin/python2. After saving the file. . refer to Section 1. For example. select the Use an interpreter option and enter the interpreter in the text box beside it. Kickstart Configurator 2. To save the file without previewing it. Chroot Environment To run the post-installation script outside of the chroot environment. 2.2. within the post-installation section. Figure 2-17. if you select Run outside of the chroot environment.10 Starting a Kickstart Installation for information on how to start the kickstart installation. A dialog box appears. Use an Interpreter To specify a scripting language to use to execute the script. but outside of the chroot environment. This is equivalent to using the --nochroot option in the %post section. click the Save to File button in the preview window.12.2 in your kickstart file. Preview To save the kickstart file. select File => Preview from the pull-down menu. For example.
2. 3. The following steps must be performed to prepare for a PXE installation: 1. type the command system-config-netboot at a shell prompt (for example. Start the tftp service. A separate PXE server is not necessary. a bootable flash memory drive. or by using the askmethod boot option with the Red Hat Enterprise Linux CD #1. you must be running the X Window System. A network installation can be started from a boot CD-ROM.Chapter 3. Configure DHCP. HTTP) server to export the installation tree. Setting up the Network Server First. Configure which hosts are allowed to boot from the PXE configuration. and start the installation. 3. other network information such as name server. or HTTP server to export the entire installation tree for the version and variant of Red Hat Enterprise Linux to be installed. refer to To use the graphical version of the Network Booting Tool. 3. 4. of these instructions. 6. . Boot the client. FTP. Alternatively. PXE Boot Configuration The next step is to copy the files necessary to start the installation to the tftp server so they can be found when the client requests them. The tftp server is usually the same server as the network server exporting the installation tree. For the command line version Section 3. it can be configured to boot from files on another networked system rather than local media such as a CD-ROM. FTP. which is part of the syslinux package. if the system to be installed contains a network interface card (NIC) with Pre-Execution Environment (PXE) support. Configure the files on the tftp server necessary for PXE booting. configure an NFS. in an XTerm or a GNOME terminal).2. FTP. To copy these files. FTP.1. run the Network Booting Tool on the NFS. Refer to the section Preparing for a Network Installation in the Red Hat Enterprise Linux Installation Guide for detailed instructions. or HTTP protocols. This is possible because of PXELINUX. the client's NIC with PXE support sends out a broadcast request for DHCP information. 5. 2. The DHCP server provides the client with an IP address. the IP address or hostname of the tftp server (which provides the files necessary to start the installation program). Configure the network (NFS. go to Applications (the main menu on the panel) => System Settings => Server Settings => Network Booting Service. have root privileges. For a PXE network installation.1 Command Line Configuration. and have the system-config-netboot RPM package installed. PXE Network Installations Red Hat Enterprise Linux allows for installation over a network using the NFS. and the location of the files on the tftp server. To start the Network Booting Tool from the desktop. Or. or HTTP server.
Description — Provide a brief description of the Red Hat Enterprise Linux version and variant.44 Chapter 3. If FTP or HTTP was selected. the pxeos command line utility.com \ -L <net-location> -k <kernel> -K <kickstart> <os-identifer> . select Configure => Network Installation from the pulldown menu. the directory must be relative to the default directory for the FTP server or the document root for the HTTP server. FTP.example. Otherwise. can be used to configure the tftp server files as described in Section 3. The file can be a URL or a file stored locally (diskette). It is used as the directory name in the /tftpboot/linux-install/ directory. Location — Provide the directory shared by the network server. uncheck Anonymous FTP and provide a valid username and password combination. The kickstart file can be created with the Kickstart Configurator. The dialog in Figure 3-1 is displayed. FTP. Figure 3-1. PXE Network Installations If starting the Network Booting Tool for the first time. If FTP is selected and anonymous FTP is not being used. Command Line Configuration If the network server is not running X.img and vmlinuz files necessary to boot the installation program are transfered from images/pxeboot/ in the provided installation tree to /tftpboot/linux-install/<os-identifier>/ on the tftp server (the one you are running the Network Booting Tool on). Server — Provide the IP address or domain name of the NFS.4 Starting the tftp Server: pxeos -a -i "<description>" -p <NFS|HTTP|FTP> -D 0 -s client. which is part of the system-config-netboot package. For all network installations. Refer to Chapter 2 Kickstart Configurator for details. and then click Add.2.1. 3. select Network Install from the First Time Druid. Selects protocol for installation — Selects NFS. Network Installation Setup • Operating system identifier — Provide a unique name using one word to identify the Red Hat Enterprise Linux version and variant. the directory provided must contain the RedHat/ directory of the installation tree. the initrd. or HTTP as the network installation type depending on which one was configured previously. or HTTP server. • • • • • After clicking OK. Kickstart — Specify the location of the kickstart file.
example. <NFS|HTTP|FTP> — Specify which of the NFS.3. FTP. or HTTP server after the -s option. • -D • -s • -L • -k • -K • <net-location> — Provide the location of the installation tree on that server after the -L option. This corresponds to the Select protocol for installation menu in Figure 3-1. refer to the pxeos man page. Only one may be specified. Add Hosts . if available. Figure 3-2.com — Provide the name of the NFS. This corresponds to the Location field in Figure 3-1. PXE Network Installations The following list explains the options: • -a 45 — Specifies that an OS instance is being added to the PXE configuration. specify a username and password for login. field in Figure 3-1. <kickstart> — Provide the location of the kickstart file. 3. FTP. • -i "<description>" — Replace • -p "<description>" with a description of the OS instance. This corresponds to the Description field in Figure 3-1. This corresponds to the Server field in Figure 3-1. with the following options before <os-identifer> in the previous command: -A 0 -u <username> -p <password> For more information on command line options available for the pxeos command. <kernel> — Provide the specific kernel version of the server installation tree for booting. the interface as shown in Figure 3-2 is displayed. which is used as the directory name in the If FTP is selected as the installation protocol and anonymous login is not available. or HTTP protocols to use for installation. This corresponds to the Operating system identifier <os-identifer> — Specify the OS identifier. <0|1> — Specify "0" which indicates that it is not a diskless configuration since pxeos can be used to configure a diskless environment as well.Chapter 3. /tftpboot/linux-install/ directory. client. Adding PXE Hosts After configuring the network server.
the pxeboot utility. <os-identifier> — Specifies the operating system identifier as defined in Section 3. refer to the pxeboot man page.1 Command Line Configuration. . PXE Network Installations The next step is to configure which hosts are allowed to connect to the PXE boot server. a part of the system-config-netboot package. <value> — Specifies the ram disk size.cfg. <kickstart> — The location of the kickstart file. They are only used for diskless environments. This file can be created with the Kickstart Configurator. Command Line Configuration If the network server is not running X.46 Chapter 3. such as http://server. For the command line version of this step.com/kickstart/ks. Kickstart File — The location of a kickstart file to use. Figure 3-3.1. Operating System — The operating system identifier to install on this client. The list is populated from the network install instances created from the Network Installation Dialog. can be used to add hosts which are allowed to connect to the PXE server: pxeboot -a -K <kickstart> -O <os-identifier> -r <value> <host> The following list explains the options: • -a • -K • -O • -r • — Specifies that a host is to be added. 3. Add a Host Enter the following information: • • • • Hostname or IP Address/Subnet — The IP address. Refer to Chapter 2 Kickstart Configurator for details. refer to Section 3.2 PXE Boot Configuration. For more information on command line options available for the pxeboot command. To add hosts. or a subnet of systems that should be allowed to connect to the PXE server for installations. Ignore the Snapshot name and Ethernet options. Serial Console — This option allows use of a serial console. <host> — Specifies the IP address or hostname of the host to add. fully qualified hostname. refer to Chapter 4 Diskless Environments for details. For more information on configuring a diskless environment. click the New button. if available.3.3.example.
Refer to Chapter 24 Dynamic Host Configuration Protocol (DHCP) for details.5. 9) = "PXEClient". Configuring the DHCP Server If a DHCP server does not already exist on the network. filename "linux-install/pxelinux. .6. modify /tftpboot/linux-install/msgs/boot. allow bootp. 3. class "pxeclients" { match if substring(option vendor-class-identifier. 4. After the system boots the installation program. If it is not installed. next-server <server-ip>. refer to Part III Package Management. 0. Performing the PXE Installation For instructions on how to configure the network interface card with PXE support to boot from the network. consult the documentation for the NIC. install it via Red Hat Network or the Red Hat Enterprise Linux These commands configure the tftp and xinetd services to immediately turn on and also configure them to start at boot time in runlevels 3. 3.msg to use a custom boot message.Chapter 3. PXE Network Installations 47 3. Make sure the configuration file contains the following so that PXE booting is enabled for systems which support it: allow booting. Starting the tftp Server CD-ROMs.4. Adding a Custom Boot Message Optionally. and 5. For more information on installing RPM packages. } where <next-server> option should be replaced with the IP address of the tftp server.0". configure one.7. tftp is an xinetd-based service. 3. verify that the tftp-server package is installed with the command rpm -q tftp-server. refer to the Red Hat Enterprise Linux Installation Guide. start it with the following commands: /sbin/chkconfig --level 345 xinetd on /sbin/chkconfig --level 345 tftp on On the DHCP server. It varies slightly per card.
PXE Network Installations .48 Chapter 3.
Each client has its own read-write directory so that one client can not affect the others. Copy Red Hat Enterprise Linux from the client system to the server using rsync. Configure each diskless client to boot via PXE and boot them. and 5. Diskless Environments Some networks require multiple systems with the same configuration. Start the tftp Server CD-ROMs. start it with the following commands: /sbin/chkconfig --level 345 xinetd on /sbin/chkconfig --level 345 tftp on On the DHCP server. 4.4 Finish Configuring the Diskless Environment. One solution is to use a diskless environment in which most of the operating system. They also require that these systems be easy to reboot. and manage. 6. Finish creating the diskless environment Section 4.1 Start the tftp Server. is shared from a central server between the clients. install it via Red Hat Network or the Red Hat Enterprise Linux These commands configure the tftp and xinetd services to immediately turn on and also configure them to start at boot time in runlevels 3. 9. which can be read-only. Depending on these factors. Install Red Hat Enterprise Linux on a system so that the files can be copied to the NFS server. The individual clients have their own directories on the central server for the rest of the operating system. Each time the client boots. Configure the DHCP server as discussed in Section 4.2 Configuring the DHCP Server. For example: rsync -a -e ssh installed-system. . upgrade. this operation may take a while. If it is not installed. For example: mkdir -p /diskless/i386/RHEL4-AS/ This directory is referred to as the diskless directory. tftp is an xinetd-based service. 5. refer to Part III Package Management. 4. which must be read/write.com:/ /diskless/i386/RHEL4-AS/root/ The length of this operation depends on the network connection speed as well as the size of the file system on the installed system. For more information on installing RPM packages. 7. as discussed in 8.example. it mounts most of the OS from the NFS server as read-only and another directory as read-write. Configure the diskless clients as discussed in Section 4. (Refer to the Red Hat Enterprise Linux Installation Guide for details. 3.5 Adding Hosts. The following steps are necessary to configure Red Hat Enterprise Linux to run on a diskless client: 1. verify that the tftp-server package is installed with the command rpm -q tftp-server. Create a directory on the NFS server to contain the diskless environment such as /diskless/i386/RHEL4-AS/. 2.) Any software to be used on the clients must be installed on this system and the busybox-anaconda package must be installed. Create a subdirectory of this directory named root/: mkdir -p /diskless/i386/RHEL4-AS/root/ 4.Chapter 4.1. Start the tftp server as discussed in Section 4.
have root privileges. Click Forward. class "pxeclients" { match if substring(option vendor-class-identifier. Enter the IP address or domain name of the NFS server configured in Section 4. Configure NFS to export the root/ and snapshot/ directories by adding them to /etc/exports. 2.sync. On the Diskless Identifier page. select Diskless from the First Time Druid. Click Forward. select Configure => Diskless from the pull-down menu. reload the configuration file: service nfs reload 4. Configuring the NFS Server The shared read-only part of the operating system is shared via NFS.3 Configuring the NFS Server as well as the directory exported as the diskless environment. you must be running the X Window System. Make the hostname declaration as specific as possible.no_root_squash) Replace * with one of the hostname formats discussed in Section 22. go to Applications (the main menu on the panel) => System Settings => Server Settings => Network Booting Service. type the command system-config-netboot at a shell prompt (for example. For example: /diskless/i386/RHEL4-AS/root/ *(ro.3. and have the system-config-netboot RPM package installed. Refer to Chapter 24 Dynamic Host Configuration Protocol (DHCP) for details. enter a Name and Description for the diskless environment.2 Hostname Formats. A wizard appears to step you through the process: 1. .sync. Otherwise.50 Chapter 4. so unwanted systems can not access the NFS mount. If the NFS service is not running. To start the Network Booting Tool from the desktop. filename "linux-install/pxelinux. If starting the Network Booting Tool for the first time. Make sure the configuration file contains the following so that PXE booting is enabled for systems which support it: allow booting. configure one. } where <next-server> option should be replaced with the IP address of the tftp server. Configuring the DHCP Server If a DHCP server does not already exist on the network.4. 4. 0. and then click Add. next-server <server-ip>.2. Diskless Environments 4. Or.no_root_squash) /diskless/i386/RHEL4-AS/snapshot/ *(rw.0". 9) = "PXEClient". Click Forward on the first page. 3. allow bootp. Finish Configuring the Diskless Environment To use the graphical version of the Network Booting Tool. in an XTerm or a GNOME terminal).3. start it: service nfs start If the NFS service is already running.
custom files using the mount -o bind over the read-only .custom file in the same directory as the files file. create a files. Add Diskless Host In the existing snapshot/ directory in the diskless directory. Then it mounts all the files and directories in the files and files. Ignore the Kickstart File option. a window appears to allow hosts to be added for the diskless environment. 5. After clicking Apply. If additional entries must be added to the list. Diskless Environments 51 4.Chapter 4. Enter a subnet to specify a group of systems. It also mounts its individual snapshot directory as read/write. Then. Do not modify this file. a subdirectory is created with the Snapshot name specified as the file name. Figure 4-1. it mounts the remote root/ directory in the diskless directory as read-only. provide the following information: • • • • • Hostname or IP Address/Subnet — Specify the hostname or IP address of a system to add it as a host for the diskless environment. select eth0. When the diskless client boots. 4. Click the New button. In the dialog shown in Figure 4-1.custom are copied copy from the root/ directory to this new directory. They are copied to the PXE boot directory /tftpboot/linux-install/<os-identifier>/. /diskless/i386/RHEL4-AS/snapshot/) with a file called files in it. Ethernet — Select the Ethernet device on the host to use to mount the diskless environment. After completing the steps in Section 4. The Network Booting Tool can be used to create these snapshot directories. If the host only has one Ethernet card. Select the kernel version to boot on the diskless system. It is only used for PXE installations. This file contains a list of files and directories that must be read/write for each diskless system.6. all of the files listed in snapshot/files and snapshot/files. The kernel versions installed in the diskless environment are listed. Click Apply to finish the configuration. the diskless kernel and image file are created based on the kernel selected. and add each additional file or directory on a separate line. Operating System — Select the diskless environment for the host or subnet of hosts.5. Booting the Hosts Consult the documentation for your PXE card to configure the host to boot via PXE. Adding Hosts Each diskless client must have its own snapshot directory on the NFS server that is used as its read/write file system.4 Finish Configuring the Diskless Environment. Snapshot name — Provide a subdirectory name to be used to store all of the read/write content for the host. The directory snapshot/ is created in the same directory as the root/ directory (for example. 4. Serial Console — Select this checkbox to perform a serial installation.
52 Chapter 4. . Diskless Environments diskless directory to allow applications to write to the root directory of the diskless environment if they need to.
refer to Section 5.Chapter 5.1. 5. Another common problem occurs when using a partitioning tool to resize a partition or create a new partition from free space after installation. you might not be able to reboot into Red Hat Enterprise Linux. For instructions on how to reinstall the GRUB boot loader from a rescue environment. You forgot the root password.1 Reinstalling the Boot Loader. boot in rescue mode and modify the /boot/grub/grub. Root Password What can you do if you forget your root password? To reset it to a different password. if you boot into one of the system recovery modes. you cannot boot Red Hat Enterprise Linux unless you can get into rescue mode and reconfigure the boot loader. Basic System Recovery When things go wrong. However. these methods require that you understand the system well. 5. where you can use your own knowledge to repair the system. 5.2. Common Problems You might need to boot into one of these recovery modes for any of the following reasons: • • • You are unable to boot normally into Red Hat Enterprise Linux (runlevel 3 or 5). If the boot loader is overwritten in this manner. . If either of these occur. and emergency mode. To fix this problem. and use the passwd command to reset the root password. You are having hardware or software problems.conf file. the boot loader might not be able to find it to mount the partition.1.1. If the partition number of your / partition changes. 5. there are ways to fix problems. Hardware/Software Problems This category includes a wide variety of different situations. boot into rescue mode or single-user mode. This chapter describes how to boot into rescue mode.2.1.3. Unable to Boot into Red Hat Enterprise Linux This problem is often caused by the installation of another operating system after you have installed Red Hat Enterprise Linux. single-user mode. However. you might be able to resolve the problem or at least get copies of your most important files. Some other operating systems assume that you have no other operating system(s) on your computer. They overwrite the Master Boot Record (MBR) that originally contained the GRUB boot loader. and it changes the order of your partitions. and you want to get a few important files off of your system's hard drive.1. Two examples include failing hard drives and specifying an invalid root device or kernel in the boot loader configuration file.
Choose Skip if you think your file system is corrupted. for an x86 system. it attempts to mount your file system under the directory /mnt/sysimage/. During normal operation. add the keyword rescue as a kernel parameter. store your files. you can access the files stored on your system's hard drive. Booting into Rescue Mode Rescue mode provides the ability to boot a small Red Hat Enterprise Linux environment entirely from CD-ROM. If you select Read-Only. However. 1. or HTTP server. If you want to proceed with this step choose 'Continue'. If you select a rescue image that does not require a network connection.2. Using rescue mode. FTP server. If you select Continue. Once you have booted using one of the described methods. NFS image. instead of the system's hard drive. your Red Hat Enterprise Linux system uses files located on your system's hard drive to do everything — run programs. If it fails to mount a partition. and the installation tree must be for the same version of Red Hat Enterprise Linux as the Red Hat Enterprise Linux CDROM #1 from which you booted. it attempts to mount your file system under the directory /mnt/sysimage/. Refer to the Red Hat Enterprise Linux Installation Guide for more details. you must be able to boot the system using one of the following methods 1: • • • By booting the system from an installation boot CD-ROM. For example. The location selected must contain a valid installation tree. type the following command at the installation boot prompt: linux rescue You are prompted to answer a few basic questions. You can then make any changes required to your system. for example. To boot into rescue mode. A network connection is useful if you need to backup files to a different computer or install some RPM packages from a shared network location. or HTTP.54 Chapter 5. including which language to use. Hard Drive. there may be times when you are unable to get Red Hat Enterprise Linux running completely enough to access files on your system's hard drive. It also prompts you to select where a valid rescue image is located. As the name implies. By booting the system from other installation boot media. or some other boot method. If you used a boot CD-ROM or other media to start rescue mode. For more information about how to setup an installation tree on a hard drive. Select from Local CD-ROM. FTP. your file system is not mounted. it notifies you. you are asked whether or not you want to establish a network connection. NFS server. If you select Skip. the installation tree must be from the same tree from which the media was created. rescue mode is provided to rescue you from something. refer to the Red Hat Enterprise Linux Installation Guide. Basic System Recovery 5. but in read-only mode. such as USB flash devices. You can also choose to mount your file systems read-only instead of read-write by choosing 'Read-only'. If for some reason this process fails you can choose 'Skip' and this step will be skipped and you will go directly to a command shell. even if you cannot actually run Red Hat Enterprise Linux from that hard drive. . By booting the system from the Red Hat Enterprise Linux CD-ROM #1. The following message is displayed: The rescue environment will now attempt to find your Linux installation and mount it under the directory /mnt/sysimage. and more.
/foo is a directory that you have created and /dev/mapper/VolGroup00-LogVol02 is the LVM2 logical volume you want to mount.Chapter 5. volume groups. Basic System Recovery 55 Once you have your system in rescue mode. use the following command to list them: fdisk -l If you do not know the names of all LVM2 physical volumes. type exit to return to the prompt. you can run many useful commands. scp. the default root partition while in rescue mode is a temporary root partition. and typing the following command: mount -t ext3 /dev/mapper/VolGroup00-LogVol02 /foo In the above command. a prompt appears on VC (virtual console) 1 and VC 2 (use the [Ctrl]-[Alt]-[F1] key combination to access VC 1 and [Ctrl]-[Alt]-[F2] to access VC 2): sh-3. Even if your file system is mounted. To exit the chroot environment.00b# If you selected Continue to mount your partitions automatically and they were mounted successfully. If the partition is of type ext2. or logical volumes. use the following commands to list them: pvdisplay vgdisplay lvdisplay From the prompt. • dump and ping if the network is started and restore for users with tape drives and fdisk for managing partitions • parted • rpm • joe for installing or upgrading software for editing configuration files Note If you try to start other popular editors such as emacs. . you can change the root partition of the rescue mode environment to the root partition of your file system by executing the following command: chroot /mnt/sysimage This is useful if you need to run commands such as rpm that require your root partition to be mounted as /. you are in single-user mode. the joe editor is started. or vi. replace ext3 with ext2. such as: • ssh. you can still try to mount a partition or LVM2 logical volume manually inside rescue mode by creating a directory such as /foo. pico. not the root partition of the file system used during normal user mode (runlevel 3 or 5). If you do not know the names of all physical partitions. If you selected Skip. If you selected to mount your file system and it mounted successfully.
Chapter 5. Basic System Recovery
5.2.1. Reinstalling the Boot Loader
In many cases, the GRUB boot loader can mistakenly be deleted, corrupted, or replaced by other operating systems. The following steps detail the process on how GRUB is reinstalled on the master boot record:
• • • • • •
Boot the system from an installation boot medium. Type linux rescue at the installation boot prompt to enter the rescue environment. Type chroot /mnt/sysimage to mount the root partition. Type /sbin/grub-install /dev/hda to reinstall the GRUB boot loader, where /dev/hda is the boot partition. Review the /boot/grub/grub.conf file, as additional entries may be needed for GRUB to control additional operating systems. Reboot the system.
5.3. Booting into Single-User Mode
One of the advantages of single-user mode is that you do not need a boot CD-ROM; however, it does not give you the option to mount the file systems as read-only or not mount them at all. If your system boots, but does not allow you to log in when it has completed booting, try single-user mode. In single-user mode, your computer boots to runlevel 1. Your local file systems are mounted, but your network is not activated. You have a usable system maintenance shell. Unlike rescue mode, single-user mode automatically tries to mount your file system. Do not use single-user mode if your file system cannot be mounted successfully. You cannot use single-user mode if the runlevel 1 configuration on your system is corrupted. On an x86 system using GRUB, use the following steps to boot into single-user mode: 1. At the GRUB splash screen at boot time, press any key to enter the GRUB interactive menu. 2. Select Red Hat Enterprise Linux with the version of the kernel that you wish to boot and type a to append the line. 3. Go to the end of the line and type single as a separate word (press the [Spacebar] and then type single). Press [Enter] to exit edit mode.
5.4. Booting into Emergency Mode
In emergency mode, you are booted into the most minimal environment possible. The root file system is mounted read-only and almost nothing is set up. The main advantage of emergency mode over single-user mode is that the init files are not loaded. If init is corrupted or not working, you can still mount file systems to recover data that could be lost during a re-installation. To boot into emergency mode, use the same method as described for single-user mode in Section 5.3 Booting into Single-User Mode with one exception, replace the keyword single with the keyword emergency.
II. File Systems
File system refers to the files and directories stored on a computer. A file system can have different formats called file system types. These formats determine how the information is stored as files and directories. Some file system types store redundant copies of the data, while some file system types make hard drive access faster. This part discusses the ext3 file system types.
Table of Contents
6. The ext3 File System ..................................................................................................................... 59 7. Logical Volume Manager (LVM)................................................................................................. 63 8. LVM Configuration....................................................................................................................... 65 9. Redundant Array of Independent Disks (RAID) ....................................................................... 73 10. Software RAID Configuration ................................................................................................... 77 11. Swap Space .................................................................................................................................. 85 12. Managing Disk Storage .............................................................................................................. 89 13. Implementing Disk Quotas ........................................................................................................ 97 14. Access Control Lists.................................................................................................................. 103
Chapter 6.
The ext3 File System
The default file system is the journaling ext3 file system.
6.1. Features of ext3
The ext3 file system is essentially an enhanced version of the ext2 file system. These improvements provide the following advantages: Availability After an unexpected power failure or system crash (also called an unclean system shutdown), each mounted ext2 file system on the machine must be checked for consistency by the e2fsck program. This is a time-consuming process that can delay system boot time significantly, especially with large volumes containing a large number of files. During this time, any data on the volumes is unreachable. The journaling provided by the ext3 file system means that this sort of file system check is no longer necessary after an unclean system shutdown. The only time a consistency check occurs using ext3 is in certain rare hardware failure cases, such as hard drive failures. The time to recover an ext3 file system after an unclean system shutdown does not depend on the size of the file system or the number of files; rather, it depends on the size of the journal used to maintain consistency. The default journal size takes about a second to recover, depending on the speed of the hardware. Data Integrity The ext3 file system provides stronger data integrity in the event that an unclean system shutdown occurs. The ext3 file system allows you to choose the type and level of protection that your data receives. By default, the ext3 volumes are configured to keep a high level of data consistency with regard to the state of the file system. Speed Despite writing some data more than once, ext3 has a higher throughput in most cases than ext2 because ext3's journaling optimizes hard drive head motion. You can choose from three journaling modes to optimize speed, but doing so means trade-offs in regards to data integrity. Easy Transition It is easy to migrate from ext2 to ext3 and gain the benefits of a robust journaling file system without reformatting. Refer to Section 6.3 Converting to an ext3 File System for more on how to perform this task. The following sections walk you through the steps for creating and tuning ext3 partitions. For ext2 partitions, skip the partitioning and formating sections below and go directly to Section 6.3 Converting to an ext3 File System.
6.2. Creating an ext3 File System
After installation, it is sometimes necessary to create a new ext3 file system. For example, if you add a new disk drive to the system, you may want to partition the drive and use the ext3 file system.
60 The steps for creating an ext3 file system are as follows: 1. Create the partition using parted or fdisk. 2. Format the partition with the ext3 file system using mkfs. 3. Label the partition using e2label. 4. Create the mount point. 5. Add the partition to the /etc/fstab file.
Chapter 6. The ext3 File System
6.3. Converting to an ext3 File System
The tune2fs program can add a journal to an existing ext2 file system without altering the data already on the partition. If the file system is already mounted while it is being transitioned, the journal is visible as the file .journal in the root directory of the file system. If the file system is not mounted, the journal is hidden and does not appear in the file system at all.
Note A default installation of Red Hat Enterprise Linux uses ext3 for all file systems.
To convert an ext2 file system to ext3, log in as root and type,
/sbin/tune2fs -j <file_system>
where <file_system> is an appropriate LVM2 file system. A valid LVM2 file system could be one of two types of entries:
• •
A static device — A traditional storage volume, for example, /dev/hdbX , where hdb is a storage device name and X is the partition number.
Issue the df command to display mounted file systems. For the remainder of this section, the sample commands use the following value:
After doing this, be certain to change the partition type from ext2 to ext3 in the /etc/fstab file. If you are transitioning your root file system, you must use an initrd image (or RAM disk) to boot. To create this, run the mkinitrd program. For information on using the mkinitrd command, type man mkinitrd. Also, make sure your GRUB configuration loads the initrd. If you fail to make this change, the system still boots, but the file system is mounted as ext2 instead of ext3.
Chapter 6. The ext3 File System
6.4. Reverting to an ext2 File System
Because ext3 is relatively new, some disk utilities do not yet support it. For example, you may need to shrink a partition with resize2fs, which does not yet support ext3. In this situation, it may be necessary to temporarily revert a file system to ext2. To revert a partition, you must first unmount the partition by logging in as root and typing,
umount /dev/mapper/VolGroup00-LogVol02
Next, change the file system type to ext2 by typing the following command as root:
/sbin/tune2fs -O ^has_journal /dev/mapper/VolGroup00-LogVol02
Check the partition for errors by typing the following command as root:
/sbin/e2fsck -y /dev/mapper/VolGroup00-LogVol02
Then mount the partition again as ext2 file system by typing:
mount -t ext2 /dev/mapper/VolGroup00-LogVol02 /mount/point
In the above command, replace /mount/point with the mount point of the partition. Next, remove the .journal file at the root level of the partition by changing to the directory where it is mounted and typing:
rm -f .journal
You now have an ext2 partition. If you want to permanently change the partition to ext2, remember to update the /etc/fstab file.
Chapter 6. The ext3 File System
1 GB Physical Volume 9.1 GB Physical Volume 9. A physical volume cannot span over more than one drive. Physical Volume 9. and partitions that are logical volumes can be expanded. Logical Volume Group /home and /m and file system types. Since a physical volume cannot span over multiple drives. The /boot/ partition cannot be on a logical volume group because the boot loader cannot read it. With LVM. to span over more than one drive.1 GB /boot 75 MB (ext3) Logical Volume Group (9.75 MB Figure 7-1. If the root (/) partition is on a logical volume. When "partitions" reach their full capacity. with the exception of the /boot/ partition. create one or more physical volumes per drive. a hard drive or set of hard drives is allocated to one or more physical volumes. When a new hard drive is added to the system. The physical volumes are combined into logical volume groups.Chapter 7. such as ext2 or ext3. What is LVM? LVM is a method of allocating hard drive space into logical volumes that can be easily resized instead of partitions.1. create a separate /boot/ partition which is not a part of a volume group.1 GB x 3) . . which are assigned mount points. Logical Volume Manager (LVM) 7. it can be added to the logical volume group. The logical volume group is divided into logical volumes. such as free space from the logical volume group can be added to the logical volume to increase the size of the partition.
7. LVM2. What is LVM2? LVM version 2.64 Chapter 7. Even if the partition is moved to another hard drive. Logical Volume Manager (LVM) Logical Volume Group (9. it is not easy to expand the size of the partition. Useful Websites • • http://sourceware.1. can be upgraded from versions of Red Hat Enterprise Linux running the 2. refer to Section 7. To learn how to configure LVM during the installation process. the original hard drive space has to be reallocated as a different partition or not used. and the default Red Hat kernel is compiled with LVM support. or LVM2. Installed Documentation • rpm -qd lvm • lvm help — This command shows all the documentation available from the lvm package.3. Logical Volumes On the other hand. which uses the device mapper driver contained in the 2. If a partition becomes full. http://tldp. including man pages.3 Additional Resources for further details on more complex requirements and upgrading scenarios.org/HOWTO/LVM-HOWTO/ — LVM HOWTO from the Linux Documentation Project. — This command shows all LVM commands available. which contains an overview. is the default for Red Hat Enterprise Linux. 7. refer to Chapter 8 LVM Configuration. the hard drive is divided into partitions of defined sizes. 7. 7. .75 MB Logical Volume /home 20 GB Logical Volume / 2 GB Free Space 5 GB Figure 7-2. LVM support must be compiled into the kernel.org/lvm2 — LVM2 webpage.2.6 kernel.3.4 kernel.1 GB x 3) . Additional Resources Use these sources to learn more about LVM. which is almost completely compatible with the earlier LVM1 version. and more.2. if a system is partitioned with the ext3 file system.3. link to the mailing lists. Although upgrading from LVM1 to LVM2 is usually seamless.
You can use the utilities from the lvm package to create your own LVM configuration post-installation. Note Although the following steps are illustrated during a GUI installation. select Automatically partition. the text-based installation process. 8.1 GB SCSI drives (/dev/sda and /dev/sdb) are used in the following examples. An overview of the steps required to configure LVM include: • • • Creating physical volumes from the hard drives. The following properties make up the automatically created configuration: • The /boot/ partition resides on its own non-LVM partition. Two LVM logical volumes (LogVol00 and LogVol01) are created from the newly created spanned volume group. A single LVM volume group (VolGroup00) is created. They detail how to create a simple configuration using a single LVM volume group with associated logical volumes during installation. Read Chapter 7 Logical Volume Manager (LVM) first to learn about LVM. Automatic Partitioning On the Disk Partitioning Setup screen. manual disk partitioning through Disk Druid is required.1. In the following example. or if you require RAID partitioning. or during a kickstart installation. and the remainder is allocated to the root file system. • • . the remainder of the first drive ( /dev/sda2). In the following example. In the following example. LVM is the default method for disk partitioning. Creating logical volumes from the volume groups and assign the logical volumes mount points. the same can be done during a text-based installation. If you do not wish to have LVM implemented. LVM Configuration LVM can be configured during the graphical installation process. Bootable partitions cannot reside on LVM logical volumes. and the entire second drive (/dev/sdb1) are allocated to the volume group. which spans all selected drives and all remaining space available. Creating volume groups from the physical volumes.Chapter 8. LogVol00. but these instructions focus on using Disk Druid during installation to complete this task. the recommended swap space is automatically calculated and assigned to LogVol01. For Red Hat Enterprise Linux. it is the first partition on the first drive (/dev/sda1). Two 9.
LVM Configuration Figure 8-1. Because there are numerous ways to manually configure a system with LVM. the default automatic LVM partitioning is sufficient.1 Automatic Partitioning. In most cases. the following example is similar to the default configuration done in Section 8. select Manually partition with Disk Druid. but advanced implementations could warrant modification or manual configuration of the LVM partition tables. On the Disk Partitioning Setup screen. Note If you anticipate future memory upgrades. Automatic LVM Configuration With Two SCSI Drives Note If enabling quotas are of interest to you. in which case. the automatic LVM configuration should be modified to leave available space for future growth. leaving some free space in the volume group would allow for easy future expansion of the swap space logical volume on the system. so that each file system has its own independent quota configuration limits.66 Chapter 8. Manual LVM Partitioning The following section explains how to manually configure LVM for Red Hat Enterprise Linux. it may be best to modify the automatic configuration to include other mount points. such as /home/ or /var/. . 8.2.
7. 2. If unselected. unselecting this option should be considered. 3. Select Force to be a primary partition to make the partition be a primary partition. 5. Select only the sda checkbox from the Allowable Drives area. the disk drives are new. 6.1. 4. Select ext3 from the File System Type pulldown menu. The following figure. Select New. A primary partition is one of the first four partitions on the hard drive. Figure 8-2. LVM Configuration 67 8. Refer to Figure 8-3 to verify your inputted values: . Two Blank Drives. Leave the Fixed size (the default) radio button selected in the Additional Size Options area. Select /boot from the Mount Point pulldown menu. or formatted clean. If other operating systems are already on the system. Leave 100 (the default) in the Size (MB) menu.2. 1. Figure 8-2. refer to the appendix section of the Red Hat Enterprise Linux Installation Guide. shows both drives as raw devices with no partitioning configured. Ready For Configuration Warning The /boot/ partition cannot reside on an LVM volume group because the GRUB boot loader cannot read it. the partition is created as a logical partition. Creating the /boot/ Partition In a typical situation.Chapter 8. For more information on primary versus logical/extended partitions.
2. the remainder of all disk space can be allocated to LVM partitions. Select physical volume (LVM) from the File System Type pulldown menu as shown in Figure 8-5.68 Chapter 8. The following figure displays the boot partition correctly set: Figure 8-4. Creating the LVM Physical Volumes Once the boot partition is created. 2. 1. Creation of the Boot Partition Click OK to return to the main screen. Select New. LVM Configuration Figure 8-3. The first step in creating a successful LVM implementation is the creation of the physical volume(s). . The /boot/ Partition Displayed 8.2.
they share the available free space on the disk. LVM Configuration 69 Figure 8-5. select Fill all space up to (MB) and enter a size in MBs to give range for the physical volume size. 7. Select Force to be a primary partition if you want the partition to be a primary partition. Select Fixed size to make the physical volume the specified size. Enter the size that you want the physical volume to be. select the drive on which the physical volume are created. If you have multiple drives. The following figure shows both drives completed after the repeated process: . For Allowable Drives. 4. Click OK to return to the main screen. if you want the volume group to span over more than one drive.Chapter 8. Creating a Physical Volume 3. If you make more than one growable. For example. Repeat these steps to create as many physical volumes as needed for your LVM setup. 8. all drives are selected. You cannot enter a mount point yet (you can once you have created all your physical volumes and then all volume groups). A physical volume must be constrained to one drive. 5. or select Fill to maximum allowable size to make it grow to fill all available space on the hard disk. 6. create a physical volume on each of the drives. and you must deselect all but one drive.
however. You can have multiple logical volume groups. Creating an LVM Volume Group .70 Chapter 8. the size of the logical volumes shown is correct. Note There is overhead disk space reserved in the logical volume group. the volume groups can be created: 1.3. but a physical volume can only be in one volume group. Click the LVM button to collect the physical volumes into volume groups.2. Figure 8-7. LVM Configuration Figure 8-6. A volume group is basically a collection of physical volumes. Two Physical Volumes Created 8. The summation of the physical volumes may not equal the size of the volume group. Creating the LVM Volume Groups Once all the physical volumes are created.
Chapter 8. Creating a Logical Volume Repeat these steps for each volume group you want to create. 71 3. Tip You may want to leave some free space in the logical volume group so you can expand the logical volumes later. logical volume sizes must be divisible by 32 MBs. The default automatic configuration does not do this. Select which physical volumes to use for the volume group. . Change the Volume Group Name if desired. If you enter a size that is not a unit of 32 MBs. All logical volumes inside the volume group must be allocated in physical extent units. 4. Creating the LVM Logical Volumes Create logical volumes with mount points such as /. LVM Configuration 2. the installation program automatically selects the closest size in units of 32 MBs. By default.2.4. To add a logical volume. A dialog window as shown in Figure 8-8 appears. click the Add button in the Logical Volumes section. /home/. It is not recommended that you change this setting. thus. Figure 8-8. but this manual configuration example does — approximately 1 GB is left as free space for future expansion. Remember that /boot cannot be a logical volume. and swap space. 8. the physical extent is set to 32 MB.
LVM Configuration Figure 8-9. The following figure shows the final manual configuration: Figure 8-10. Final Manual Configuration . Pending Logical Volumes Click OK to apply the volume group and all associated logical volumes.72 Chapter 8.
When the data is to be read.3. The whole subsystem is connected to the host via a normal SCSI controller and appears to the host as a single disk. . What is RAID? The basic idea behind RAID is to combine multiple small. the data must first be broken into consistently-sized chunks (often 32K or 64K in size. but then you add them to the RAID controller's configuration.Chapter 9. Redundant Array of Independent Disks (RAID) 9. Hardware RAID The hardware-based array manages the RAID subsystem independently from the host and presents to the host only a single disk per RAID array. In these cases. and the operating system never knows the difference.1. giving the illusion that the multiple drives in the array are actually one large drive.3. This array of drives appears to the computer as a single logical storage unit or drive. To do this. RAID uses techniques such as disk striping (RAID Level 0). Hardware RAID versus Software RAID There are two possible RAID approaches: Hardware RAID and Software RAID. Each chunk is then written to a hard drive in the RAID array according to the RAID level used. although different sizes can be used). RAID is a method in which information is spread across several disks.1. The underlying concept of RAID is that data may be distributed across each drive in the array in a consistent manner. and disk striping with parity (RAID Level 5) to achieve redundancy. inexpensive disk drives into an array to accomplish performance or redundancy goals not attainable with one large and expensive drive. Primary reasons to use RAID include: • • • Enhanced speed Increased storage capacity using a single virtual disk Lessened impact of a disk failure 9. lower latency and/or to increase bandwidth for reading or writing to disks. An example of a Hardware RAID device would be one that connects to a SCSI controller and presents the RAID arrays as a single SCSI drive. and to maximize the ability to recover from hard disk crashes. you plug the drives into the RAID controller just like you would a SCSI controller. Who Should Use RAID? Those who need to keep large quantities of data on hand (such as system administrators) would benefit by using RAID technology. the process is reversed. 9. 9. An external RAID system moves all RAID handling "intelligence" into a controller located in the external disk subsystem.2. RAID controllers also come in the form of cards that act like a SCSI controller to the operating system but handle all of the actual drive communications themselves. disk mirroring (RAID level 1).
4. It offers the cheapest possible solution. leaving a "mirrored" copy on each disk.2. These RAID types are defined as follows: • Level 0 — RAID level 0. Software RAID also works with cheaper IDE disks as well as SCSI disks. For information on configuring Software Chapter 10 Software RAID Configuration. including levels 0." has been used longer than any other form of RAID. Software RAID performance can excel against Hardware RAID. often called "striping. Redundant Array of Independent Disks (RAID) 9. which wastes drive space. and linear. Level 1 — RAID level 1. Mirroring remains popular due to its simplicity and high level of data availability. For example. Level 1 provides very good data reliability and improves performance for readintensive applications but at a relatively high cost. RAID level 1 comes at a high cost because you write the same information to all of the disks in the array. • 1. . The MD driver in the Linux kernel is an example of a RAID solution that is completely hardware independent. as expensive disk controller cards or hot-swap chassis 1 are not required. 1." is a performance-oriented striped data mapping technique. 2. This means the data being written to the array is broken down into strips and written across the member disks of the array. Level 1 provides redundancy by writing identical data to each member disk of the array. A hot-swap chassis allows you to remove a hard drive without having to power-down your system. here are the most important features: • • • • • • Threaded rebuild process Kernel-based configuration Portability of arrays between Linux machines without reconstruction Backgrounded array reconstruction using idle system resources Hot-swappable drive support Automatic CPU detection to take advantage of certain CPU optimizations 9. allowing high I/O performance at low inherent cost but provides no redundancy. you have 80G total but are only able to access 40G of that 80G. 2 The storage capacity of the level 1 array is equal to the capacity of one of the mirrored hard disks in a Hardware RAID or one of the mirrored partitions in a Software RAID. 5.3. RAID during installation.74 Chapter 9. The performance of a software-based array is dependent on the server CPU performance and load. Software RAID Software RAID implements the various RAID levels in the kernel disk (block device) code. The other 40G acts like a mirror of the first 40G. Level 1 operates with two or more disks that may use parallel access for high data-transfer rates when reading but more commonly operate independently to provide high I/O transaction rates. RAID Levels and Linear Support RAID supports various configurations. if you have RAID level 1 set up so that your root ( /) partition exists on two 40G drives. With today's fast CPUs. 4. The storage capacity of a level 0 array is equal to the total capacity of the member disks in a Hardware RAID or the total capacity of member partitions in a Software RAID. refer to the For those interested in learning more about what Software RAID has to offer. or "mirroring.
minus the size of one of the partitions if they are of equal size. as it is unlikely that any I/O operations will be split between member drives. minus the size of one of the partitions if they are of equal size. The storage capacity of Hardware RAID level 5 is equal to the capacity of member disks. This information can then be used to reconstruct data when one disk in the array fails. Although RAID level 4 is an option in some RAID partitioning schemes. Parity information is calculated based on the contents of the rest of the member disks in the array. Because the dedicated parity disk represents an inherent bottleneck. The capacity is the total of all member disks. minus the capacity of one member disk. The reconstructed data can then be used to satisfy I/O requests to the failed disk before it is replaced and to repopulate the failed disk after it has been replaced. In linear RAID. but level 5 has more advantages. As with level 4. Redundant Array of Independent Disks (RAID) • 75 Level 4 — Level 4 uses parity 3 concentrated on a single disk drive to protect data. going to the next drive only when the first is completely filled. it is not an option allowed in Red Hat Enterprise Linux RAID installations. level 4 is not supported. in fact. Level 5 is often used with write-back caching to reduce the asymmetry. the chunks are allocated sequentially from one member drive. With modern CPUs and Software RAID.Chapter 9. RAID level 5 eliminates the write bottleneck inherent in level 4. minus the capacity of one member disk. the result is asymmetrical performance. . that usually is not a very big problem. By distributing parity across some or all of an array's member disk drives. Linear RAID — Linear RAID is a simple grouping of drives to create a larger virtual drive. • • 3. the entire array cannot be used. decreases reliability — if any one member drive fails. For this reason. 4. The only performance bottleneck is the parity calculation process. level 4 is seldom used without accompanying technologies such as write-back caching. It is better suited to transaction I/O rather than large file transfers. The storage capacity of Software RAID level 5 is equal to the capacity of the member partitions. 4 The storage capacity of Hardware RAID level 4 is equal to the capacity of member disks. This grouping provides no performance benefit. Level 5 — This is the most common type of RAID. with reads substantially outperforming writes. Linear RAID also offers no redundancy and. The storage capacity of Software RAID level 4 is equal to the capacity of the member partitions. RAID level 4 takes up the same amount of space as RAID level 5.
Redundant Array of Independent Disks (RAID) .76 Chapter 9.
and the differences between RAID 0. or during a kickstart installation. Software RAID Configuration Software RAID can be configured during the graphical installation process.1. 1. the same can be done during a text-based installation. and 5. Two 9. the text-based installation process. Creating file systems from the RAID devices. select Manually partition with Disk Druid. .Chapter 10. Note Although the following steps are illustrated during a GUI installation. Optional: Configuring LVM from the RAID devices. Read Chapter 9 Redundant Array of Independent Disks (RAID) first to learn about RAID. 10. An overview of the steps required to configure RAID include: • Applying software RAID partitions to the physical hard drives. using the Disk Druid interface. If you wish to have the boot partition (/boot/) reside on a RAID parition. They detail how to create a simple RAID 1 configuration by implementing multiple RAID devices. the differences between hardware and software RAID. the disk drives are new or are formatted. • • • Creating RAID devices from the software RAID partitions. On the Disk Partitioning Setup screen. it must be on a RAID 1 partition. Refer to Chapter 8 LVM Configuration for more information on configuring LVM after first configuring RAID. This chapter discusses how to configure software RAID during installation. Configuration of software RAID must be done manually in Disk Druid during the installation process. Creating the RAID Partitions In a typical situation.1 GB SCSI drives (/dev/sda and /dev/sdb) are used in the following examples. Both drives are shown as raw devices with no partition configuration in Figure 10-1.
.78 Chapter 10. Two Blank Drives. A software RAID partition must be constrained to one drive. Note that no other RAID options (such as entering a mount point) are available until RAID partitions. 2. Software RAID Configuration Figure 10-1. and you must deselect all but one drive. select the drive on which RAID is to be created. as well as RAID devices. If you have multiple drives. Figure 10-2. all drives are selected. are created. Choose Create a software RAID partition to create a RAID partition as shown in Figure 10-2. For Allowable Drives. choose RAID to enter the software RAID creation screen. In Disk Druid. Ready For Configuration 1. RAID Partition Options 3.
Notice that all the partitions do not have to be RAID partitions.Chapter 10. Repeat these steps to create as many partitions as needed for your RAID setup. 6. which is now ready for RAID device and mount point creation: . If you make more than one partition growable. Figure 10-4 shows successfully allocated space for the RAID 1 configuration (for /boot/). they share the available free space on the disk. If unselected. 5. Select Force to be a primary partition if you want the partition to be a primary partition. leaving the root partition (/). select Fill all space up to (MB) and enter a size in MBs to give range for the partition size. refer to the appendix section of the Red Hat Enterprise Linux Installation Guide. Click OK to return to the main screen. Select Fixed size to make the partition the specified size. Software RAID Configuration 79 Figure 10-3. Adding a RAID Partition 4. For more information on primary versus logical/extended partitions. Enter the size that you want the partition to be. the partition is created as a logical partition. /home/. For example. or select Fill to maximum allowable size to make it grow to fill all available space on the hard disk. If other operating systems are already on the system. A primary partition is one of the first four partitions on the hard drive. you can configure only the /boot/ partition as a software RAID device. unselecting this option should be considered. and swap as regular file systems. 7.
80 Chapter 10. Select Create a RAID device. RAID 1 Partitions Ready. RAID Options 3.2. 2. Pre-Device and Mount Point Creation 10. Figure 10-5 appears. Figure 10-5. Creating the RAID Devices and Mount Points Once you have all of your partitions created as software RAID partitions. where you can make a RAID device and assign a mount point. Select the RAID button on the Disk Druid main partitioning screen (refer to Figure 10-5). the following steps create the RAID device and mount point: 1. . Software RAID Configuration Figure 10-4. Figure 10-6 appears. Next.
The /boot/ Mount Error 8. the spare is automatically used as a replacement. it must be RAID level 1 and must use one of the first two drives (IDE first. continue on with the following instructions. If configuring RAID 1 or RAID 5. You can choose from RAID 0. 6. If you need assistance in determining which RAID level to implement. specify the number of spare partitions. The RAID partitions created appear in the RAID Members list. and it must use one of the first two drives (IDE first. select physical volume (LVM) and then refer to Chapter 8 LVM Configuration. . Choose your RAID level.Chapter 10. and RAID 5. Select a device name such as md0 for the RAID device. RAID 1. If a software RAID partition fails. Note If you are making a RAID partition of /boot/. SCSI second). At this point you can either configure a dynamic LVM file system or a traditional static ext2/ext3 file system. If you are not creating a seperate RAID partition of /boot/. 9. Software RAID Configuration 81 Figure 10-6. 7. Enter a mount point. Select which of these partitions should be used to create the RAID device. and you are making a RAID partition for the root file system ( /). Select the partitions for the RAID device and the partition(s) for the spare(s). Choose the file system type for the partition. Making a RAID Device and Assigning a Mount Point 4. For each spare you want to specify. SCSI second). you must choose RAID level 1. 5. For more information on configuring LVM on a RAID device. Figure 10-7. If LVM is not required. refer to Chapter 9 Redundant Array of Independent Disks (RAID). you must create an additional software RAID partition (in addition to the partitions for the RAID device).
the RAID device appears in the Drive Summary list. After completing the entire configuration. 11. /home/. the figure as shown in Figure 10-8 resembles the default configuration.82 Chapter 10. and mount points. except for the use of RAID. . Software RAID Configuration 10. Final Sample RAID Configuration The figure as shown in Figure 10-9 is an example of a RAID and LVM configuration. After clicking OK. such as the root partition (/). Figure 10-8. Repeat this chapter's entire process for configuring additional partitions. devices. or swap.
. Final Sample RAID With LVM Configuration You can continue with your installation process. Software RAID Configuration 83 Figure 10-9. Refer to the Red Hat Enterprise Linux Installation Guide for further instructions.Chapter 10.
84 Chapter 10. Software RAID Configuration .
a swap file. the size of your swap should be equal to the amount of physical RAM above 2 GB. Swap space is located on hard drives. Important File systems and LVM2 volumes assigned as swap space cannot be in use when being modified. while one with 3 GB of physical RAM would have 5 GB of swap. Refer to Chapter 5 Basic System Recovery for instructions on booting into rescue mode. you may upgrade the amount of RAM in your system from 128 MB to 256 MB. Swap space can be a dedicated swap partition (recommended). For example. it should not be considered a replacement for more RAM. . Adding Swap Space Sometimes it is necessary to add more swap space after installation. For physical RAM above 2 GB. which have a slower access time than physical memory. While swap space can help machines with a small amount of RAM. When prompted to mount the file system.2. deciding on the amount of swap to allocate to Red Hat Enterprise Linux is more of an art than a science. For example. Using this basic formula. as well as no amount of swap should be allocated and used by the kernel. so hard rules are not possible. and then follow the instructions (for each scenario) in the remainder of this chapter. What is Swap Space? Swap space in Linux is used when the amount of physical memory (RAM) is full. no system processes can be assigned the swap space. or a combination of swap partitions and swap files. but there is only 256 MB of swap space. inactive pages in memory are moved to the swap space. Swap Space 11.Chapter 11. The best way to achieve swap space modifications is to boot your system in rescue mode. If the system needs more memory resources and the RAM is full. Each system's most used applications should be accounted for when determining swap size. The size of your swap should be equal to twice your computer's physical RAM for up to 2 GB of physical RAM. 11. a system with 2 GB of physical RAM would have 4 GB of swap. Use the free and cat /proc/swaps commands to verify how much and where swap is in use. It might be advantageous to increase the amount of swap space to 512 MB if you perform memory-intense operations or run applications that require a large amount of memory. Note Unfortunately. The size of your swap should never less than 32 MB. select Skip.1.
create a new swap file. Setup the swap file with the command: mkswap /swapfile . Disable swapping for the associated logical volume: # swapoff -v /dev/VolGroup00/LogVol01 2. Swap Space You have three options: create a new swap partition. Creating an LVM2 Logical Volume for Swap To add a swap volume group (assuming /dev/VolGroup00/LogVol02 is the swap volume you want to add): 1.86 Chapter 11. Enable the extended logical volume: # swapon -va 5.2. 2. Enable the extended logical volume: 5. Creating a Swap File To add a swap file: 1. Extending Swap on an LVM2 Logical Volume To extend an LVM2 swap logical volume (assuming /dev/VolGroup00/LogVol01 is the volume you want to extend): 1. Resize the LVM2 logical volume by 256 MB: # lvm lvresize /dev/VolGroup00/LogVol01 -L +256M 3.1. Add the following entry to the /etc/fstab file: /dev/VolGroup00/LogVol02 # swapon -va swap swap defaults 0 0 4. 11. For example.2.2. type the following command with count being equal to the desired block size: dd if=/dev/zero of=/swapfile bs=1024 count=65536 3. Create the LVM2 logical volume of size 256 MB: # lvm lvcreate VolGroup00 -n LogVol02 -L 256M 2. At a shell prompt as root.3. Format the new swap space: # mkswap /dev/VolGroup00/LogVol02 3. Format the new swap space: # mkswap /dev/VolGroup00/LogVol01 4. Determine the size of the new swap file in megabytes and multiply by 1024 to determine the number of blocks. the block size of a 64 MB swap file is 65536.2. It is recommended that you extend an existing logical volume. Test that the logical volume has been extended properly: # cat /proc/swaps # free 11. or extend swap on an existing LVM2 logical volume. Test that the logical volume has been extended properly: # cat /proc/swaps # free 11.
verify it is enabled by viewing the output of the command cat /proc/swaps or free. Enable the extended logical volume: # swapon -va 5. Remove the following entry from the /etc/fstab file: .3. 11. 6. it enables the new swap file. Refer to Chapter 5 Basic System Recovery for instructions on booting into rescue mode. Removing Swap Space Sometimes it can be prudent to reduce swap space after installation. Remove the LVM2 logical volume of size 512 MB: # lvm lvremove /dev/VolGroup00/LogVol02 3. When prompted to mount the file system. For example. You have three options: remove an entire LVM2 logical volume used for swap. Removing an LVM2 Logical Volume for Swap The swap logical volume cannot be in use (no system locks or processes on the volume). remove a swap file. Disable swapping for the associated logical volume: # swapoff -v /dev/VolGroup00/LogVol02 2. or reduce swap space on an existing LVM2 logical volume. Disable swapping for the associated logical volume: # swapoff -v /dev/VolGroup00/LogVol01 2.3. say you downgraded the amount of RAM in your system from 1 GB to 512 MB. since the larger 2 GB could be wasting disk space. select Skip.1. Reduce the LVM2 logical volume by 512 MB: # lvm lvreduce /dev/VolGroup00/LogVol01 -L -512M 3. Reducing Swap on an LVM2 Logical Volume To reduce an LVM2 swap logical volume (assuming /dev/VolGroup00/LogVol01 is the volume you want to extend): 1. To enable it at boot time. Format the new swap space: # mkswap /dev/VolGroup00/LogVol01 4. Swap Space 4.Chapter 11. edit /etc/fstab to include the following entry: /swapfile swap swap defaults 0 0 The next time the system boots. 11. but there is 2 GB of swap space still assigned.3.2. After adding the new swap file and enabling it. The easiest way to achieve this it to boot your system in rescue mode. It might be advantageous to reduce the amount of swap space to 1 GB. To remove a swap volume group (assuming /dev/VolGroup00/LogVol02 is the swap volume you want to remove): 1. To enable the swap file immediately but not automatically at boot time: swapon /swapfile 87 5. Test that the logical volume has been reduced properly: # cat /proc/swaps # free 11.
At a shell prompt as root.4. and then follow the steps for adding swap space. Moving Swap Space To move swap space from one location to another. follow the steps for removing swap space.88 /dev/VolGroup00/LogVol02 # cat /proc/swaps # free swap swap defaults Chapter 11. Removing a Swap File To remove a swap file: 1. . execute the following command to disable the swap file (where /swapfile is the swap file): # swapoff -v /swapfile 2.3. Remove the actual file: # rm /swapfile 11. 3.3. Test that the logical volume has been extended properly: 11. Remove its entry from the /etc/fstab file. Swap Space 0 0 4.
or add partitions from free space or additional hard drives. if the drive does not contain any partitions in use (system processes that use or lock the file system from being unmounted). or resize a partition. This chapter discusses how to use parted to perform file system tasks. The (parted) prompt is displayed. remove. 12. at a shell prompt as root. you can unmount them with the umount command and turn off all the swap space on the hard drive with the swapoff command. and swap space cannot be enabled). To start parted. Refer to Chapter 5 Basic System Recovery for instructions on booting into rescue mode. Command check minor-num cp from to Description Perform a simple check of the file system Copy file system from one partition to another. If you want to create.3 File Systems. The utility parted allows users to perform these tasks... change the size of the partitions.. where /dev/sda is the device name for the drive you want to configure. The sections that follow explain some of them in more detail. If you want to view the system's disk space usage or monitor the disk space usage. The easiest way to achieve this it to boot your system in rescue mode. the device cannot be in use (partitions cannot be mounted. type the command parted /dev/sda. remove partitions.1. Data could be overwritten by writing to the wrong partition because the partition table and partitions mounted do not match. Alternately.. Type help to view a list of available commands. Standard Partitions using parted Many users need to view the existing partition table. You must have the parted package installed to use the parted utility.. Managing Disk Storage Introduction to different methods.Chapter 12. select Skip... refer to Section 40. from and to are the minor numbers of the partitions Display list of available commands Create a disk label for the partition table Create a file system of type file-system-type Make a partition without creating a new file system Make a partition and create the specified file system Move the partition help mklabel label mkfs minor-num file-system-type mkpart part-type fs-type start-mb end-mb mkpartfs part-type fs-type start-mb end-mb move minor-num start-mb end-mb . The partition table should not be modified while in use because the kernel may not properly recognize the changes. Table 12-1 contains a list of commonly used parted commands. When prompted to mount the file system.
677 primary linux-swap 4 6361. root. Viewing the Partition Table After starting parted. lvm. The Type is one of primary.031 101. linux-swap.232 extended lba 5 760.850 primary linux-swap 3 611. or lba.677 8675. minor number 3 refers to the swap. or xfs. type the following command to view the partition table: print A table similar to the following appears: Disk geometry for /dev/sda: 0.975 primary ext3 boot 2 101.727 extended 5 6361. . swap.90 Command name minor-num name print quit rescue start-mb end-mb resize minor-num start-mb end-mb rm minor-num select device set minor-num flag state Chapter 12.1.492 megabytes Disk label type: msdos Minor Start End Type Filesystem Flags 1 0. minor number 2 refers to the root file system (/).708 7357.754 primary ext3 3 5098.975 primary ext3 boot 2 101.895 logical ext3 Disk geometry for /dev/hda: 0. jfs. fat16.031 101. ext3. the partition with minor number 1 corresponds to /dev/sda1.232 logical ext3 The first line displays the size of the disk. state is either on or off Table 12-1. hp-ufs. and the remaining output shows the partition table.891 9758.975 5098. the second line displays the disk label type. hfs.1. fat32. which can be one of ext2. or logical. minor number 1 refers to the /boot/ file system. hidden. and minor number 5 refers to the /home/ file system. sun-ufs.891 primary ext3 4 760. parted commands 12.922 9758. Available flags are boot. Managing Disk Storage Description Name the partition for Mac and PC98 disklabels only Display the partition table Quit parted Rescue a lost partition from start-mb to end-mb Resize the partition from start-mb to end-mb Remove the partition Select a different device to configure Set the flag on a partition. the Minor number is the partition number.000-8678. reiserfs. extended. raid. The Filesystem is the file system type.000-9765. The Flags column lists the flags set for the partition. In the partition table.789 megabytes Disk label type: msdos Minor Start End Type Filesystem Flags 1 0.755 6361. In this example.975 611. For example.851 760. ntfs. The Start and End values are in megabytes.
12.1. you can have three primary partitions. determine the start and end points of the new partition and what partition type it should be.1. you can view its partition table or configure it. where /dev/sda is the device on which to create the partition: parted /dev/sda View the current partition table to determine if there is enough free space: print If there is not enough free space. For an overview of disk partitions. Thus. so review the command before executing to it. Creating a Partition Warning Do not attempt to create a partition on a device that is in use. Start parted. refer to the appendix An Introduction to Disk Partitions in the Red Hat Enterprise Linux Installation Guide. mkpartfs works for file system type linux-swap. . Refer to Section 12.1. Making the Partition From the partition table. boot into rescue mode (or unmount any partitions on the device and turn off any swap space on the device).2. use the select command followed by the device name such as /dev/sda. You can only have four primary partitions (with no extended partition) on a device. and multiple logical partitions within the extended. parted does not support creating an ext3 file system.4 Resizing a Partition for details. 12. one extended partition. Before creating a partition. The changes start taking place as soon as you press [Enter]. Managing Disk Storage 91 Tip To select a different device without having to restart parted. For example. the file system is created after the partition is created. to create a primary partition with an ext3 file system from 1024 megabytes until 2048 megabytes on a hard drive type the following command: mkpart primary ext3 1024 2048 Tip If you use the mkpartfs command instead.1. Then. if you wish to create an ext3 file system. If you need more than four partitions.Chapter 12.2. use mkpart and create the file system with the mkfs command as described later. However. you can resize an existing partition.
Chapter 12. Managing Disk Storage
After creating the partition, use the print command to confirm that it is in the partition table with the correct partition type, file system type, and size. Also remember the minor number of the new partition so that you can label it. You should also view the output of
cat /proc/partitions
to make sure the kernel recognizes the new partition.
220.127.116.11. Formating the Partition
The partition still does not have a file system. Create the file system:
/sbin/mkfs -t ext3 /dev/sda6
Warning Formatting the partition permanently destroys any data that currently exists on the partition.
126.96.36.199. Labeling the Partition
Next, give the partition a label. For example, if the new partition is /dev/sda6 and you want to label it /work:
e2label /dev/sda6 /work
By default, the installation program uses the mount point of the partition as the label to make sure the label is unique. You can use any label you want.
18.104.22.168. Creating the Mount Point
As root, create the mount point:
mkdir /work
22.214.171.124. Add to /etc/fstab
As root, edit the /etc/fstab file to include the new partition. The new line should look similar to the following:
LABEL=/work /work ext3 defaults 1 2
The first column should contain LABEL= followed by the label you gave the partition. The second column should contain the mount point for the new partition, and the next column should be the file system type (for example, ext3 or swap). If you need more information about the format, read the man page with the command man fstab. If the fourth column is the word defaults, the partition is mounted at boot time. To mount the partition without rebooting, as root, type the command:
mount /work
Chapter 12. Managing Disk Storage
12.1.3. Removing a Partition
Warning Do not attempt to remove a partition on a device that is in use.
Before removing a partition, boot into rescue mode (or unmount any partitions on the device and turn off any swap space on the device). Start parted, where /dev/sda is the device on which to remove the partition:
parted /dev/sda
View the current partition table to determine the minor number of the partition to remove:
Remove the partition with the command rm. For example, to remove the partition with minor number 3:
rm 3
The changes start taking place as soon as you press [Enter], so review the command before committing to it. After removing the partition, use the print command to confirm that it is removed from the partition table. You should also view the output of
cat /proc/partitions
to make sure the kernel knows the partition is removed. The last step is to remove it from the /etc/fstab file. Find the line that declares the removed partition, and remove it from the file.
12.1.4. Resizing a Partition
Warning Do not attempt to resize a partition on a device that is in use.
Before resizing a partition, boot into rescue mode (or unmount any partitions on the device and turn off any swap space on the device). Start parted, where /dev/sda is the device on which to resize the partition:
parted /dev/sda
View the current partition table to determine the minor number of the partition to resize as well as the start and end points for the partition:
Chapter 12. Managing Disk Storage
Warning The used space of the partition to resize must not be larger than the new size.
To resize the partition, use the resize command followed by the minor number for the partition, the starting place in megabytes, and the end place in megabytes. For example:
resize 3 1024 2048
After resizing the partition, use the print command to confirm that the partition has been resized correctly, is the correct partition type, and is the correct file system type. After rebooting the system into normal mode, use the command df to make sure the partition was mounted and is recognized with the new size.
12.2. LVM Partition Management
The following commands can be found by issuing lvm help at a command prompt. Command
dumpconfig formats help lvchange lvcreate lvdisplay lvextend lvmchange lvmdiskscan lvmsadc lvmsar lvreduce lvremove lvrename lvresize lvs lvscan pvchange pvcreate
Description Dump the active configuration List the available metadata formats Display the help commands Change the attributes of logical volume(s) Create a logical volume Display information about a logical volume Add space to a logical volume Due to use of the device mapper, this command has been deprecated List devices that may be used as physical volumes Collect activity data Create activity report Reduce the size of a logical volume Remove logical volume(s) from the system Rename a logical volume Resize a logical volume Display information about logical volumes List all logical volumes in all volume groups Change attributes of physical volume(s) Initialize physical volume(s) for use by LVM
Chapter 12. Managing Disk Storage Command
pvdata pvdisplay pvmove pvremove pvresize pvs pvscan segtypes vgcfgbackup vgcfgrestore vgchange vgck vgconvert vgcreate vgdisplay vgexport vgextend vgimport vgmerge vgmknodes vgreduce vgremove vgrename vgs vgscan vgsplit version
95 Description Display the on-disk metadata for physical volume(s) Display various attributes of physical volume(s) Move extents from one physical volume to another Remove LVM label(s) from physical volume(s) Resize a physical volume in use by a volume group Display information about physical volumes List all physical volumes List available segment types Backup volume group configuration Restore volume group configuration Change volume group attributes Check the consistency of a volume group Change volume group metadata format Create a volume group Display volume group information Unregister a volume group from the system Add physical volumes to a volume group Register exported volume group with system Merge volume groups Create the special files for volume group devices in /dev/ Remove a physical volume from a volume group Remove a volume group Rename a volume group Display information about volume groups Search for all volume groups Move physical volumes into a new volume group Display software and driver version information
Table 12-2. LVM commands
Chapter 12. Managing Disk Storage
Chapter 13.
Implementing Disk Quotas
Disk space can be restricted by implementing disk quotas which alert a system administrator is alerted before a user consumes too much disk space or a partition becomes full. Disk quotas can be configured for individual users as well as user groups. This kind of flexibility makes it possible to give each user a small quota to handle "personal" files (such as email and reports), while allowing the projects they work on to have more sizable quotas (assuming the projects are given their own groups). In addition, quotas can be set not just to control the number of disk blocks consumed but to control the number of inodes (data structures that contain information about files in UNIX file systems). Because inodes are used to contain file-related information, this allows control over the number of files that can be created. The quota RPM must be installed to implement disk quotas. For more information on installing RPM packages, refer to Part III Package Management.
13.1. Configuring Disk Quotas
To implement disk quotas, use the following steps: 1. Enable quotas per file system by modifying the /etc/fstab file. 2. Remount the file system(s). 3. Create the quota database files and generate the disk usage table. 4. Assign quota policies. Each of these steps is discussed in detail in the following sections.
13.1.1. Enabling Quotas
As root, using a text editor, edit the /etc/fstab file. Add the usrquota and/or grpquota options to the file systems that require quotas:
/dev/VolGroup00/LogVol00 LABEL=/boot none none none none /dev/VolGroup00/LogVol02 /dev/VolGroup00/LogVol01 . . . / /boot /dev/pts /dev/shm /proc /sys /home swap ext3 ext3 devpts tmpfs proc sysfs ext3 swap defaults 1 1 defaults 1 2 gid=5,mode=620 0 0 defaults 0 0 defaults 0 0 defaults 0 0 defaults,usrquota,grpquota defaults 0 0
1 2
In this example, the /home file system has both user and group quotas enabled.
Chapter 13. Implementing Disk Quotas
Note The following examples assume that a separate /home partition was created during the installation of Red Hat Enterprise Linux. Although not ideal, the root (/) partition (the installation default created partition) can be used for setting quota policies in the /etc/fstab file.
13.1.2. Remounting the File Systems
After adding the usrquota and/or grpquota options, remount each file system whose fstab entry has been modified. If the file system is not in use by any process, use one of the following methods:
• •
Issue the umount command followed by the mount command to remount the file system. Issue the mount -o remount /home command to remount the file system.
If the file system is currently in use, the easiest method for remounting the file system is to reboot the system.
13.1.3. Creating the Quota Database Files
After each quota-enabled file system is remounted, the system is capable of working with disk quotas. However, the file system itself is not yet ready to support quotas. The next step is to run the quotacheck command. The quotacheck command examines quota-enabled file systems and builds a table of the current disk usage per file system. The table is then used to update the operating system's copy of disk usage. In addition, the file system's disk quota files are updated. To create the quota files (aquota.user and aquota.group) on the file system, use the -c option of the quotacheck command. For example, if user and group quotas are enabled for the /home file system, create the files in the /home directory:
quotacheck -cug /home
The -c option specifies that the quota files should be created for each file system with quotas enabled, the -u option specifies to check for user quotas, and the -g option specifies to check for group quotas. If neither the -u or -g options are specified, only the user quota file is created. If only -g is specified, only the group quota file is created. After the files are created, run the following command to generate the table of current disk usage per file system with quotas enabled:
quotacheck -avug
The options used are as follows:
• a • v • u • g
— Check all quota-enabled, locally-mounted file systems — Display verbose status information as the quota check proceeds — Check user disk quota information — Check group disk quota information
Implementing Disk Quotas 99 After quotacheck has finished running. no further disk space can be used. A hard limit is the absolute maximum amount of disk space that a user or group can use. The second column shows how many blocks the user is currently using. To change the editor. The soft limit defines the maximum amount of disk space that can be used. Once this limit is reached. However. That time is known as the grace period. that limit is not set.4. 13. set the EDITOR environment variable in your ~/. change the desired limits. The grace period can be expressed in seconds. the soft limit can be exceeded for a certain amount of time. The next two columns are used to set soft and hard block limits for the user on the file system. In the text editor. the following is shown in the editor configured as the default for the system: Disk quotas for user testuser (uid 501): Filesystem blocks soft /dev/VolGroup00/LogVol02 440436 0 hard 0 inodes 37418 soft 0 hard 0 Note The text editor defined by the EDITOR environment variable is used by edquota. weeks. unlike the hard limit. or months. as root in a shell prompt. Assigning Quotas per User The last step is assigning the disk quotas with the edquota command. To configure the quota for a user. execute the command: edquota username Perform this step for each user who needs a quota. use the command: quota testuser . If any of the values are set to 0. minutes. For example.Chapter 13. if a quota is enabled in /etc/fstab for the /home partition (/dev/VolGroup00/LogVol02) and the command edquota testuser is executed. The inodes column shows how many inodes the user is currently using.1. the quota files corresponding to the enabled quotas (user and/or group) are populated with data for each quota-enabled locally-mounted file system such as /home. The last two columns are used to set the soft and hard inode limits for the user on the file system. The first column is the name of the file system that has a quota enabled for it. days. hours.bash_profile file to the full path of the editor of your choice. For example: Disk quotas for user testuser (uid 501): Filesystem blocks soft /dev/VolGroup00/LogVol02 440436 500000 hard 550000 inodes 37418 soft 0 hard 0 To verify that the quota for the user has been set.
1. save the changes to the file. For example. use the command: edquota -t Like the other edquota commands. they need some maintenance — mostly in the form of watching to see if the quotas are exceeded and making sure the quotas are accurate.2. if users repeatedly exceeds their quotas or consistently reaches their soft limits. to set a group quota for the devel group (the group must exist prior to setting the group quota). only group quotas are disabled.6.100 Chapter 13. 13.1. this one opens the current quotas for the file system in the text editor: Grace period before enforcing soft limits for users: Time units may be: days. only the user quotas are disabled. Assigning Quotas per Group Quotas can also be assigned on a per-group basis. The administrator can either help the user determine how to use less disk space or increase the user's disk quota if needed. use the command: edquota -g devel This command displays the existing quota for the group in the text editor: Disk quotas for group devel (gid 505): Filesystem blocks soft /dev/VolGroup00/LogVol02 440400 0 hard 0 inodes 37418 soft 0 hard 0 Modify the limits.5. save the file. and exit the text editor. a system administrator has a few choices to make depending on what type of users they are and how much disk space impacts their work. Enabling and Disabling It is possible to disable quotas without setting them to be 0. Assigning Quotas per File System To assign quotas based on each file system enabled for quotas. To verify that the group quota has been set. . Implementing Disk Quotas 13. and then configure the quota. Of course. If only -g is specified. To turn all user and group quotas off. minutes. use the command: quota -g devel 13. Managing Disk Quotas If quotas are implemented. hours. 13. or seconds Filesystem Block grace period /dev/mapper/VolGroup00-LogVol02 7days Inode grace period 7days Change the block grace period or inode grace period. use the following command: quotaoff -vaug If neither the -u or -g options are specified.2.1.
2. quotacheck can be run on a regular basis. the first . Reporting on Disk Quotas repquota /home produces this output: Creating a disk usage report entails running the repquota utility.2. Inode grace time: 7days Block limits File limits User used soft hard grace used soft hard grace ---------------------------------------------------------------------root -36 0 0 4 0 0 kristin -540 0 0 125 0 0 testuser -. 13. use the quotaon command with the same options. and the second represents the inode limit. Keeping Quotas Accurate Whenever a file system is not unmounted cleanly (due to a system crash.daily .Chapter 13. for example). to enable user and group quotas for all file systems. If a soft limit has been exceeded. only group quotas are enabled. none appears in its place. The grace columns are normally blank. If only -g is specified. such as /home. However. For example. use the command: repquota -a While the report is easy to read.1 Enabling Quotas): quotacheck -avug The easiest way to run it periodically is to use cron. a + appears in place of the corresponding -.2. even if the system has not crashed. Running the following command periodically keeps the quotas more accurate (the options used have been described in Section 13. a few points should be explained. 13. the column contains a time specification equal to the amount of time remaining on the grace period. use the following command: quotaon -vaug 101 To enable quotas for a specific file system. For example. the command *** Report for user quotas on device /dev/mapper/VolGroup00-LogVol02 Block grace time: 7days.1.hourly • /etc/cron.displayed after each user is a quick way to determine whether the block or inode limits have been exceeded. either use the crontab -e command to schedule a periodic quotacheck or place a script that runs quotacheck in any one of the following directories (using whichever interval best matches your needs): • /etc/cron. The -.represents the block limit. Implementing Disk Quotas To enable quotas again. use the following command: quotaon -vug /home If neither the -u or -g options are specified.440400 500000 550000 37418 0 0 To view the disk usage report for all (option -a) quota-enabled file systems. If the grace period has expired. only the user quotas are enabled. it is necessary to run quotacheck.3. If either soft limit is exceeded. As root.
. the cron task should be schedule during a time where the file system(s) are used the least.monthly Chapter 13. this manual contains background information on storage management (including disk quotas) for new Red Hat Enterprise Linux system administrators. edquota. — Available at http://www.weekly • /etc/cron. Red Hat.com/docs/ and on the Documentation CD.3.1. and quotaoff man pages 13. If this time is various for different file systems with quotas. Implementing Disk Quotas The most accurate quota statistics can be obtained when the file system(s) analyzed are not in active use. Thus. Installed Documentation • The quotacheck.3. run quotacheck for each file system at different times with multiple cron tasks.3. quotaon. quota. repquota. 13.102 • /etc/cron.2. Related Books • Red Hat Enterprise Linux Introduction to System Administration. 13. refer to the following resources.redhat. Refer to Chapter 35 Automated Tasks for more information about configuring cron. Inc. Additional Resources For more information on disk quotas.
2. An access ACL is the access control list for a specific file or directory. NFS By default. No special flags are required when accessing or mounting a Samba share. The cp and mv commands copy or move any ACLs associated with files and directories.Chapter 14. if the file system being exported by an NFS server supports ACLs and the NFS client can read ACLs. However. If it is a local ext3 file system. the entry for the partition can include the acl option: LABEL=/work /work ext3 acl 1 2 If an ext3 file system is accessed via Samba and ACLs have been enabled for it. if a file within the directory does not have an access ACL. 14. Along with support in the kernel. To disable ACLs on an NFS share when mounting it on a client. 14. Access Control Lists (ACLs) were implemented. ACLs are utilized by the client system. and all other users for the system. include the no_acl option in the /etc/exports file. it uses the rules of the default ACL for the directory. The Red Hat Enterprise Linux 4 kernel provides ACL support for the ext3 file system and NFSexported file systems. Default ACLs are optional. and retrieve ACL information. the ACLs are recognized because Samba has been compiled with the --with-acl-support option. For example. modify. To disable ACLs on NFS shares when configuring the server.1. . the partition for the file or directory must be mounted with ACL support. the acl package is required to implement ACLs. mount it with the no_acl option via the command line or the /etc/fstab file. A default ACL can only be associated with a directory. if the partition is listed in the /etc/fstab file. remove. different permissions cannot be configured for different users. the group associated with the file. It contains the utilities used to add.1. Thus. 14. these permission sets have limitations. Access Control Lists Files and directories have permission sets for the owner of the file. Setting Access ACLs There are two types of ACLs: access ACLs and default ACLs. it can mounted with the following command: mount -t ext3 -o acl <device-name> <partition> For example: mount -t ext3 -o acl /dev/VolGroup00/LogVol02 /work Alternatively.1. ACLs are also recognized on ext3 file systems accessed via Samba. Mounting File Systems Before using ACLs for a file or directory.
and x for read. The user may be any valid user on the system. o:<perms> Sets the access ACL for users other than the ones in the group for the file. use the -x option and do not specify any permissions: setfacl -x <rules> <files> For example. The group name or GID may be specified. If a file or directory already has an ACL. to remove all permissions from the user with UID 500: setfacl -x u:500 /project/somefile . w. Per group 3. The mask is the union of all permissions of the owning group and all of the user and group entries. the additional rules are added to the existing ACL or the existing rule is modified. Permissions (<perms>) must be a combination of the characters r. Access Control Lists The setfacl utility sets ACLs for files and directories. and execute. Via the effective rights mask 4. The user name or UID may be specified.104 ACLs can be configured: 1. Multiple rules can be specified in the same command if they are separated by commas. For users not in the user group for the file Chapter 14. Per user 2. For example. or others. White space is ignored. m:<perms> Sets the effective rights mask. to give read and write permissions to user andrius: setfacl -m u:andrius:rw /project/somefile To remove all the permissions for a user. Use the -m option to add or modify the ACL of a file or directory: setfacl -m <rules> <files> Rules (<rules>) must be specified in the following formats. and the setfacl command is used. g:<gid>:<perms> Sets the access ACL for a group. The group may be any valid group on the system. write. group. u:<uid>:<perms> Sets the access ACL for a user.
the default ACL is also displayed such as: # file: file # owner: andrius # group: andrius user::rwuser:smoore:r-group::r-mask::r-other::r-default:user::rwx default:user:andrius:rwx default:group::r-x default:mask::rwx default:other::r-x 14. to set the default ACL for the /share/ directory to read and execute for users not in the user group (an access ACL for an individual file can override it): setfacl -m d:o:rx /share 14.3. For all available options. Access Control Lists 105 14. and it has a default ACL. Archiving File Systems With ACLs Warning The tar and dump commands do not backup ACLs. . use the getfacl command: getfacl <filename> It returns output similar to the following: # file: file # owner: andrius # group: andrius user::rwuser:smoore:r-group::r-mask::r-other::r-- If a directory is specified.5. Refer to Table 14-1 for a listing of more commonly used options. For example. however.4.Chapter 14. The star utility is similar to the tar utility in that it can be used to generate archives of files. Setting Default ACLs To set a default ACL. some of its options are different. add d: before the rule and specify a directory instead of a file name. The star package is required to use this utility. Retrieving ACLs To determine the existing ACLs for a file or directory. refer to the star man page.
Displays the least important options. Installed Documentation • acl man page — Description of ACLs . If used with -U and a file in the archive is older than the corresponding file on the file system.6.7. Compatibility with Older Systems If an ACL has been set on any file on a given file system. By default. -t -u -x -help -xhelp -/ -acl Table 14-1. Extracts the files from the archive.106 Option -c -n -r Chapter 14. 14. Replaces files in the archive. they are striped when files are extracted. Updates the archive file.1. Do not strip leading slashes from file names when extracting the files from an archive. The files are written to the end of the archive if they do not exist in the archive or if the files are newer than the files of the same name in the archive. This option only work if the archive is a file or an unblocked tape that may backspace.1 and 4) can check a file system with the ext_attr attribute. This attribute can be seen using the following command: tune2fs -l <filesystem-device> A file system that has acquired the ext_attr attribute can be mounted with older kernels. Older versions refuse to check it. replacing any files with the same path and file name. Command Line Options for star 14. 14. Do not extract the files. The files are written to the end of the archive file. Displays the contents of the archive file. the file is not extracted. Access Control Lists Description Creates an archive file. Displays the most important options. Versions of the e2fsck utility included in version 1.22 and higher of the e2fsprogs package (including the versions in Red Hat Enterprise Linux 2. that file system has the ext_attr attribute. use in conjunction with -x to show what extracting the files does. Additional Resources Refer to the follow resources for more information. When creating or extracting.7. but those kernels do not enforce any ACLs which have been set. archive or restore any ACLs associated with the files and directories.
Chapter 14. Access Control Lists • getfacl • setfacl • star 107 man page — Discusses how to get file access control lists man page — Explains how to set file access control lists man page — Explains more about the star utility and its many options 14.7. Useful Websites • http://acl.at/ — Website for ACLs .bestbits.2.
108 Chapter 14. Access Control Lists .
.................................. upgraded.. 125 ........... Red Hat Network .................. 121 17..........III........... or removed................................. Package Management All software on a Red Hat Enterprise Linux system is divided into RPM packages which can be installed......................................... Table of Contents 15.......................................... 111 16......... This part describes how to manage the RPM packages on a Red Hat Enterprise Linux system using graphical and command line tools...................... Package Management Tool .................................................................... Package Management with RPM ....................
If you prefer a graphical interface. encourages other vendors to use RPM for their own products. RPM allows you to take software source code and package it into source and binary packages for end users. At that . you can upgrade individual components of your system without completely reinstalling. For the end user. Configuration files in packages are preserved across upgrades. You are notified of any anomalies. you can use the Package Management Tool to perform many RPM commands. available for anyone to use. so that you never lose your customizations — something that you cannot accomplish with regular . RPM Design Goals To understand how to use RPM. There are no special upgrade files needed to upgrade a package because the same RPM file is used to install and upgrade the package on your system. Installing. remove.gz files. in-place upgrades of your system. or upgrade an RPM package. RPM is distributable under the terms of the GPL. Inc. it can be helpful to understand RPM's design goals: Upgradability Using RPM. Red Hat. Refer to Chapter 16 Package Management Tool for details. Note Because RPM makes changes to your system. fully-automated. you do not need to reinstall on your machine (as you do with operating systems based on other packaging systems). RPM makes system updates easy. You can do searches through your entire database for packages or just for certain files. If you are worried that you deleted an important file for some package. When you get a new release of an operating system based on RPM (such as Red Hat Enterprise Linux). which runs on Red Hat Enterprise Linux as well as other Linux and UNIX systems. Package Management with RPM The RPM Package Manager (RPM) is an open packaging system.tar. uninstalling. so you can invoke powerful queries and verifications on your system. RPM handles configuration files carefully.1. allowing you to query individual packages quickly and easily. you must be root to install. The files an RPM package contains are in a compressed archive. RPM maintains a database of installed packages and their files. This clear delineation between pristine sources and your patches along with build instructions eases the maintenance of the package as new versions of the software are released. You can also easily find out what package a file belongs to and from where the package came. 15. and upgrading RPM packages can be accomplished with short commands. verify the package. For the developer. During upgrades.Chapter 15. with a custom binary header containing useful information about the package and its contents. System Verification Another powerful feature is the ability to verify packages. so you do not lose your customizations. RPM allows intelligent. Powerful Querying RPM is designed to provide powerful querying options. This process is quite simple and is driven from a single file and optional patches that you create.
Installing RPM packages typically have file names like foo-1.2. if a new version of a program comes out. you do not necessarily have to start from scratch to get it to compile. an error message such as the following is displayed: .. try rpm --help or refer to Section 15..2. are easily visible using this technique. you have the pristine sources along with any patches that were used.html Red Hat Network — Refer to Chapter 17 Red Hat Network for more details on Red Hat Network 15. The file name includes the package name (foo). you can reinstall the package if necessary. but if you are looking for RPM packages built by Red Hat. log in as root and type the following command at a shell prompt: rpm -Uvh foo-1.1.0-1. The goal of keeping sources pristine may only seem important for developers.redhat. Any configuration files that you modified are preserved during reinstallation. and architecture (i386). you must know where to find them. too. the following output is displayed: Preparing. For example.112 Chapter 15.5 Additional Resources for more information on RPM. With RPM. 15. plus complete build instructions. they can be found at the following locations: • • • • The Red Hat Enterprise Linux CD-ROMs The Red Hat Errata Page available at http://www. 15. You can look at the patch to see what you might need to do. All the compiled-in defaults. as distributed by the original authors of the software.0).i386. upgrading. Pristine Sources A crucial design goal was to allow the use of "pristine" software sources.rpm If installation is successful.com/download/mirror. 1:foo ########################################### [100%] ########################################### [100%] As you can see.i386. The signature of a package is checked automatically when installing or upgrading a package.redhat.rpm. For instance.0-1. uninstalling. release (1). querying. This section contains an overview of each mode. The signature confirms that the package was signed by an authorized party. but it results in higher quality software for end users. Using RPM RPM has five basic modes of operation (not counting package building): installing. and all of the changes that were made to get the software to build properly. Package Management with RPM point. An Internet search returns many RPM repositories. and verifying. To install a package.2. RPM prints out the name of the package and then prints a succession of hash marks as the package is installed as a progress meter.2. if the verification of the signature fails. This is an important advantage for several reasons. For complete details and options. Finding RPM Packages Before using an RPM.com/apps/support/errata/ A Red Hat FTP Mirror Site available at http://www. version (1.
0-1. the message contains the word NOKEY such as: warning: V3 DSA signature: NOKEY. the following is displayed: Preparing.0-1 conflicts with file from package bar-2. Package Management with RPM error: V3 DSA signature: BAD.i386. Conflicting Files If you attempt to install a package that contains a file which has already been installed by another package or an earlier version of the same package.1.2. 15. which tells RPM to ignore the error: rpm -ivh --replacepkgs foo-1. header-only.rpm This option is helpful if files installed from the RPM were deleted or if you want the original configuration files from the RPM to be installed. the following is displayed: Preparing. 15..i386.2. Warning If you are installing a kernel package.Chapter 15. Refer to Chapter 37 Manually Upgrading the Kernel for details.0-1 is already installed If the same version you are trying to install is already installed. you can use the --replacepkgs option. Installing packages is designed to be simple. ########################################### [100%] file /usr/bin/foo from install of foo-1.0. you should use rpm -ivh instead.2.2. but you may sometimes see errors.. use the --replacefiles option: rpm -ivh --replacefiles foo-1.rpm .20 To make RPM ignore this error. signature. key ID 0352860f 113 If it is a new... key ID 0352860f If you do not have the appropriate key installed to verify the signature.3 Checking a Package's Signature for more information on checking a package's signature. ########################################### [100%] package foo-1.2. and you ewant to install the package anyway. Package Already Installed If the package of the same version is already installed.0-1. an error message such as the following is displayed: error: Header V3 DSA signature: BAD. key ID 0352860f Refer to Section 15.
rpm -q --redhatprovides bar.rpm If you are installing a package from the Red Hat Enterprise Linux CD-ROM set. You can encounter a dependency error when uninstalling a package if another installed package depends on the one you are trying to remove.. Find the suggested package(s) on the Red Hat Enterprise Linux CD-ROMs or from the Red Hat FTP site (or mirror).20-3.rpm bar-2. 1:foo 2:bar ########################################### [100%] ########################################### [ 50%] ########################################### [100%] If it does not suggest a package to resolve the dependency.i386. output similar to the following is displayed: error: Failed dependencies: bar. depend on other packages.0. To uninstall a package.2 is needed by foo-1.3. it usually suggest the package(s) needed to resolve the dependency. 15. replace foo with the actual package name of the original package.0-1. the name of the package is displayed: bar-2.i386. you can try the --redhatprovides option to determine which package contains the required file. essentially..20-3.2 If the package that contains bar.3. Type the following command at a shell prompt: rpm -e foo Note Notice that we used the package name foo.0-1. Unresolved Dependency RPM packages can.so. use the --nodeps option. not the name of the original package file foo-1.2 is in the installed database from the rpmdb-redhat package.0. output similar to the following is displayed: Preparing. and add it to the command: rpm -ivh foo-1. You need the rpmdb-redhat package installed to use this option.i386.114 Chapter 15.so.i386.rpm.2.rpm To force the installation anyway (which is not recommended since the package may not run correctly).rpm If installation of both packages is successful.so. If you try to install a package which has an unresolved dependency. Package Management with RPM 15. Uninstalling Uninstalling a package is just as simple as installing one.20-3.2. For example: . which means that they require other packages to be installed to run properly.i3184.108.40.206-1 Suggested resolutions: bar-2.
use the --nodeps option.rpm 15.i386. Freshening Freshening a package is similar to upgrading one.4.0-1 (which is newer than foo-1. RPM automatically uninstalls any old versions of the foo package. the output is similar to the following: package foo-2. Similarly. In fact. there would be no other kernel to boot instead. but if the new kernel is unable to boot during your next restart. When a newer version of an already-installed package is processed by RPM's freshen option.conf as /etc/foo. to ensure that your system continues to function properly.2. If RPM thinks you are trying to upgrade to a package with an older version number. Type the following command at a shell prompt: rpm -Fvh foo-1. Type the following command at a shell prompt: rpm -Uvh foo-2.rpm RPM's freshen option checks the versions of the packages specified on the command line against the versions of packages that have already been installed on your system.0. you may see a message like the following: saving /etc/foo. 15. so during an RPM upgrade you can encounter uninstalling and installing errors.i386.Chapter 15.rpm 115 To cause RPM to ignore this error and uninstall the package anyway.20-3. Because RPM performs intelligent upgrading of packages with configuration files.2. This does not affect a running system. use the --oldpackage option: rpm -Uvh --oldpackage foo-1.0-1.rpmsave This message means that your changes to the configuration file may not be forward compatible with the new configuration file in the package.rpm As part of upgrading a package.0-1. Tip You don't want to use the -U option for installing kernel packages because RPM replaces the previous kernel package. unneeded kernel removes the kernel from GRUB. Using the -i option adds the kernel to your GRUB boot menu (/etc/grub. it is upgraded to the newer version. Upgrading Upgrading a package is similar to installing one.i386.conf. Upgrading is really a combination of uninstalling and installing.2-1. so RPM saved your original file and installed a new one. removing an old. You should investigate the differences between the two configuration files and resolve them as soon as possible. which may break the package depending on it. you may want to always use -U to install packages which works even when there are no previous versions of the package installed.0-1) is already installed To force RPM to upgrade anyway.i386. Package Management with RPM error: Failed dependencies: foo is needed by (installed) bar-2.conf). .5. plus one more.
info pages.6. These are called Package Selection Options. version. • -p <packagefile> There are a number of ways to specify what information to display about queried packages. • -a queries all currently installed packages. freshening does the job. sendmail. etc. you do not have to delete any unwanted packages from the group that you downloaded before using RPM. inittab. issue the following command: rpm -Fvh *. description. whether or not an older version of the package was already installed. build date. • -i displays package information including name. RPM's freshen option works for single packages or package groups. vendor. etc. If you use freshening.116 Chapter 15. as an upgrade does install packages.2. READMEs. size.rpm RPM automatically upgrades only those packages that are already installed. RPM's freshen option does not install a package if no previously-installed package of the same name exists. • -l • -s • -d • -c displays a list of files marked as configuration files. you must specify the full path of the file (for example. In this case. displays the list of files that the package contains.).0-1 Note To query a package. displays the state of all the files in the package. For the options that display lists of files. and other miscellaneous information. replace foo with the actual package name. release. The following options are used to select the type of information for which you are searching. If you have just downloaded a large number of different packages. use the following options with -q to specify the package(s) you want to query. install date. displays a list of files marked as documentation (man pages. Querying Use the rpm -q command to query the database of installed packages. passwd. Instead of specifying the package name.cf. The rpm -q foo command displays the package name. /bin/ls). • -f <file> queries the package which owns <file>. add -v to the command to display the lists in a familiar ls -l format.). When specifying a file. and release number of the installed package foo: foo-2. queries the package <packagefile>. These are called Information Query Options. and you only want to upgrade those packages that are already installed on your system. . This differs from RPM's upgrade option. These are the files you change after installation to adapt the package to your system (for example. Package Management with RPM However. 15.
0-1. they are displayed. use your best judgment to determine if you should remove or reinstall the package. examine only the md5sum by typing the following command at a shell prompt (<rpm-file> with file name of the RPM package): rpm -K --nosignature <rpm-file> The message <rpm-file>: md5 OK is displayed.7. The following characters denote failure of certain tests: • 5 • S • L • T • D • U • G • M • ? — MD5 checksum — file size — symbolic link — file modification time — device — user — group — mode (includes permissions and file type) — unreadable file If you see any output. This brief message means that the file was not corrupted by the download. or fix the problem in another way. how trustworthy is the developer who created the package? If the package is signed with the developer's GnuPG key. The command rpm -V verifies a package. there is no output. Package Management with RPM 117 15. Each of the eight characters denotes the result of a comparison of one attribute of the file to the value of that attribute recorded in the RPM database. replace -K with -Kvv in the command. To see a more verbose message. MD5 sum. On the other hand. The format of the output is a string of eight characters (a c denotes a configuration file) and then the file name. A simple use of verifying is rpm -V foo.3. 15. Verifying Verifying a package compares information about files installed from a package with the same information from the original package. Checking a Package's Signature If you wish to verify that a package has not been corrupted or tampered with. Among other things. owner.rpm This command can be useful if you suspect that your RPM databases are corrupt.Chapter 15. If there are any discrepancies. You can use any of the Package Verify Options listed for querying to specify the packages you wish to verify. which verifies that all the files in the foo package are as they were when they were originally installed. and group of each file. If everything verified properly. verifying compares the size. permissions. For example: • • • To verify a package containing a particular file: rpm -Vf /usr/bin/vim To verify ALL installed packages: rpm -Va To verify an installed package against an RPM package file: rpm -Vp foo-1.) means the test passed. type.i386. A single period ( .2. . you know that the developer really is who they say they are.
Importing Keys To verify Red Hat packages. To do so. you could try the following command: rpm -Va If some files are missing or appear to have been corrupted. you must import the Red Hat GPG key. it is a complete and free replacement for the encryption technology of PGP. execute the command: rpm -qa gpg-pubkey* For the Red Hat key. execute the following command at a shell prompt: rpm --import /usr/share/rhn/RPM-GPG-KEY To display a list of all keys installed for RPM verification. an electronic privacy program. GnuPG is a tool for secure communication. Package Management with RPM An RPM package can be signed using Gnu Privacy Guard (or GnuPG).x files as well. • Perhaps you have deleted some files by accident. the following message is displayed: md5 gpg OK.1. Verifying Signature of Packages To check the GnuPG signature of an RPM file after importing the builder's GnuPG key.2. 15. During installation. Impressing Your Friends with RPM RPM is a useful tool for both managing your system and diagnosing and fixing problems. you should probably either re-install the package or uninstall and then re-install the package. GnuPG is capable of decrypting and verifying PGP 5. That means that the signature of the package has been verified and that it is not corrupt. use rpm -qi followed by the output from the previous command: rpm -qi gpg-pubkey-db42a60e-37ea5438 15. That way you can immediately start using GnuPG to verify any packages that you receive from Red Hat. The best way to make sense of all of its options is to look at some examples. the output includes: gpg-pubkey-db42a60e-37ea5438 To display details about a specific key.3. you can authenticate the validity of documents and encrypt/decrypt data to and from other recipients.4. use the following command (replace <rpm-file> with filename of the RPM package): rpm -K <rpm-file> If all goes well. but you are not sure what you deleted. . With GnuPG. GnuPG is installed by default. you must import Red Hat's public key. First.118 Chapter 15. to help you make certain your downloaded package is trustworthy.3. To verify your entire system and see what might be missing. 15.
1. • Perhaps you now want to see what files the crontabs RPM installs. Wed 05 Jan 2005 06:05:25 PM EST.3/NEWS /usr/share/doc/procps-3. You would like to verify the package that owns that program.gz /usr/share/man/man1/snice.1.0-2 • We can combine the above two examples in the following scenario.2.8. but you do not know which package owns paste.gz /usr/share/man/man1/watch.1. You would enter the following: rpm -qlp crontabs-1. • Do you want to find out more information about a particular program? You can try the following command to locate the documentation which came with the package that owns that program: rpm -qdf /usr/bin/free The output would be similar to the following: /usr/share/doc/procps-3. If commands are scheduled. Package Management with RPM • 119 At some point.5. Say you are having problems with /usr/bin/paste.1.gz /usr/share/man/man1/pgrep. uninstall.10-5. To find information about it. To find out which package owns it.10 Vendor: Red Hat.redhat.gz /usr/share/man/man1/top. Enter the following command.gz /usr/share/man/man1/slabtop. Inc.1.6. you might see a file that you do not recognize.8. rpm -Vf /usr/bin/paste and the appropriate package is verified.2.10-7. Release : 7 Build Date: Mon 20 Sep 2004 05:58:10 PM EDT Install Date: (not installed) Build Host: tweety.3/FAQ /usr/share/doc/procps-3.conf. use the following command: rpm -qip crontabs-1.3/TODO /usr/share/man/man1/free.rpm Size : 1004 License: Public Domain Signature : DSA/SHA1.gz /usr/share/man/man1/skill.1.3/BUGS /usr/share/doc/procps-3.1.noarch. but you do not know what it does.build.1.gz • You may find a new RPM.gz /usr/share/man/man1/pmap.rpm The output would be similar to the following: Name : crontabs Relocations: (not relocatable) Version : 1. <http://bugzilla.redhat.gz /usr/share/man/man1/tload.1. enter: rpm -qf /usr/bin/ggv The output would look like the following: ggv-2.1.1.rpm . The cron daemon checks the crontab files to see when particular commands are scheduled to be executed.com/bugzilla> Summary : Root crontab files used to schedule the execution of programs. then it executes them.1.src.10-7.2.gz /usr/share/man/man1/ps.2.gz /usr/share/man/man1/w.gz /usr/share/man/man8/sysctl. Crontab is the program used to install.Chapter 15. Key ID 219180cddb42a60e Packager : Red Hat.gz /usr/share/man/man8/vmstat. or list the tables used to drive the cron daemon.noarch.gz /usr/share/man/man1/uptime.com Group : System Environment/Base Source RPM: crontabs-1. Inc.1.gz /usr/share/man/man5/sysctl. Description : The crontabs package contains root crontab files.gz /usr/share/man/man1/pkill.
http://www. .5.com/mailman/listinfo/rpm-list/ — The RPM mailing list is archived here. As you use it. installing.5. Package Management with RPM These are just a few examples. Refer to the following resources to learn more about RPM. 15. 15. Installed Documentation • rpm --help • man rpm — This command displays a quick reference of RPM parameters. you will find many more uses for RPM. To subscribe. upgrading.rpm. and removing packages.org/ — The RPM website. Related Books • Red Hat RPM Guide by Eric Foster-Johnson.3.com> with the word subscribe in the subject line. 15.5. send mail to <firstname.lastname@example.com. Useful Websites • • http://www.monthly /etc/cron. Wiley.120 The output is similar to the following: /etc/cron.redhat.hourly /etc/cron. — The RPM man page gives more detail about RPM parameters than the rpm --help command.daily /etc/cron. from installing package to building RPMs.weekly /etc/crontab /usr/bin/run-parts Chapter 15. Incorporated — This book is a comprehensive guide to RPM. 15. John & Sons.1. Additional Resources RPM is an extremely complex utility with many options and methods for querying.2.
To start the application. users might want to install or remove packages after installation. Figure 16-1. packages from that group are currently installed. The Package Management Tool allows users to perform these actions. The X Window System is required to run the Package Management Tool. which contain a list of standard packages and extra packages that share common functionality. The same interface automatically appears when you insert the Red Hat Enterprise Linux CD #1 into your computer. and other graphical programs used to connected to the Internet. Because people use their computers differently. For example. the Graphical Internet group contains a Web browser. Package Management Tool The interface for this application is similar to the one used for individual package selection during installation. The standard packages can not be selected for removal unless the entire package group is removed. go to Applications (the main menu on the panel) => System Settings => Add/Remove Applications. Individual packages with a checkmark beside them are currently installed. click the Details link beside it. Packages are divided into package groups. email client. The main window shows a list of package groups. Package Management Tool During installation. . as long as the package group is selected. To view the individual packages list for a group. If the package group has a checkmark in the checkbox beside it. or type the command system-config-packages at shell prompt. a default set of software packages are installed.Chapter 16. The extra packages are optional packages that can be selected for installation or removal.
If there are package dependencies. The list of standard and extra packages is displayed. Figure 16-3.122 Chapter 16. they are automatically added to the list of packages to install. When it is finished. Clicking on the package name displays the disk space required to install the package at the bottom of the window. Package Management Tool 16. Information such as the number of packages to be installed and the amount of disk space required to install the packages.1. Installing Packages To install standard packages from a package group that is not currently installed. Figure 16-2. click the Details link beside it. as shown in Figure 16-2. click the Update button on the main window. Package Installation Summary Click Continue to start the installation process. To customize the packages to be installed within a group. check the checkbox beside that package group. is displayed in a summary window. an Update Complete message appears. . as well as any package dependencies. Click the Show Details button to view the complete list of packages to be installed. Individual Package Selection After selecting package groups and individual packages to install. You can also select individual packages from already installed package groups by clicking the Details link and checking any of the extra packages not already installed. Checking the checkbox beside the package name marks it for installation.
go to the directory that contains an RPM package (they usually end in .2.rpm). you can also use it to install packages. an Update Complete message appears. The Completed System Preparation window displays the number of packages to be installed and removed. uncheck the checkbox beside it. Package Management Tool 123 Tip If you use Nautilus to manage the files and directories on your computer. If other packages depend on the packages you selected to remove. To remove individual packages. When you are finished selecting packages to remove. The application computes the amount of freed disk space as well as the software package dependencies. click the Update button in the main window. Figure 16-4.Chapter 16. 16. and double-click on the RPM icon. click the Details button beside the package group and uncheck the individual packages. they are automatically added to the list of packages to be removed. Package Removal Summary Click Continue to start the removal process. Click the Show Details button to view the list of complete packages to be removed. Tip You can combine the installation and removal of packages by selecting package groups/packages to be installed/removed and then clicking Update. Removing Packages To remove all the packages installed within a package group. When it is finished. In Nautilus. .
Package Management Tool .124 Chapter 16.
Red Hat Network Red Hat Network is an Internet solution for managing one or more Red Hat Enterprise Linux systems. Your RHN Red Hat Network saves you time because you receive email when updated packages are released. By default.Chapter 17. Bug Fix Alerts. Bug Fix Alerts. Red Hat Network features include: • Errata Alerts — learn when Security Alerts.com/.redhat. and Enhancement Alerts (collectively known as Errata Alerts) can be downloaded directly from Red Hat using the Red Hat Update Agent standalone application or through the RHN website available at https://rhn. All Security Alerts. Figure 17-1. You do not have to learn how to use RPM or worry about resolving software package dependencies. Red Hat Network installs the packages as well. You do not have to search the Web for updated packages or security alerts. RHN does it all. and Enhancement Alerts are issued for all the systems in your network .
Relevant Errata • • • • • Automatic email notifications — Receive an email notification when an Errata Alert is issued for your system(s) Scheduled Errata Updates — Schedule delivery of Errata Updates Package installation — Schedule package installation on one or more systems with the click of a button Red Hat Update Agent — Use the Red Hat Update Agent to download the latest software packages for your system (with optional package installation) Red Hat Network website — Manage multiple systems. The first time the system is booted. go to: http://www. register it with Red Hat Network to receive Errata Updates. . a list of packages installed on the system is compiled so you are only notified about updates that are relevant to your system. execute the command up2date from a shell prompt. If you did not register then. For example. Alternately. To activate your product. Red Hat Network Figure 17-2. select Applications (the main menu on the panel) => System Tools => Red Hat Network on your desktop to start the registration process.126 Chapter 17.redhat. downloaded individual packages. The registration process gathers information about the system that is required to notify you of updates. and schedule actions such as Errata Updates through a secure Web browser connection from any computer Caution You must activate your Red Hat Enterprise Linux product before registered your system with Red Hat Network to make sure your system is entitled to the correct services. the Setup Agent prompts you to register.com/apps/activate/ After activating your product.
com/ For more detailed instructions.com/docs/manuals/RHNetwork/ Tip Red Hat Enterprise Linux includes the Red Hat Network Alert Notification Tool. .redhat. refer to the documentation available at: http://www. a convenient panel icon that displays visible alerts when there is an update for your Red Hat Enterprise Linux system. Registering with RHN After registering. Red Hat Network 127 Figure 17-3.Chapter 17.redhat. use one of the following methods to start receiving updates: • • • Select Applications (the main menu on the panel) => System Tools => Red Hat Network on your desktop Execute the command up2date from a shell prompt Use the RHN website at https://rhn.
128 Chapter 17. Red Hat Network .
.............. 195 26............................................. 153 20...................................... 211 27................................. 177 24..................... Controlling Access to Services .............................. Basic Firewall Configuration ................ 131 19........................................................................ 157 21............... Network Configuration............................................ Network File System (NFS).. Apache HTTP Secure Server Configuration .......... Table of Contents 18............ Dynamic Host Configuration Protocol (DHCP)........ 169 23.... share files and directories over the network........................... this part discusses topics related to networking such as how to allow remote logins......................................... 223 .................................. Apache HTTP Server Configuration.............................................. Network-Related Configuration After explaining how to configure the network........................................ and set up a Web server............................................................................................................................................................................................................................................................ 187 25.............IV........................................................................................ Authentication Configuration ............. OpenSSH........ 163 22................................................................. Samba.............................
or type the command system-config-network at a shell prompt (for example. the graphical version is displayed if X is running. If you type the command. go to the Main Menu Button (on the Panel) => System Settings => Network. . This is accomplished by having the operating system recognize an interface card (such as Ethernet. computers must have a network connection. Figure 18-1. refer to the Red Hat Enterprise Linux Reference Guide for information on their locations and contents. ISDN modem. To start the application. or token ring) and configuring the interface to connect to the network.Chapter 18. To use the command line version. otherwise. the text-based version is displayed. and manage the /etc/hosts file used to store additional hostnames and IP address combinations. The Network Administration Tool can be used to configure the following types of network interfaces: • • • • • • • Ethernet ISDN modem xDSL token ring CIPE wireless devices It can also be used to configure IPsec connections. execute the command system-config-network-cmd --help as root to view all of the options. Network Administration Tool If you prefer modifying the configuration files directly. To use the Network Administration Tool. in an XTerm or a GNOME terminal). Network Configuration To communicate with other computers. manage DNS settings. you must have root privileges.
In the Configure Network Settings window as shown in Figure 18-2. 6. Click Apply on the Create Ethernet Device page. Different networks are configured to use different network speeds. follow these steps: 1. make sure your NIC is compatible with the network to which you want to connect. perform the following steps: 1. Note The installation program detects supported Ethernet devices and prompts you to configure them. Click Forward to continue. 2. If you configured any Ethernet devices during the installation. 4. Configure the hostname and DNS settings. choose between DHCP and a static IP address. The Network Administration Tool also allows you to configure the resources for the NIC. . 18. a network cable (usually a CAT5 cable). 3. if this is the second Ethernet card. select Other Ethernet Card to add the hardware device. Network Configuration Tip Use the Red Hat Hardware Compatibility List (http://hardware. Add the physical hardware device to the hardware list. do not specify a hostname. 5. To add an Ethernet connection. Configure any hosts that cannot be looked up through DNS. if it does not already exist. Click the Devices tab.132 Chapter 18. 4. If you have already added the network interface card to the hardware list. select eth0 as the device name. Select the manufacturer and model of the Ethernet card. Add a network device associated with the physical hardware device. Click the New button on the toolbar. Select the device name. 18. Click Forward to continue. you need a network interface card (NIC). 2. If the device receives a different IP address each time the network is started. Select Ethernet connection from the Device Type list. If this is the system's first Ethernet card.com/hcl/) to determine if Red Hat Enterprise Linux supports your hardware device. Establishing an Ethernet Connection To establish an Ethernet connection.1. If you selected Other Ethernet Card. Otherwise. select eth1 (and so on). 7.2. they are displayed in the hardware list on the Hardware tab. 3. the Select Ethernet Adapter window appears.redhat. and a network to connect to. This chapter discusses each of these steps for each type of network connection. Overview To configure a network connection with the Network Administration Tool. select it from the Ethernet card list. and click Forward.
you can configure an eth1 device and an eth1:1 device. Ethernet Device Be sure to select File => Save to save the changes. For example. If the system is configured to activate the device when the computer starts (the default).Chapter 18. For details. After adding the Ethernet device. refer to Section 18. select it from the device list. modify the Activate device when computer starts value. and save the changes. If you associate more than one device with an Ethernet card. this step does not have to be performed again. When the device is added. Network Configuration 133 Figure 18-2. To change this setting. . the subsequent devices are device aliases. you can edit its configuration by selecting the device from the device list and clicking Edit. A device alias allows you to setup multiple virtual devices for one physical device. thus giving the one physical device more than one IP address. Figure 18-3.11 Device Aliases. and click the Activate button. To activate the device. it appears in the device list as shown in Figure 18-3. it is configured to start at boot time by default. select to edit the device. Ethernet Settings After configuring the Ethernet device. For example. as seen by its Inactive status. when the device is added. it is not activated immediately.
If your Internet Service Provider (ISP) is in the pre-configured list. ISDN Settings 5. it is configured not to start at boot time by default. Network Configuration 18. as seen by its Inactive status. and more can be changed. If you do not know the values. ISDN connections are popular in Europe. select the Encapsulation Mode and whether to obtain an IP address automatically or to set one statically. When the device is added. select it from the device list. you can edit its configuration by selecting the device from the device list and clicking Edit. For example. PPP options. Click Forward to continue. Be sure to select File => Save to save the changes. this step does not have to be performed again. After configuring the ISDN device. If the system is configured to activate the device when the computer starts (the default). Edit its configuration to modify this setting. click Apply. Click the New button on the toolbar.3. Click Forward when finished. Compression. contact your ISP. password. . In the IP Settings window. 6. Then configure the resources and D channel protocol for the adapter. enter the required information about your ISP account. Click the Devices tab. and click the Activate button. To add an ISDN connection. 7. 2. After adding the ISDN device. 4. and click Forward. Click Forward. it is not activated immediately. when the device is added. select it. To activate the device. Select ISDN connection from the Device Type list.134 Chapter 18. Select the ISDN adapter from the pulldown menu. Otherwise. login name. Establishing an ISDN Connection An ISDN connection is an Internet connection established with a ISDN modem card through a special phone line installed by the phone company. On the Create Dialup Connection page. it appears in the device list as a device with type ISDN as shown in Figure 18-5. 3. Figure 18-4. follow these steps: 1.
If there is a modem already configured in the hardware list (on the Hardware tab). Figure 18-6. a message is displayed to warn you that the settings shown are not values found from the probe. the Network Administration Tool assumes you want to use it to establish a modem connection.Chapter 18. Select Modem connection from the Device Type list. Click the New button on the toolbar. Modem Settings . and click Forward. An Internet Service Provider (ISP) account (also called a dial-up account) is required. Network Configuration 135 Figure 18-5. 4. If a modem is not found. This probe might take a while. If there are no modems already configured. To add a modem connection. Establishing a Modem Connection A modem can be used to configure an Internet connection over an active phone line. 2.4. After probing. it tries to detect any modems in the system. the window in Figure 18-6 appears. 5. 3. ISDN Device 18. Click the Devices tab. follow these steps: 1.
flow control. enter the required information about your ISP account. 9. it appears in the device list with the type Modem as shown in Figure 18-7. 8.136 Chapter 18. contact your ISP. and click the Activate button. Compression. If you do not have touch tone dialing. The Network Administration Tool uses the term xDSL to mean all types of DSL connections. select whether to obtain an IP address automatically or whether to set on statically. click Apply. If you do not know these values. follow these steps: . and modem volume. Click Forward when finished. When the device is added. Modem Device Be sure to select File => Save to save the changes. login name. as seen by its Inactive status. On the IP Settings page. uncheck the corresponding checkbox.5. There are different types of DSL such as ADSL. when the device is added. After adding the modem device. If your ISP is in the pre-configured list. If the system is configured to activate the device when the computer starts (the default). 18. Click Forward. accept the defaults if the modem was probed successfully. If you are required to use DHCP. refer to Section 18. password. Edit its configuration to modify this setting. select it. Some DSL providers require you to configure a PPPoE (Point-to-Point Protocol over Ethernet) connection with an Ethernet card.2 Establishing an Ethernet Connection to configure your Ethernet card. Figure 18-7. If you do not know these values. and more can also be changed. 7. this step does not have to be performed again. PPP options. Click Forward. Some DSL providers require that the system is configured to obtain an IP address through DHCP with an Ethernet card. After configuring the modem device. and SDSL. it is not activated immediately. IDSL. To activate the device. you can edit its configuration by selecting the device from the device list and clicking Edit. Configure the modem device. If you are required to use PPPoE. Otherwise. Establishing an xDSL Connection DSL stands for Digital Subscriber Lines. Ask your DSL provider which method to use. it is configured not to start at boot time by default. On the Create Dialup Connection page. For example. Network Configuration 6. baud rate. select it from the device list.
Click Forward to continue. If the Select Ethernet Adapter window appears. Note The installation program detects supported Ethernet devices and prompts you to configure them. 2. click the T-Online Account Setup button and enter the required information. they are displayed in the hardware list on the Hardware tab. If this is the system's first Ethernet card. and Password.Chapter 18. On the Create DSL Connection page. Figure 18-8. The Network Administration Tool also allows you to configure the resources for the NIC. select eth0 as the device name. 3. instead of entering a Login Name and Password in the default window. Click the New button. Click the Devices tab. the Select Ethernet Adapter window appears. 6. select the Ethernet Device from the pulldown menu from the page shown in Figure 18-8. Enter the Provider Name. if this is the second Ethernet card. it appears in the device list as shown in Figure 18-7. 137 4. click Apply. If you configured any Ethernet devices during the installation. . and click Forward. Select the device name. select the manufacturer and model of the Ethernet card. select eth1 (and so on). If your Ethernet card is in the hardware list. 7. Network Configuration 1. xDSL Settings 5. Otherwise. Login Name. Select xDSL connection from the Device Type list. If you have a T-Online account. After configuring the DSL connection. Click Forward to continue.
or a special network packet. Select the manufacturer and model of the adapter. Establishing a Token Ring Connection A token ring network is a network in which all the computers are connected in a circular pattern. this step does not have to be performed again. To add a token ring connection. If you have already added the token ring card to the hardware list.net/. Tip For more information on using token ring under Linux. select it from the Tokenring card list. refer to the Linux Token Ring Project website available at http://www. Click the New button on the toolbar. if this is the second token ring card. you can edit its configuration by selecting the device from the device list and clicking Edit. as seen by its Inactive status. the Select Token Ring Adapter window as shown in Figure 18-10 appears.138 Chapter 18. When the device is added. xDSL Device Be sure to select File => Save to save the changes. If you selected Other Tokenring Card. Select the device name. and click the Activate button. Otherwise.linuxtr. 4.6. 18. For example. If this is the system's first token ring card. follow these steps: 1. select tr0. travels around the token ring and allows computers to send information to each other. Network Configuration Figure 18-9. A token. it is configured not to start at boot time by default. After adding the xDSL connection. 3. Click the Devices tab. 5. If the system is configured to activate the device when the computer starts (the default). Click Forward to continue. select Other Tokenring Card to add the hardware device. The Network Administration Tool also allows the user to configure the resources for the adapter. select tr1 (and so on). select it from the device list. 2. . Select Token Ring connection from the Device Type list and click Forward. Edit its configuration to modify this setting. it is not activated immediately. when the device is added. To activate the device.
it appears in the device list as shown in Figure 18-11. Click Forward to continue. you can edit its configuration by selecting the device from the device list and clicking Edit. it is not activated immediately. Figure 18-11. choose between DHCP and static IP address. After configuring the token ring device. 7. On the Configure Network Settings page. If the system is configured to activate the device when the computer starts (the default). To activate the device. and click the Activate button. If the device receives a dynamic IP address each time the network is started. Token Ring Device Be sure to select File => Save to save the changes. After adding the device.Chapter 18. . For example. you can configure whether the device is started at boot time. Click Apply on the Create Tokenring Device page. Token Ring Settings 6. this step does not have to be performed again. select it from the device list. You may specify a hostname for the device. do not specify a hostname. When the device is added. as seen by its Inactive status. Network Configuration 139 Figure 18-10.
. On the Configure Wireless Connection page as shown in Figure 18-12. If you selected Other Wireless Card. Click Forward to continue. they are displayed in the hardware list on the Hardware tab. On the Configure Network Settings page. 2. do not specify a hostname. The Network Administration Tool also allows the user to configure the resources for the wireless network interface card. 6. If this is the first Ethernet card for the system. Network Configuration 18. After configuring the wireless device. select eth1 (and so on). 5. Otherwise. Select Wireless connection from the Device Type list and click Forward. Wireless Settings 7. Figure 18-12. it appears in the device list as shown in Figure 18-13. select eth0. 4.7. if this is the second Ethernet card for the system. select Other Wireless Card to add the hardware device. select it from the Wireless card list. The configuration is similar to the Ethernet configuration except that it allows you to configure settings such as the SSID and key for the wireless device. Click the New button on the toolbar. Establishing a Wireless Connection Wireless Ethernet devices are becoming increasingly popular. 3. If the device receives a dynamic IP address each time the network is started. follow these steps: 1.140 Chapter 18. To add a wireless Ethernet connection. configure the settings for the wireless device. Select the manufacturer and model of the Ethernet card and the device. Click the Devices tab. If you configured them during the installation. the Select Ethernet Adapter window appears. choose between DHCP and static IP address. Click Apply on the Create Wireless Device page. Note The installation program usually detects supported wireless Ethernet devices and prompts you to configure them. If you have already added the wireless network interface card to the hardware list. You may specify a hostname for the device. Click Forward to continue. 8.
If the hostname is retrieved dynamically from DHCP or PPPoE (or retrieved from the ISP). and click the Activate button. Network Configuration 141 Figure 18-13. or tertiary DNS servers. 18. you can edit its configuration by selecting the device from the device list and clicking Edit. you can configure the device to activate at boot time. do not change it. When the device is added.Chapter 18. it is not activated immediately. as seen by its Inactive status. After adding the wireless device. domain.8. Managing DNS Settings The DNS tab allows you to configure the system's hostname. Figure 18-14. If the system is configured to activate the device when the computer starts (the default). do not add primary. select it from the device list. Name servers are used to look up other hosts on the network. this step does not have to be performed again. secondary. and search domain. name servers. To activate the device. DNS Configuration . For example. Wireless Device Be sure to select File => Save to save the changes. If the DNS server names are retrieved from DHCP or PPPoE (or retrieved from the ISP).
it refers to the /etc/hosts file before using the name servers (if you are using the default Red Hat Enterprise Linux configuration). it configures the name servers to use when resolving IP addresses to hostnames and vice versa. or remove hosts from the /etc/hosts file. go to the Hosts tab. Instead. and click OK. Figure 18-15. 18. Managing Hosts The Hosts tab allows you to add. The network or network services do not need to be restarted since the current version of the file is referred to each time an address is resolved. Hosts Configuration .142 Chapter 18. Warning Do not remove the localhost entry. click the New button on the toolbar. Network Configuration Note The name servers section does not configure the system to be a name server. If your network contains computers whose IP addresses are not listed in DNS. To add an entry to the /etc/hosts file. When your system tries to resolve a hostname to an IP address or tries to determine the hostname for an IP address. it is recommended that you add them to the /etc/hosts file. some programs need to connect to the system via the localhost loopback interface. Even if the system does not have a network connection or have a network connection running constantly. edit. the name servers are not used. If the IP address is listed in the /etc/hosts file. Select File => Save or press [Ctrl]-[S] to save the changes to the /etc/hosts file.9. This file contains IP addresses and their corresponding hostnames. provide the requested information.
Network Configuration 143 Tip configures the system to resolve hostnames and IP addresses using the name servers first. there is a column of checkboxes labeled Profile. Changing the line to order bind. there is one profile called Common. Only the checked devices are included for the currently selected profile. By default. If you use the New button. Logical network devices are different from device aliases. For example. edit the /etc/host. bind specifies that /etc/hosts takes precedence over the name servers. Device aliases are also associated with the same physical hardware device. a network alias is created. . which is incorrect. To change lookup order. For example. Logical network devices associated with the same physical device must exist in different profiles and cannot be activated simultaneously. For example. For example. the system then looks for the IP address in the /etc/hosts file. If the IP address cannot be resolved through the name servers. you can create logical network devices with different nicknames and different configuration options. select it from the list and click Edit. if you have one Ethernet card in your system (eth0).Chapter 18. the nickname can be changed to a more descriptive name. You are now modifying the new profile as indicated by the status bar at the bottom of the main window. you can use the Network Administration Tool to switch back and forth between them. A configuration set can include logical devices as well as hosts and DNS settings. if you create a logical device named eth0_office in a profile called Office and want to activate the logical device if the profile is selected. The line order hosts. Working with Profiles Multiple logical network devices can be created for each physical hardware device. Figure 18-16 shows a profile called Office with the logical device eth0_office. but device aliases associated with the same physical hardware can be activated at the same time. Refer to Section 18. and enter a unique name for the profile. Click on an existing device already in the list and click the Copy button to copy the existing device to a logical network device. you can check or uncheck devices. all to be specifically associated with eth0. uncheck the eth0 device and check the eth0_office device. In the list of devices. so that it can be recognized more easily. To change the properties of the logical device. It is configured to activate the first Ethernet card using DHCP. Profiles can be used to create multiple configuration sets for different networks. hosts 18. select Profile => New from the pull-down menu. For each profile.10. After configuring the profiles.conf file. To create a new profile.11 Device Aliases for details about creating device aliases. such as eth0_office.
For example.9-5. To activate a profile at boot time.img modify it to the following (where <profilename> is the name of the profile to be activated at boot time): title Red Hat Enterprise Linux (2. Office Profile Notice that the Home profile as shown in Figure 18-17 activates the eth0_home logical device.9-5.6.9-5.EL) root (hd0.EL ro root=/dev/VolGroup00/LogVol00 rhgb quiet initrd /initrd-2.9-5.0) kernel /vmlinuz-2.EL. Home Profile You can also configure eth0 to activate in the Office profile only and to activate a PPP (modem) device in the Home profile only.6. Another example is to have the Common profile activate eth0 and an Away profile activate a PPP device for use while traveling. if the system uses GRUB as the boot loader and /boot/grub/grub.6.EL) .conf contains: title Red Hat Enterprise Linux (2. Figure 18-17. which is associated with eth0. modify the boot loader configuration file to include the netprofile=<profilename> option.6. Network Configuration Figure 18-16.144 Chapter 18.
0) kernel /vmlinuz-2. the one just created is the alias. After configuring the Ethernet device. but the system only has one network card. Select the Ethernet card to configure with an alias. eth0:1). Notice the eth0:1 device — the first alias for eth0.Chapter 18. Warning If you are configuring an Ethernet device to have an alias. execute the following command to enable a profile (replace <profilename> with the name of the profile): system-config-network-cmd --profile <profilename> --activate 18. but they can be activated at the same time to have different IP addresses. You must configure the IP addresses manually.6. and so on.6. Alternatively. Network Configuration root (hd0. neither the device nor the alias can be configured to use DHCP. The second alias for eth0 would have the device name eth0:2. set the static IP address for the alias. The activate profile section only appears in the Network Device Control interface if more than the default Common interface exists.EL. select it from the list and click the Edit button. such as eth0:1. and click Apply to create it.9-5. .11. Since a device already exists for the Ethernet card. go to the Devices tab and click New. They are commonly represented as the device name followed by a colon and a number (for example.9-5. To modify the settings for the device alias. such as eth0. They are useful if you want to have multiple IP address for a system.EL ro root=/dev/VolGroup00/LogVol00 \ netprofile=<profilename> \ rhgb quiet initrd /initrd-2. go to Main Menu (on the Panel) => System Tools => Network Device Control (or type the command system-control-network) to select a profile and activate it. Figure 18-18 shows an example of one alias for the eth0 device.img 145 To switch profiles after the system has booted. to use a static IP address (DHCP does not work with aliases). such as whether to activate it at boot time and the alias number. Device Aliases Device aliases are virtual devices associated with the same physical hardware.
100. The output should show the device and the device alias with different IP addresses: eth0 Link encap:Ethernet HWaddr 00:A0:CC:60:B7:G4 inet addr:192. use the command /sbin/ifconfig. It is a Virtual Private Network (VPN) solution in which an encrypted connection is established between two systems (host-to-host) or two networks (networkto-network).5 Bcast:192. .0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:5998 errors:0 dropped:0 overruns:0 frame:0 TX packets:5998 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1627579 (1.100.8 Mb) Interrupt:10 Base address:0x9000 Link encap:Ethernet HWaddr 00:A0:CC:60:B7:G4 inet addr:18.104.22.168.42 Bcast:192. Network Configuration Figure 18-18.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:10 Base address:0x9000 Link encap:Local Loopback inet addr:127. Establishing an IPsec Connection IPsec stands for Internet Protocol Security.5 Mb) eth0:1 lo 18.5 Mb) TX bytes:178108895 (188.8.131.52.255 Mask:255.168.146 Chapter 18. If you have configured multiple profiles. select which profiles in which to include it.255.0.5 Mb) TX bytes:1627579 (184.108.40.206.0. To verify that the alias has been activated.168.168.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:161930 errors:1 dropped:0 overruns:0 frame:0 TX packets:244570 errors:0 dropped:0 overruns:0 carrier:0 collisions:475 txqueuelen:100 RX bytes:55075551 (52. Network Device Alias Example Select the alias and click the Activate button to activate the alias.255 Mask:255.1 Mask:255.
Click Forward to continue. Select the type of encryption to use: manual or automatic. 3. Otherwise. From the IPsec tab. 9. 6. Select File => Save to save the configuration. Repeat for the other host. 18.ipsec-howto. If you do not know the IP address of the other system. specify the encryption key to use or click Generate to create one. it appears in the IPsec list as shown in Figure 18-19.1.Chapter 18. select New. and click Apply. use the following steps for each host: 1. Click Forward to start configuring a host-to-host IPsec connection. The IP address is the number following the inet addr: label. Provide a one word nickname such as ipsec0 for the connection. any network traffic between the two hosts is encrypted. 5. If manual encryption was selected in step 6. Click Forward. If automatic is selected. Specify an authentication key or click Generate to generate one. Select Host to Host encryption as the connection type. 7. If manual is selected. Host-to-Host Connection A host-to-host IPsec connection is an encrypted connection between two systems both running IPsec with the same authentication key. It can be any combination of numbers and letters. Select the IPsec connection from the list and click the Activate button. the device name is eth0. 4. the racoon daemon is used to manage the encryption key. an encryption key must be provided later in the process. Click Forward to continue. After configuring the IPsec connection. With the IPsec connection active. the other host. If racoon is used.12.org/ for more information about IPsec. 12. Network Configuration 147 Tip Go to http://www. and select whether the connection should be automatically activated when the computer starts. To configure a host-to-host IPsec connection. IPsec does not work. 10. If only one Ethernet card exists in the system. 8. 11. Specify the IP address of the other host. where <device> is the Ethernet device used to connect to . run the command /sbin/ifconfig <device> on the other system. Verify the information on the IPsec — Summary page. It is extremely important that the same keys from step 8 be used on the other hosts. 2. Click Forward to continue. Start the Network Administration Tool. Click Forward. the ipsec-tools package must be installed.
through the Internet. to ipsec0.conf is created as well.12. Figure 18-20.txt are created in /etc/racoon/. and racoon. Traffic only travels through it if it is intended for the other IPsec router with which it has an encrypted connection.168. Refer to Section 18. /etc/racoon/racoon. The IPsec router and the . Network Configuration Figure 18-19. the packets go through gateway0.168. to ipsec1.168. and an Intranet firewall between each IPsec router and subnet gateway. If automatic encryption is selected. When the interface is activated. IPsec Connection Two files are created in the /etc/sysconfig/network-scripts/ directory — ifcfg-<nickname> and keys-<nickname>. For example. to gateway1.conf. Network-to-Network IPsec Alternate network configurations options include a firewall between each IP router and the Internet.3 Testing the IPsec Connection to determine if the IPsec connection has been successfully established. through which the network traffic for the private subnets is routed.148 Chapter 18. <remote-ip>.0/24 subnet.12.conf and psk. if the 192. and to the 192. 18.0/24 private network.2. The IPsec routers must have publicly addressable IP addresses as well as another Ethernet device connected to its private network. one for each network. as shown in Figure 18-20.2.conf is modified to include <remote-ip>.0/24 private network sends network traffic to the 192.2. Network-to-Network (VPN) Connection A network-to-network IPsec connection uses two IPsec routers.
3. Local Network Gateway — The gateway for the private subnet. 2. Click Forward to continue. 6. 4. • • • . one with a public IP address that acts as the IPsec router and one with a private IP address that acts as the gateway for the private subnet. enter the following information: • Remote IP Address — The publicly addressable IP address of the IPsec router for the other private network.168. enter 192. Each IPsec router can use the gateway for its private network or a public gateway to send the packets to the other IPsec router. 7. To configure a network-to-network IPsec connection. select New. Select the type of encryption to use: manual or automatic. and vice versa. Local Network Information 8. Select Network to Network encryption (VPN).0 if configuring ipsec0. Provide a one word nickname.Chapter 18. and enter 192. On the Remote Network page. In our example. Network Configuration 149 gateway for the subnet can be one system with two Ethernet devices. In our example. Remote Subnet Mask — The subnet mask of the remote IP address. From the IPsec tab.1.168. Click Forward. enter the following information: • • • Local Network Address — The IP address of the device on the IPsec router connected to the private network. for ipsec0. and click Forward. Start the Network Administration Tool. 5. an encryption key must be provided later in the process. On the Local Network page. enter the publicly addressable IP address of ipsec1. for the connection and select whether the connection should be automatically activated when the computer starts. If manual is selected. Figure 18-21.2. Remote Network Gateway — The IP address of the gateway for the remote network address. such as ipsec0. Click Forward to start configuring a network-to-network IPsec connection. use the following steps: 1. the ipsec-tools package must be installed.0 if configuring ipsec1. If automatic is selected. Remote Network Address — The network address of the private subnet behind the other IPsec router. If racoon is used. Local Subnet Mask — The subnet mask of the local network IP address. Click Forward to continue. the racoon daemon is used to manage the encryption key.
3.com: \ AH(spi=0x0aaa749f. enable IP forwarding: a.150 • Chapter 18.conf and set net. Select File => Save to save the configuration.12. It can be any combination of numbers and letters. The packet should include an AH header and should be shown as ESP packets. as displayed in the previous example.3 Testing the IPsec Connection to determine if the IPsec connection has been successfully established. . For example. and click Apply. Testing the IPsec Connection Use the tcpdump utility to view the network packets being transfered between the hosts (or networks) and verify that they are encrypted via IPsec. manually kill the process by pressing [Ctrl]-[C]. and click the Activate button.com > ijin. A few seconds after starting tcpdump. b. An advanced IPsec test would require four systems. 12. issue the following command as root: # tcpdump 17:13:20. Execute the following command to enable the change: /sbin/sysctl -p /etc/sysctl. specify the encryption key to use or click Generate to create one.ip_forward to 1.ipv4. You should see similar ESP packets signifying a working IPsec connection. Specify an authentication key or click Generate to generate one.example.seq=0x335): ESP(spi=0x0ec0441e. Figure 18-22. Remote Network Information 9. 18. which would fulfill a full multi-homed IPsec network. As root at a shell prompt.12. Network Configuration If manual encryption was selected in step 6. Refer to Section 18. 10. Edit /etc/sysctl.seq=0x335) (DF) The tcpdump command outputs live network traffic.example. Select the IPsec connection from the list.conf The network script to activate the IPsec connection automatically creates network routes to send packets through the IPsec router if necessary. Click Forward to continue. but is not discussed here. 11.617872 pinky. ESP means it is encrypted. Verify the information on the IPsec — Summary page.
the system's network configuration to the file /tmp/network-config. To start the connection. execute the following command as root on each host for host-to-host IPsec or each IPsec router for network-to-network IPsec (replace <ipsec-nick> with the one word nickname configured earlier. execute the following command as root: system-config-network-cmd -e > /tmp/network-config To restore.13. such as ipsec0): /sbin/ifup <ipsec-nick> To stop the connection. Network Configuration 151 18. or to copy the configuration to a different Red Hat Enterprise Linux system. such as ipsec0): /sbin/ifdown <ipsec-nick> 18. start and stop it as root via the command line.Chapter 18. Starting and Stopping the Connection If the IPsec connection was not configured to activate on boot. This feature can be used as part of an automated backup script. execute the following command as root on each host for host-to-host IPsec or each IPsec router for network-to-network IPsec (replace <ipsec-nick> with the one word nickname configured earlier. execute the following command as root: system-config-network-cmd -i -c -f /tmp/network-config The -i option means to import the data. . To save. or export. the network configuration from the file created from the previous command.4.12. or import. and the -f option specifies that the file to import is as follows. Saving and Restoring the Network Configuration The command line version of Network Administration Tool can be used to save the system's network configuration to a file. the -c option means to clear the existing configuration prior of importing. This file can then be used to restore the network settings to a Red Hat Enterprise Linux system. to save the configuration before upgrading or reinstalling.
152 Chapter 18. Network Configuration .
Chapter 19. Basic Firewall Configuration Just as a firewall in a building attempts to prevent a fire from spreading. you were given the option to enable a basic firewall as well as to allow specific devices. It is recommended that you configure a firewall for any Red Hat Enterprise Linux system with an Internet connection. Security Level Configuration Tool During the Firewall Configuration screen of the Red Hat Enterprise Linux installation. you can change this preference by using the Security Level Configuration Tool. incoming services. To start the application.1. and ports. After installation. a computer firewall attempts to prevent computer viruses from spreading to your computer and to prevent unauthorized users from accessing your computer. . 19. select Main Menu Button (on the Panel) => System Settings => Security Level or type the command system-config-securitylevel from a shell prompt (for example. in an XTerm or a GNOME terminal). If the system needs more complex rules. A properly configured firewall can greatly increase the security of your system. A firewall exists between your computer and the network. Figure 19-1. It determines which services on your computer remote users on the network can access. Security Level Configuration Tool Note The Security Level Configuration Tool only configures a basic firewall. refer to the Red Hat Enterprise Linux Reference Guide for details on configuring specific iptables rules.
enable this option. If access to services running on this machine is needed. WWW (HTTP) The HTTP protocol is used by Apache (and by other Web servers) to serve webpages. the SSL version of HTTP.154 Chapter 19.1. Basic Firewall Configuration 19. enable this option. such as DNS replies or DHCP requests. . Warning If you have a firewall configured or any customized firewall rules in the /etc/sysconfig/iptables file. If you plan on making your Web server publicly available. You must have the httpd package installed to serve webpages. Mail (SMTP) To allow incoming mail delivery through your firewall so that remote hosts can connect directly to your machine to deliver mail. Note that an improperly configured SMTP server can allow remote machines to use your server to send spam. you must have the telnet-server package installed. this is the safest choice. Security checking is the disabling of access to certain services. Enabling and Disabling the Firewall Select one of the following options: • Disable firewall — Disabling the firewall provides complete access to your system and does no security checking.1. The openssh-server package must be installed to access your machine remotely using SSH tools. the file is deleted by selecting Disable firewall and clicking OK to save the changes. This should only be selected if you are running on a trusted network (not the Internet) or plan to do more firewall configuration later. You do not need to enable this if you collect your mail from your ISP's server using POP3 or IMAP.1. Allowing incoming Telnet access is not recommended. Telnet communications are unencrypted and provide no security from network snooping. If you plan on making your FTP server publicly available. This option is not required for viewing pages locally or for developing webpages.2. enable this option. Telnet Telnet is a protocol for logging into remote machines. 19. or if you use a tool such as fetchmail. FTP The FTP protocol is used to transfer files between machines on a network. enable this option. To allow remote access to the machine via ssh. The vsftpd package must be installed for this option to be useful. To allow inbound Telnet access. • Enable firewall — This option configures the system to reject incoming connections that are not in response to outbound requests. Enabling WWW (HTTP) will not open a port for HTTPS. SSH Secure Shell (SSH) is a suite of tools for logging into and executing commands on a remote machine. but do not plan to run a server. you can choose to allow specific services through the firewall. If you are connecting your system to the Internet. Trusted Services Enabling options in the Trusted services list allows the specified service to pass through the firewall.
a Trusted device. the /etc/sysconfig/iptables file is removed and the iptables service is stopped immediately. For example.3. it becomes excluded from the firewall rules. 19.1. If Disable firewall was selected. The iptables service is also started so that the firewall is activated immediately after saving the selected options. You may have noticed a sit0 device in the Trusted devices section.2 Activating the iptables Service for details. Other Ports The Security Level Configuration Tool includes the Other ports section for adding custom IP ports to become trusted by iptables. if you are running a local network. which encapsulates IPv6 traffic into IPv4 traffic.194:tcp. Trusted Devices Selecting any of the Trusted devices allows access to your system for all traffic from that device. the iptables service is not configured to start automatically at boot time refer to Section 19. If Enable firewall was selected. the options selected are translated to iptables commands and written to the /etc/sysconfig/iptables file. To manually start the service. but are connected to the Internet via a PPP dialup. and Internet printing protocol (IPP) to be allowed to pass through the firewall.2. leave it unchecked. you can check eth0 and any traffic coming from your local network is allowed.Chapter 19. use the command: /sbin/service iptables restart To ensure that it is started when the system is booted. and then is tunneled. Even though the firewall is activated immediately. 19.631:tcp 19.4. the following would be inserted in the Other ports section: 2049:tcp.5. This device stands for simple internet transition. issue the command: /sbin/chkconfig --level 345 iptables on . Saving the Settings Click OK to save the changes and enable or disable the firewall. Important It is not recommended that you make any device that is connected to public networks.1. to allow NFS. IRC.1. but the ppp0 interface is still firewalled. Selecting eth0 as trusted means all traffic over the Ethernet is allowed. For basic firewall rules. such as the Internet. Basic Firewall Configuration 155 19. The options selected are also written to the /etc/sysconfig/system-config-securitylevel file so that the settings can be restored the next time the application is started. To restrict traffic on an interface. this device can be ignored and left as an untrusted device. Do not edit this file by hand. For example. Activating the iptables Service The firewall rules are only active if the iptables service is running.
To make sure the ipchains service is disabled and configured not to start at boot time. Basic Firewall Configuration The ipchains service is not included in Red Hat Enterprise Linux. the ipchains service should not be activated along with the iptables service.156 Chapter 19. However. if ipchains is installed (for example. execute the following two commands: /sbin/service ipchains stop /sbin/chkconfig --level 345 ipchains off The Services Configuration Tool can be used to enable or disable the iptables and ipchains services. . an upgrade was performed and the system had ipchains previously installed).
httpd if you are running a Web server). stopped. and restarted.d. Refer to the Red Hat Enterprise Linux Reference Guide and the Red Hat Enterprise Linux Security Guide for more information about iptables. refer to the iptables chapter in the Red Hat Enterprise Linux Reference Guide. try the Security Level Configuration Tool (system-config-securitylevel).d. if you need a customized solution which provides certain hosts access to certain services. if you are looking for a utility to set general access rules for your home machine. 4.d/init. if you do not need to provide a service. There are several different methods for managing access to system services. Runlevels Before you can configure access to services. the benefit of using iptables is flexibility.d by hand or editing the xinetd configuration files in /etc/xinetd. displays whether each service is started at boot time (for runlevels 3. Setting up iptables can be complicated and is best tackled by experienced Linux system administrators. ntsysv — a text-based application that allows you to configure which services are started at boot time for each runlevel. and your level of Linux expertise.d hierarchy (also known as SysV services) can be configured to start or stop using three different applications: • Services Configuration Tool — a graphical application that displays a description of each service. 20. Non-xinetd services can not be started.d/rc<x>. and 5). Controlling Access to Services Maintaining security on your system is extremely important. and allows services to be started. — a command line utility that allows you to turn services on and off for the different runlevels. Alternatively. please realize that iptables may not be the best solution for you. your system's configuration. However. stopped. The easiest way to deny access to a service is to turn it off. Your system may need to provide open access to particular services (for example. where <x> is the number of the runlevel. which allows you to select the security level for your system. and one approach for this task is to manage access to system services carefully. Refer to Chapter 19 Basic Firewall Configuration for more information. that is defined by the services listed in the directory /etc/rc. and/or if you are new to Linux. The following runlevels exist: • 0 — Halt . you should turn it off to minimize your exposure to possible bug exploits.1. • • chkconfig You may find that these tools are easier to use than the alternatives — editing the numerous symbolic links located in the directories below /etc/rc. Decide which method of management to use based on the service. or mode. If you are a new Linux user. similar to the Firewall Configuration screen in the installation program. Non-xinetd services can not be started. If you need more specific firewall rules. stopped. iptables can provide it for you. or restarted using this program. For example. you must understand Linux runlevels. A runlevel is a state. On the other hand. or restarted using this utility. Both the services managed by xinetd and the services in the /etc/rc.Chapter 20. Another way to manage access to system services is by using iptables to configure an IP firewall.
conf. The xinetd daemon conserves system resources. You must be root to use this command. provides access control and logging. it continues to boot the runlevel as specified in /etc/inittab. 20. You can edit any of the xinetd configuration files or change its enabled status using the Services Configuration Tool. to provide access to a service at certain times. ntsysv.allow contains a list of rules that allow clients to access the network services controlled by xinetd. The telinit command does not change the /etc/inittab file. As the names imply. which is a secure replacement for inetd. To enable or disable an xinetd service. you are operating in runlevel 3.deny file. xinetd can be used to provide access only to particular hosts. to deny access to particular hosts. If you use a graphical login screen. and more xinetd runs constantly and listens on all ports for the services it manages. The default runlevel can be changed by modifying the /etc/inittab file. For a list of network services controlled by xinetd. To change the runlevel immediately. and hosts. The hosts. If the disable attribute is set to no. If the disable attribute is set to yes. .allow file takes precedence over the hosts.d directory. Any network services managed by xinetd (as well as any program with built-in support for libwrap) can use TCP wrappers to manage access. xinetd can use the /etc/hosts. use xinetd. it only changes the runlevel currently running. Controlling Access to Services 1 — Single-user mode 2 — Not used (user-definable) 3 — Full multi-user mode 4 — Not used (user-definable) 5 — Full multi-user mode (with an X-based login screen) 6 — Reboot If you use a text login screen. xinetd starts up the appropriate server for that service.158 • • • • • • Chapter 20.2. the service is enabled.d. xinetd To control access to Internet services.d directory. the service is disabled.2. you are operating in runlevel 5. but the file only contains a few defaults and an instruction to include the /etc/xinetd.deny files to configure access to system services. Refer to the Red Hat Enterprise Linux Reference Guide and hosts_access in section 5 of the man pages (man 5 hosts_access) for details. The configuration file for xinetd is /etc/xinetd. When a connection request arrives for one of its managed services. edit its configuration file in the /etc/xinetd. 20. TCP Wrappers Many UNIX system administrators are accustomed to using TCP wrappers to manage access to certain network services.d directory with the command ls /etc/xinetd.allow and /etc/hosts. which contains a line near the top of the file similar to the following: id:5:initdefault: Change the number in this line to the desired runlevel. hosts. to limit the rate of incoming connections and/or the load created by connections. and can be used to start special-purpose servers. use the command telinit followed by the runlevel number.1. Permissions to grant or deny access can be based on individual IP address (or hostnames) or on a pattern of clients. review the contents of the /etc/xinetd. or chkconfig. The change does not take effect until you reboot the system. When the system is rebooted.deny contains rules to deny access.
To start the Services Configuration Tool from the desktop.Chapter 20. Refer to Section 20. you must select File => Save Changes from the pulldown menu to restart xinetd and immediately enable/disable the xinetd service that you changed.1 Runlevels for a description of runlevels.d/init. Services Configuration Tool The Services Configuration Tool is a graphical application developed by Red Hat to configure which SysV services in the /etc/rc. go to the Main Menu Button (on the Panel) => System Settings => Server Settings => Services or type the command system-config-services at a shell prompt (for example. select Edit Runlevel from the pulldown menu and select runlevel 3. stop. the status window shows whether the service is currently running. 4. or restart a service immediately. in an XTerm or a GNOME terminal). To edit a different runlevel. If you enable/disable an xinetd service by checking or unchecking the checkbox next to the service name. To start.d directory are started at boot time (for runlevels 3. the action buttons are disabled because they can not be started or stopped individually. If the service is controlled by xinetd. It also allows you to start. You can enable/disable multiple xinetd services at a time and save the changes when you are finished. Click on the name of the service from the list on the left-hand side of the application to display a brief description of that service as well as the status of the service.3.d directory as well as the services controlled by xinetd. and restart SysV services as well as restart xinetd. or 5. Figure 20-1. select the service from the list and click the appropriate button on the toolbar (or choose the action from the Actions pulldown menu). The Services Configuration Tool lists the services from the /etc/rc. xinetd is also configured to remember the setting. Services Configuration Tool The Services Configuration Tool displays the current runlevel as well as the runlevel you are currently editing. and 5) and which xinetd services are enabled. the status window displays the phrase xinetd service. If the service is not an xinetd service.d/init. If the service is an xinetd service. stop. . Controlling Access to Services 159 20. 4.
For all other services. To configure a different runlevel. To enable a non-xinetd service to start at boot time for the currently selected runlevel. select the runlevel from the Edit Runlevel pulldown menu. check the checkbox beside the name of the service in the list. If you change the value for the httpd service from checked to unchecked and then select Save Changes. so httpd is still running. 20. the runlevel is initialized without the httpd service running. xinetd is restarted. Do nothing else — You do not have to stop the httpd service. Stop the httpd service — Stop the service by selecting it from the list and clicking the Stop button. the runlevel is reconfigured. Use the up and down arrows to navigate up and down the list. Pressing the [F1] key displays a short description of the selected service. use the [Tab] key. A message appears stating that the service was stopped successfully. When you save changes to other services. the command ntsysv --level 345 configures runlevels 3. Controlling Access to Services For example. runlevel 3 is not reinitialized. only the current runlevel is configured. To move between the list of services and the Ok and Cancel buttons. 2. This option is recommended if you change the Start at Boot value of multiple services and want to activate the changes immediately. The next time xinetd is started. rsync is still enabled. To add a service to a runlevel. A * signifies that a service is set to on. assume you check rsync to enable it in runlevel 3 and then save the changes. specify one or more runlevels with the --level option. You can also use ntsysv to configure runlevels. but the changes do not take effect immediately. ntsysv The ntsysv utility provides a simple interface for activating or deactivating services. The rsync service is immediately enabled. and then select Actions => Add Service. apply the changes by selecting File => Save Changes from the pulldown menu. Reinitialize the runlevel — Reinitialize the runlevel by going to a shell prompt and typing the command telinit 3 (where 3 is the runlevel number). 4. the runlevel 3 configuration changes so that httpd is not started at boot time. select the service to be deleted from the list on the left. The runlevel configuration is changed. The ntsysv interface works like the text mode installation program. Warning Services managed by xinetd are immediately affected by ntsysv. select the runlevel from the Edit Runlevel pulldown menu. 3.160 Chapter 20. However. You can wait until the system is rebooted for the service to stop. The next time the system is booted. The space bar selects/unselects services and is also used to "press" the Ok and Cancel buttons. but the runlevel is not restarted. and the changes take place immediately.4. thus. You must stop or start the individual service with the command service . changes do not take effect immediately. Warning When you save changes to xinetd services. assume you are configuring runlevel 3. After configuring the runlevel. and 5. the changes do not take place immediately. and select Actions => Delete Service. By default. For example. You can use ntsysv to turn an xinetd-managed service on or off. To delete a service from a runlevel. For example. Select one of following options at this point: 1.
service's settings for each runlevel are displayed. if xinetd is running. You must stop or start the individual service with the command service daemon stop.1. and the command chkconfig finger on is executed. to turn nscd off in runlevels 3. In the previous example. If xinetd is running. use the following command: chkconfig --level 345 nscd off Warning Services managed by xinetd are immediately affected by chkconfig. finger is enabled. If you use chkconfig --list to query a service in /etc/rc. chkconfig. 20.conf. For example. 20. Installed Documentation • The man pages for ntsysv.6. for example. Additional Resources For more information. At the end of the list is a section for the services managed by xinetd. 4. For example. For example. finger is disabled. The chkconfig --list command displays a list of system services and whether they are started ( on) or stopped (off) in runlevels 0-6. Replace stop with start or restart to start or restart the service. finger is immediately enabled without having to restart xinetd manually. replace daemon with the name of the service you want to stop. 20. — The man page for the format of host access control files (in section 5 • man 5 hosts_access . httpd. for example.5. For example. the command chkconfig --list finger returns the following output: finger on As shown.6. chkconfig The chkconfig command can also be used to activate and deactivate services. of the man pages). If the chkconfig --list command is used to query a service managed by xinetd. Changes for other services do not take effect immediately after using chkconfig. Replace stop with start or restart to start or restart the service.d. finger is enabled as an xinetd service. replace daemon with the name of the service you want to stop.Chapter 20. xinetd. In the previous example. it displays whether the xinetd service is enabled (on) or disabled (off). and xinetd. refer to the following resources. and 5. Controlling Access to Services 161 daemon stop. the command chkconfig --list httpd returns the following output: httpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off chkconfig can also be used to configure a service to be started (or not) in a specific runlevel. httpd.
• . It also provides instructions for creating iptables firewall rules. It contains a more detailed list of features and sample configuration files. — This manual discusses securing services with TCP wrappers and xinetd such as logging denied connection attempts.xinetd. Useful Websites • http://www. — This companion manual contains detailed information about how TCP wrappers and xinetd allow or deny access as well as how to configure network access using them.2.6. Controlling Access to Services 20.6.org — The xinetd webpage. 20. Inc. Related Books • Red Hat Enterprise Linux Reference Guide.3.162 Chapter 20. Red Hat Enterprise Linux Security Guide Red Hat. Inc. Red Hat.
which uses RSA keys as the default. the default protocol is version 2. To stop the OpenSSH server. refer to Chapter 20 Controlling Access to Services for information on how to manage services. rlogin. If you want the daemon to start automatically at boot time. It replaces telnet. if you are running the X Window System on your local machine. The OpenSSH daemon uses the configuration file /etc/ssh/sshd_config. open source implementation of the SSH (Secure SHell) protocols. All communications using OpenSSH tools. The openssh-server package is required and depends on the openssh package. If you want to configure the daemon in ways not provided by the default sshd_config. read the sshd man page for a list of the keywords that can be defined in the configuration file. you must first make sure that you have the proper RPM packages installed. Another reason to use OpenSSH is that it automatically forwards the DISPLAY variable to the client machine. and your system could be compromised by an unauthorized person logging in to your system using one of the intercepted passwords. they will not receive the warning message. 21. This feature is convenient if you prefer graphical system administration tools but do not always have physical access to your server. ftp. The default configuration file should be sufficient for most purposes. If you reinstall.5. Any clients who had connected to the system with any of the OpenSSH tools before the reinstall will see the following message: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! Someone could be eavesdropping on you right now (man-in-the-middle attack)! It is also possible that the RSA host key has just been changed. and 2 of the SSH protocol. are encrypted. backup the /etc/ssh/ssh_host*key* files and restore them after the reinstall. OpenSSH supports versions 1. rsh.9. the reinstalled system creates a new set of identification keys. you are enhancing the security of your machine. If you want to keep the host keys generated for the system. In other words. . encrypted network connectivity tools.3. when you run a program on the remote machine that requires X. Configuring an OpenSSH Server To run an OpenSSH server.Chapter 21. Since OpenSSH version 2. use the command /sbin/service sshd stop. the passwords can be retrieved. This process retains the system's identity. The information can be intercepted. use the command /sbin/service sshd start. 21.1. The OpenSSH set of utilities should be used whenever possible to avoid these security problems. and you log in to a remote machine using the ssh command. it will be displayed on your local machine. To start the OpenSSH service. Telnet and ftp use plain text passwords and send all information unencrypted. and when clients try to connect to the system after the reinstall.2. and rcp with secure. OpenSSH OpenSSH is a free. Why Use OpenSSH? If you use OpenSSH tools. including passwords. 1.
you will see a message similar to the following: The authenticity of host 'penguin. Next. if you want to execute the command ls /usr/share/doc on the remote machine penguin. you must have the openssh-clients and 21. The ssh command can be used to execute a command on the remote machine without logging in to a shell prompt.example.net. Logging in to a remote machine with ssh is similar to using telnet. Using the ssh Command The ssh command is a secure replacement for the rlogin. 21.example.3. Configuring an OpenSSH Client openssh packages installed on the client machine. This will add the server to your list of known hosts (~/. DSA key fingerprint is 94:68:3a:3a:bc:f3:9a:9b:01:5d:b3:07:38:e2:11:0c. you will be at a shell prompt for the remote machine.3. It is similar to rcp. which can be a new filename such as .example. To log in to a remote machine named penguin. and you will return to your local shell prompt. If you want to specify a different username.example.example. the contents of the remote directory /usr/share/doc will be displayed. The syntax is ssh hostname command . use the following command: ssh username@penguin. Using the scp Command The scp command can be used to transfer files between machines over a secure. For example. To connect to an OpenSSH server from a client machine.164 Chapter 21. such as /var/log/maillog. encrypted connection. type the following command at a shell prompt: ssh penguin. Are you sure you want to continue connecting (yes/no)? Type yes to continue.example.ssh/known_hosts/) as seen in the following message: Warning: Permanently added 'penguin. The <remotefile> specifies the destination. If you do not specify a username the username that you are logged in as on the local client machine is passed to the remote machine. type the following command at a shell prompt: ssh penguin.net You can also use the syntax ssh -l username penguin.net.example.net.net ls /usr/share/doc After you enter the correct password.example. rsh.2. After entering your password.net' (RSA) to the list of known hosts.net' can't be established. you will see a prompt asking for your password for the remote machine. It allows you to log in to a remote machine as well as execute commands on a remote machine. OpenSSH 21.1.3. and telnet commands. The general syntax to transfer a local file to a remote system is as follows: scp <localfile> username@tohostname:<remotefile> The <localfile> specifies the source including path to the file.net The first time you ssh to a remote machine.
The sftp utility is only available in OpenSSH version 2.0p1 and higher. Red Hat Enterprise Linux 4 uses SSH Protocol 2 and RSA keys by default. The general syntax is sftp username@hostname. and <newlocalfile> specifies the destination including path.ssh/authorized_keys2. Using the sftp Command The sftp utility can be used to open a secure.ssh/known_hosts2. downloads/ to an existing directory called uploads/ on the remote machine penguin. Generating Key Pairs If you do not want to enter your password every time you use ssh. execute the command man sftp at a shell prompt. use the following steps as the user who wants to connect to remote machines.example. Tip If you reinstall and want to save your generated key pair.3. 21. This process can be done for all users on your system. Alternately.5. to transfer the contents of the directory type the following at a shell prompt: scp downloads/* username@penguin. OpenSSH 165 /tmp/hostname-maillog. interactive FTP session.Chapter 21. If you complete the steps as root. copy this directory back to your home directory. if you do not have a preceding /. It is similar to ftp except that it uses a secure.example. To generate keys for a user.net:uploads/ 21. Refer to the sftp man page for a list of these commands. only root will be able to use the keys. ~/.net. Starting with OpenSSH version 3. including root. scp.0. ~/. To transfer the local file shadowman to the home directory of your account on penguin. SSH Protocol 1 and 2 share the ~/.net. you can leave off the final shadowman in the scp command.3.net. Multiple files can be specified as the source files. For the remote system. typically /home/username/.3. you can generate an authorization key pair.example.4.ssh/authorized_keys. you can use a set of commands similar to those used by FTP.example. ~/. The general syntax to transfer a remote file to the local system is as follows: scp username@tohostname:<remotefile> <newlocalfile> on The <remotefile> specifies the source including path. type the following at a shell prompt (replace username with your username): scp shadowman firstname.lastname@example.com/known_hosts. After reinstalling. Once authenticated. and /etc/ssh/ssh_known_hosts files. or sftp to connect to a remote machine. For example. the path will be relative to the home directory of username. encrypted connection. Keys must be generated for each user.ssh directory in your home directory.net:shadowman This will transfer the local file shadowman to /home/username/shadowman penguin.example. To read the man page. backup the . and /etc/ssh_known_hosts2 are obsolete. .com.
ssh/authorized_keys on the other machine. The public key is written to ~/. Generating an RSA Key Pair for Version 2 Use the following steps to generate an RSA key pair for version 2 of the SSH protocol.ssh/authorized_keys .ssh/id_dsa. skip to Section 21. 1.3.4. Copy the contents of ~/. append the contents of the file ~/. OpenSSH 21. To generate a DSA key pair to work with version 2 of the protocol.pub to the file ~/.ssh/id_rsa.ssh/id_dsa.ssh/id_rsa. The private key is written to ~/. If you are not running the X Window System.4.ssh/id_rsa.3. Enter a passphrase different from your account password and confirm it by entering it again.ssh/authorized_keys 5.1. Passphrases differ from passwords in that you can use spaces or tabs in the passphrase.pub into the file ~/. To generate an RSA key pair to work with version 2 of the protocol.ssh/authorized_keys on the machine to which you want to connect. Never distribute your private key to anyone.4 Configuring ssh-agent with GNOME.pub. Change the permissions of the .ssh/id_dsa.ssh/authorized_keys on the machine to which you want to connect.ssh/id_dsa.ssh 3.ssh/authorized_keys on the other machine.ssh 3.ssh directory using the following command: chmod 755 ~/.ssh/id_rsa.3. Tip A passphrase is a string of words and characters used to authenticate a user.pub to the file ~/. 4.pub into the file ~/.ssh/id_dsa. append the contents of the file ~/.3.ssh directory with the following command: chmod 755 ~/.pub.4.2.5 Configuring ssh-agent. Passphrases are generally longer than passwords because they are usually phrases instead of a single word.ssh/authorized_keys exist. This is the default starting with OpenSSH 2. If you are running GNOME. type the following command at a shell prompt: ssh-keygen -t dsa Accept the default file location of ~/. 21. skip to Section 21.ssh/id_rsa. Change the permissions of the . The public key is written to ~/. type the following command at a shell prompt: ssh-keygen -t rsa Accept the default file location of ~/.166 Chapter 21. Change the permissions of the authorized_keys file using the following command: chmod 644 ~/. Generating a DSA Key Pair for Version 2 Use the following steps to generate a DSA key pair for version 2 of the SSH Protocol. It is important never to give anyone the private key.4. If the file ~/. The private key is written to ~/. Enter a passphrase different from your account password and confirm it by entering it again. 2. 1.ssh/authorized_keys exist.9. 4. Copy the contents of ~/. Change the permissions of the authorized_keys file using the following command: chmod 644 ~/. 2. If the file ~/.
you should not be prompted for a password by ssh.Chapter 21. After GNOME is started. Select Main Menu Button (on the Panel) => Preferences => More Preferences => Sessions. in other words.5 Configuring ssh-agent. If the file ~/. Configuring ssh-agent with GNOME The ssh-agent utility can be used to save your passphrase so that you do not have to enter it each time you initiate an ssh or scp connection. or sftp. you will be prompted for both. skip to Section 21.5 Configuring ssh-agent. OpenSSH 167 5. 1. 2.3 and 1. If you have both DSA and RSA key pairs configured. 21.4. Click Close to exit the program. 2. . type the following command at a shell prompt: ssh-keygen -t rsa1 Accept the default file location (~/. The higher the priority number.3. skip to Section 21.ssh/authorized_keys on the remote machine.4. or using Red Hat Network. 3. To generate an RSA (for version 1. If you are using GNOME. restart X. Copy the contents of ~/. Change the permissions of your . you can use the command rpm -q openssh-askpass-gnome to determine if it is installed or not. To save your passphrase during your GNOME session. From this point on. 3. The private key is written to ~/.ssh/authorized_keys does not exist.4 Configuring ssh-agent with GNOME. you do not need an RSA version 1.pub into the file ~/. scp.3 or RSA version 1. Set it a priority to a number higher than any existing commands to ensure that it is executed last. from a Red Hat FTP mirror site. Enter a passphrase different from your account password. Generating an RSA Key Pair for Version 1. If you are running GNOME. the lower the priority.pub.4. Do not give anyone the private key.5 key pair.5 Use the following steps to generate an RSA key pair. which is used by version 1 of the SSH Protocol. You will need to have the package openssh-askpass-gnome installed. Confirm the passphrase by entering it again. Click Add and enter /usr/bin/ssh-add in the Startup Command text area. If you are only connecting between systems that use DSA. If you are not running GNOME. A good priority number for ssh-add is 70 or higher.ssh and chmod 644 ~/. skip to Section 21. 21.5 Configuring ssh-agent.3.3.ssh/identity.ssh directory and your key with the commands chmod 755 ~/. If you are not running the X Window System. you can copy the file ~/.3 and 1. the openssh-askpass-gnome package contains the application used to prompt you for your passphrase when you log in to GNOME and save it until you log out of GNOME. install it from your Red Hat Enterprise Linux CD-ROM set.ssh/identity.3. this one should have the lowest priority. follow the following steps: 1. 4.4 Configuring ssh-agent with GNOME.4. If it is not installed.pub.ssh/identity. If you have other programs listed. You will not have to enter your password or passphrase for any ssh or scp connection made during that GNOME session. If you are not using GNOME.3.4. skip to Section 21.ssh/authorized_keys on the machine to which you wish to connect.ssh/identity. a dialog box will appear prompting you for your passphrase(s).4.5 protocol) key pair.3. If you are running GNOME.3.ssh/identity).4.pub to the file ~/.4. refer to Section 21.ssh/identity. The public key is written to ~/. Enter the passphrase requested. and click on the Startup Programs tab.3. Log out and then log back into GNOME.
Configuring ssh-agent The ssh-agent can be used to store your passphrase so that you do not have to enter it each time you make a ssh or scp connection. this procedure will work in a terminal window.4 Configuring ssh-agent with GNOME). When you log out. your passphrase will only be remembered for that terminal window.openssh.4. If you have more than one key pair configured. and the most up-to-date information for them is available from their websites. sftp.3. Installed Documentation • The ssh. Then type the command: ssh-add and enter your passphrase(s). follow these steps from a shell prompt. 1. it is not a global setting.4. Useful Websites • • • http://www. 21. mailing lists. mailing lists.168 Chapter 21.4. 3. bug reports. project goals. http://www. However. At a shell prompt. type the following command: exec /usr/bin/ssh-agent $SHELL 2.4. review a list of configuration files. such as an XTerm. 21.4. OpenSSH 21. scp. You must execute these two commands each time you log in to a virtual console or open a terminal window.org/ — SSH client software for other platforms. .freessh.4. and ssh-keygen man pages — These man pages include information on how to use these commands as well as all the parameters that can be used with them. and discover how SSH can be used for X forwarding. your passphrase(s) will be forgotten. The man pages for OpenSSH and OpenSSL tools are also good sources of detailed information.com/ — The OpenSSH FAQ page. and a description of the project goal. sshd. this procedure will work in a terminal window.openssl. 21. If you are running X but not GNOME. If you are running GNOME but you do not want to configure it to prompt you for your passphrase when you log in (refer to Section 21.2.1. you will be prompted for each one.5. 21. Additional Resources The OpenSSH and OpenSSL projects are in constant development. Related Books • Red Hat Enterprise Linux Reference Guide — Learn the event sequence of an SSH connection. and a more technical explanation of the security features. If you are not running the X Window System. http://www.3.org/ — The OpenSSL FAQ page.3.
Mounting NFS File Systems Use the mount command to mount a shared NFS directory from another machine: mount shadowman. The line must state the hostname of the NFS server.1. and /misc/local is the location to mount the file system on the local machine.intr The mount point /pub must exist on the client machine before this command can be executed.1. which means that it can export file systems to other systems and mount file systems exported from other machines.example. Mounting NFS File Systems using /etc/fstab An alternate way to mount an NFS share from another machine is to add a line to the /etc/fstab file.com. In this command. 22. and the directory on the local machine where the NFS share is to be mounted.example. /misc/export is the directory that shadowman is exporting. Red Hat Enterprise Linux can be both an NFS server and an NFS client.2. shadowman. After adding this line to /etc/fstab on the client system.com:/misc/export /misc/local Warning The mount point directory on the local machine (/misc/local in the above example) must exist before this command can be executed. the user goes into the /myproject directory on his machine. Why Use NFS? NFS is useful for sharing directories of files between multiple users on the same network.example. There are no passwords to enter or special commands to remember. a group of users working on the same project can have access to the files for that project using a shared directory of the NFS file system (commonly known as an NFS share) mounted in the directory /myproject.timeo=14. .example. Network File System (NFS) Network File System (NFS) is a way to share files between machines on a network as if the files were located on the client's local hard drive.wsize=8192. Users work as if the directory is on their local machines. For example. 22.Chapter 22. 22.2. The general syntax for the line in /etc/fstab is as follows: server:/usr/local/pub /pub nfs rsize=8192. the directory on the server being exported. After the mount command runs (and if the client has proper permissions from the shadowman.com NFS server) the client user can execute the command ls /misc/local to display a listing of the files in /misc/export on shadowman.com is the hostname of the NFS file server. and the mount point /pub is mounted from the server. To access the shared files. You must be root to modify the /etc/fstab file. type the command mount /pub at a shell prompt.
Note The directory /misc must exist on the local file system. The second field contains mount options such as rw for read and write access.master file. The first field is the mount point. This directory is created dynamically by automount. The third field can contain information such as a timeout value.master has three fields.170 Chapter 22. . For example.master: /misc /etc/auto.misc is the name of the /misc subdirectory. Each entry in auto. The third field is the location of the NFS export including the hostname and directory. and for information on managing services.wsize=8192 penguin. at a shell prompt. add the following line to auto. It should not actually exist on the client machine.intr. the /etc/auto. The second field is the location of the map file.misc file might define mount points in the /misc directory.example.rsize=8192.net at the mount point /misc/myproject on your machine. There should be no subdirectories in /misc on the local file system.misc: myproject -rw.example.2.misc --timeout 60 Next. and the third field is optional. add the following line to /etc/auto. To start the autofs service. type the following command: /sbin/service autofs restart To view the active mount points.master to determine which mount points are defined. For example. Mounting NFS File Systems using autofs A third option for mounting an NFS share is the use of the autofs service.soft. type the following command at a shell prompt: /sbin/service autofs status If you modify the /etc/auto. this relationship would be defined in the /etc/auto. to mount the directory /proj52 on the remote machine penguin. Network File System (NFS) 22. refer to Chapter 20 Controlling Access to Services. It then starts an automount process with the appropriate parameters for each mount point. Autofs uses the automount daemon to manage your mount points by only mounting them dynamically when they are accessed. Autofs consults the master map configuration file /etc/auto.2. you must tell the automount daemon(s) to reload by typing the following command at a shell prompt: /sbin/service autofs reload To learn how to configure autofs to start at boot time. Each line in the master map defines a mount point and a separate map file that defines the file systems to be mounted under this mount point.net:/proj52 The first field in /etc/auto.master configuration file while autofs is running.
There are three ways to configure an NFS file system export.example. To use NFS over UDP. Because of TCP's reliability. For example. unlike UDP which only acknowledges completion. Performance gain on heavily loaded networks because TCP acknowledges every packet. • The main disadvantage is that there is a very small performance hit due to the overhead associated with the TCP protocol. available for NIS enabled workstations: myproject -rw.misc (server side with NIS). however. The NFS Server Configuration Tool can be used to configure a system as an NFS server.3.2.wsize=8192.udp When the NFS mount is specified in an autofs configuration file for a NIS server. On a very congested network. The advantages of using TCP include the following: • • • Improved connection durability. the NFS-exported file system is accessed via TCP. thus less NFS stale file handles messages.timeo=14. automatically via the /etc/fstab file (client side).intr. TCP has better congestion control than UDP (which has none). they are used by the NFS client as well. Exporting NFS File Systems Sharing or serving files from an NFS server is known as exporting the directories. . 22. When a TCP connection breaks (due to the server being unavailable) the client stops sending data and restarts the connection process once the server becomes available. On demand via the command line (client side). include the -o udp option to mount when mounting the NFS-exported file system on the client system. since it's connection-less. Using TCP The default transport protocol for NFSv4 is TCP. UDP packets are the first packets that are dropped.Chapter 22. With UDP. Network File System (NFS) 171 22.3.example. if the -o udp option is not specified.com:/misc/export /misc/local When the NFS mount is specified in /etc/fstab (client side): server:/usr/local/pub /pub nfs rsize=8192.soft.net:/proj52 Since the default is TCP. Error detection. the client continues to pound the network with data until the server reestablishes a connection. if an ext3 file system has ACLs enabled for it and is NFS exported. 22. and if the NFS client can read ACLs. Preserving ACLs The Red Hat Enterprise Linux 4 kernel provides ACL support for the ext3 file system and ext3 file systems mounted with the NFS or Samba protocols. only parts of that 8K data are transmitted at a time. such as /etc/auto. Thus.intr. and automatically via autofs configuration files. on demand via the command line (client side): mount -o udp shadowman.rsize=8192.4. This means that if NFS is writing data (in 8K chunks) all of that 8K must be retransmitted over UDP.wsize=8192.udp penguin.master and /etc/auto.2. the Red Hat Enterprise Linux 4 kernel includes support for NFS over UDP.
Chapter 22. Network File System (NFS)
To use the NFS Server Configuration Tool, you must be running the X Window System, have root privileges, and have the system-config-nfs RPM package installed. To start the application, select the Main Menu Button (on the Panel) => System Settings => Server Settings => NFS, or type the command system-config-nfs.
Figure 22-1. NFS Server Configuration Tool To add an NFS share, click the Add button. The dialog box shown in Figure 22-2 appears. The Basic tab requires the following information:
• • •
Directory — Specify the directory to share, such as /tmp. Host(s) — Specify the host(s) with which to share the Section 22.3.2 Hostname Formats for an explanation of possible formats. directory. Refer to
Basic permissions — Specify whether the directory should have read-only or read/write permissions.
Figure 22-2. Add Share The General Options tab allows the following options to be configured:
Allow connections from port 1024 and higher — Services started on port numbers less than 1024 must be started as root. Select this option to allow the NFS service to be started by a user other than root. This option corresponds to insecure. Allow insecure file locking — Do not require a lock request. This option corresponds to insecure_locks. Disable subtree checking — If a subdirectory of a file system is exported, but the entire file system is not exported, the server checks to see if the requested file is in the subdirectory exported. This check is called subtree checking. Select this option to disable subtree checking. If the entire file
• •
Chapter 22. Network File System (NFS)
system is exported, selecting to disable subtree checking can increase the transfer rate. This option corresponds to no_subtree_check.
Sync write operations on request — Enabled by default, this option does not allow the server to reply to requests before the changes made by the request are written to the disk. This option corresponds to sync. If this is not selected, the async option is used.
Force sync of write operations immediately — Do not delay writing to disk. This option corresponds to no_wdelay.
The User Access tab allows the following options to be configured:
Treat remote root user as local root — By default, the user and group IDs of the root user are both 0. Root squashing maps the user ID 0 and the group ID 0 to the user and group IDs of anonymous so that root on the client does not have root privileges on the NFS server. If this option is selected, root is not mapped to anonymous, and root on a client has root privileges to exported directories. Selecting this option can greatly decrease the security of the system. Do not select it unless it is absolutely necessary. This option corresponds to no_root_squash. Treat all client users as anonymous users — If this option is selected, all user and group IDs are mapped to the anonymous user. This option corresponds to all_squash.
Specify local user ID for anonymous users — If Treat all client users as anonymous users is selected, this option lets you specify a user ID for the anonymous user. This option corresponds to anonuid. Specify local group ID for anonymous users — If Treat all client users as anonymous users is selected, this option lets you specify a group ID for the anonymous user. This option corresponds to anongid.
To edit an existing NFS share, select the share from the list, and click the Properties button. To delete an existing NFS share, select the share from the list, and click the Delete button. After clicking OK to add, edit, or delete an NFS share from the list, the changes take place immediately — the server daemon is restarted and the old configuration file is saved as /etc/exports.bak. The new configuration is written to /etc/exports. The NFS Server Configuration Tool reads and writes directly to the /etc/exports configuration file. Thus, the file can be modified manually after using the tool, and the tool can be used after modifying the file manually (provided the file was modified with correct syntax).
22.3.1. Command Line Configuration
If you prefer editing configuration files using a text editor or if you do not have the X Window System installed, you can modify the configuration file directly. The /etc/exports file controls what directories the NFS server exports. Its format is as follows:
directory hostname(options)
The only option that needs to be specified is one of sync or async (sync is recommended). If sync is specified, the server does not reply to requests before the changes made by the request are written to the disk. For example,
Chapter 22. Network File System (NFS)
would allow users from speedy.example.com to mount /misc/export with the default read-only permissions, but,
would allow users from speedy.example.com to mount /misc/export with read/write privileges. Refer to Section 22.3.2 Hostname Formats for an explanation of possible hostname formats. Refer to the Red Hat Enterprise Linux Reference Guide for a list of options that can be specified.
Caution Be careful with spaces in the /etc/exports file. If there are no spaces between the hostname and the options in parentheses, the options apply only to the hostname. If there is a space between the hostname and the options, the options apply to the rest of the world. For example, examine the following lines:
/misc/export speedy.example.com(rw,sync) /misc/export speedy.example.com (rw,sync)
The first line grants users from speedy.example.com read-write access and denies all other users. The second line grants users from speedy.example.com read-only access (the default) and allows the rest of the world read-write access.
Each time you change /etc/exports, you must inform the NFS daemon of the change, or reload the configuration file with the following command:
/sbin/service nfs reload
22.3.2. Hostname Formats
The host(s) can be in the following forms:
• •
Single machine — A fully qualified domain name (that can be resolved by the server), hostname (that can be resolved by the server), or an IP address. Series of machines specified with wildcards — Use the * or ? character to specify a string match. Wildcards are not to be used with IP addresses; however, they may accidentally work if reverse DNS lookups fail. When specifying wildcards in fully qualified domain names, dots (.) are not included in the wildcard. For example, *.example.com includes one.example.com but does not include one.two.example.com. IP networks — Use a.b.c.d/z, where a.b.c.d is the network and z is the number of bits in the netmask (for example 192.168.0.0/24). Another acceptable format is a.b.c.d/netmask, where a.b.c.d is the network and netmask is the netmask (for example, 192.168.100.8/255.255.255.0). Netgroups — In the format @group-name, where group-name is the NIS netgroup name.
22.3.3. Starting and Stopping the Server
On the server that is exporting NFS file systems, the nfs service must be running. View the status of the NFS daemon with the following command:
Chapter 22. Network File System (NFS)
/sbin/service nfs status
Start the NFS daemon with the following command:
/sbin/service nfs start
Stop the NFS daemon with the following command:
/sbin/service nfs stop
To start the nfs service at boot time, use the command:
/sbin/chkconfig --level 345 nfs on
You can also use chkconfig, ntsysv or the Services Configuration Tool to configure which services start at boot time. Refer to Chapter 20 Controlling Access to Services for details.
22.4. Additional Resources
This chapter discusses the basics of using NFS. For more detailed information, refer to the following resources.
22.4.1. Installed Documentation
The man pages for nfsd, mountd, exports, auto.master, and autofs (in manual sections 5 and 8) — These man pages show the correct syntax for the NFS and autofs configuration files.
22.4.2. Useful Websites
• •
http://nfs.sourceforge.net/ — the NFS webpage, includes links to the mailing lists and FAQs. http://www.tldp.org/HOWTO/NFS-HOWTO/index.html — The Linux NFS-HOWTO from the Linux Documentation Project.
22.4.3. Related Books
Managing NFS and NIS Services by Hal Stern; O'Reilly & Associates, Inc.
Chapter 22. Network File System (NFS)
Chapter 23.
Samba uses the SMB protocol to share files and printers across a network connection. Operating systems that support this protocol include Microsoft Windows, OS/2, and Linux. The Red Hat Enterprise Linux 4 kernel contains Access Control List (ACL) support for ext3 file systems. If the Samba server shares an ext3 file system with ACLs enabled for it, and the kernel on the client system contains support for reading ACLs from ext3 file systems, the client automatically recognizes and uses the ACLs.
23.1. Why Use Samba?
Samba is useful if you have a network of both Windows and Linux machines. Samba allows files and printers to be shared by all the systems in a network. To share files between Linux machines only, use NFS as discussed in Chapter 22 Network File System (NFS). To share printers between Linux machines only, you do not need to use Samba; refer to Chapter 34 Printer Configuration.
23.2. Configuring a Samba Server
The default configuration file (/etc/samba/smb.conf) allows users to view their home directories as a Samba share. It also shares all printers configured for the system as Samba shared printers. In other words, you can attach a printer to the system and print to it from the Windows machines on your network.
23.2.1. Graphical Configuration
To configure Samba using a graphical interface, use the Samba Server Configuration Tool. For command line configuration, skip to Section 23.2.2 Command Line Configuration. The Samba Server Configuration Tool is a graphical interface for managing Samba shares, users, and basic server settings. It modifies the configuration files in the /etc/samba/ directory. Any changes to these files not made using the application are preserved. To use this application, you must be running the X Window System, have root privileges, and have the system-config-samba RPM package installed. To start the Samba Server Configuration Tool from the desktop, go to the Main Menu Button (on the Panel) => System Settings => Server Settings => Samba or type the command system-config-samba at a shell prompt (for example, in an XTerm or a GNOME terminal).
Figure 23-1. Samba Server Configuration Tool
Chapter 23. Samba
Note The Samba Server Configuration Tool does not display shared printers or the default stanza that allows users to view their own home directories on the Samba server.
220.127.116.11. Configuring Server Settings
The first step in configuring a Samba server is to configure the basic settings for the server and a few security options. After starting the application, select Preferences => Server Settings from the pulldown menu. The Basic tab is displayed as shown in Figure 23-2.
Figure 23-2. Configuring Basic Server Settings On the Basic tab, specify which workgroup the computer should be in as well as a brief description of the computer. They correspond to the workgroup and server string options in smb.conf.
Figure 23-3. Configuring Security Server Settings The Security tab contains the following options:
Authentication Mode — This corresponds to the security option. Select one of the following types of authentication.
ADS — The Samba server acts as a domain member in an Active Directory Domain (ADS) realm. For this option, Kerberos must be installed and configured on the server, and Samba must become a member of the ADS realm using the net utility, which is part of the samba-client
When guests log in to the Samba server.1. User — (Default) Samba users must provide a valid username and password on a per Samba server basis. the changes take effect immediately.Chapter 23.2. they have the same privileges as this user. they must be mapped to a valid user on the server.3 Encrypted Passwords for more information about encrypted Samba passwords. Guest Account — When users or guest users log into a Samba server. Windows NT 4. • Domain — The Samba server relies on a Windows NT Primary or Backup Domain Controller to verify the user. Specify the NetBIOS name of the other Samba server in the Authentication Server field. The Encrypted Passwords option must be set to Yes if this is selected. This option does not configure Samba to be an ADS Controller.COM. Select one of the existing usernames on the system to be the guest Samba account. This corresponds to the encrypted passwords option. The Samba user is associated with the existing user account. or other more recent versions of Microsoft Windows. Use of your Samba server as a domain member in an ADS realm assumes proper configuration of Kerberos. They are not prompted for a username and password until they try to connect to a specific shared directory from a Samba server. Managing Samba Users The Samba Server Configuration Tool requires that an existing user account be active on the system acting as the Samba server before a Samba user can be added. Server — The Samba server tries to verify the username and password combination by passing them to another Samba server.2. thus. This corresponds to the guest account option. Refer to Section 23.1.conf file. .2 Managing Samba Users for details. the server tries to verify using the user authentication mode. Refer to the net man page for details. • • • • Encrypt Passwords — This option must be enabled if the clients are connecting from a system with Windows 98.2. Note The Kerberos Realm field must be supplied in all uppercase letters.0 with Service Pack 3. Share — Samba users do not have to enter a username and password combination on a per Samba server basis. the changes are written to the configuration file and the daemon is restart. Specify the NetBIOS name of the Primary or Backup Domain Controller in the Authentication Server field. Samba 179 package. such as EXAMPLE.2. • After clicking OK. Select this option if you want the Windows Username option to work. The passwords are transfered between the server and the client in an encrypted format instead of as a plain-text word that can be intercepted. including the /etc/krb5. If it can not. Refer to Section 23. Specify the realm of the Kerberos server in the Kerberos Realm field. 23. The server passes the username and password to the Controller and waits for it to return.
To delete an existing Samba user. Managing Samba Users To add a Samba user. specify that Windows username in the Windows Username field. Deleting a Samba user does not delete the associated system user account.1. and click the Add User button. it is recommended that the Samba passwords for all users are different from their system passwords. select the user from the list. Also configure a Samba Password for the Samba User and confirm it by typing it again. and click Edit User. select the user. Even if you select to use encrypted passwords for Samba. If the user has a different username on a Windows machine and needs to log into the Samba server from the Windows machine. In the Create New Samba User window select a Unix Username from the list of existing users on the local system. and click the Delete User button. select Preferences => Samba Users from the pulldown menu. The users are modified immediately after clicking the OK button. 23. click the Add button from the main Samba configuration window. The Authentication Mode on the Security tab of the Server Settings preferences must be set to User for this option to work. Adding a Share The Basic tab configures the following options: . Samba Figure 23-4. Adding a Share To create a Samba share. Figure 23-5.180 Chapter 23. To edit an existing user.2.3.
Windows 2000. on the Samba server. edit the following lines in your smb. and Windows XP require encrypted Samba passwords. Samba • • • • 181 Directory — The directory to share via Samba. Encrypted Passwords Encrypted passwords are enabled by default because it is more secure.conf file (after modifying it to reflect your needs and your system): [sharename] comment = Insert a comment here path = /home/share/ valid users = tfox carole public = no writable = yes printable = no create mask = 0765 The above example allows the users tfox and carole to read and write to the directory /home/share. If you select to allow access to specific users.3. 23.2. The directory must exist before it can be entered here. The share is added immediately after clicking OK. To specify the Windows workgroup and a brief description of the Samba server. The BRIEF COMMENT ABOUT SERVER is optional and is used as the Windows comment about the Samba system.2. To use Samba between a Linux system and a system running one of these Windows operating systems. To create a Samba share directory on your Linux system.conf file: workgroup = WORKGROUPNAME server string = BRIEF COMMENT ABOUT SERVER Replace WORKGROUPNAME with the name of the Windows workgroup to which this machine should belong.Chapter 23. Windows 98. On the Access tab. Windows ME.conf as its configuration file. Basic Permissions — Whether users should only be able to read the files in the shared directory or whether they should be able to read and write to the shared directory. select the users from the list of available Samba users. If you choose to modify your . The Microsoft SMB Protocol originally used plain text passwords. from a Samba client.2. Windows NT 4. select whether to allow only specified users to access the share or whether to allow all Samba users to access the share. add the following section to your smb. but can be configured. It is recommended that encrypted passwords be used. Command Line Configuration Samba uses /etc/samba/smb. 23. which can be intercepted by someone using a network packet sniffer. Descriptions — A brief description of the share. the changes do not take effect until you restart the Samba daemon with the command service smb restart. you can either edit your Windows registry to use plaintext passwords or configure Samba on your Linux system to use encrypted passwords. However.0 with Service Pack 3 or higher. it is the same value as Directory. Share name — The actual name of the share that is seen from remote machines. plain text passwords are used. By default. If encrypted passwords are not used. If you change this configuration file.
Make sure the smb service is started by typing the command service smb restart at a shell prompt. type the following command: cat /etc/passwd | mksmbpasswd. or the Services Configuration Tool to enable it at runtime. at a shell prompt. If a user invokes the passwd command. The script does not copy user passwords to the new file. it is recommended that the user's Samba password be different from the user's system password. add the following lines to etc/samba/smb. use the following command (replace username with each user's username): smbpasswd username 4. Samba registry. use ntsysv. In the file /etc/samba/smb. Encrypted passwords must be enabled. 2.so nullok use_authtok try_first_pass 23.d/system-auth below the password required /lib/security/pam_smbpass. To set each Samba user's password.sh > /etc/samba/smbpasswd The mksmbpasswd.sh > /etc/samba/smbpasswd If the system uses NIS. View the status of the Samba daemon with the following command: . 6.sh script is installed in your /usr/bin directory with the samba package. add the following line to /etc/pam. pam_cracklib. the smb service must be running. Since they are enabled by default. chkconfig. Change the permissions of the Samba password file so that only root has read and write permissions: chmod 600 /etc/samba/smbpasswd 3. the password he uses to log in to the Red Hat Enterprise Linux system as well as the password he must provide to connect to a Samba share are changed. you must do so for all of your Windows machines — this is risky and may cause further conflicts. However. follow these steps: 1. To specifically enable encrypted passwords in the configuration file. If you want the smb service to start automatically. then the line is ignored. they do not have to be specifically enabled in the configuration file.4. It is recommended that you use encrypted passwords for better security. they can not be disabled in the configuration file either.conf: encrypt passwords = yes smb passwd file = /etc/samba/smbpasswd 5. To configure Samba to use encrypted passwords. and encrypted passwords are enabled. either remove it or comment it out. To create one based on your existing /etc/passwd file. Starting and Stopping the Server On the server that is sharing directories via Samba. The pam_smbpass PAM module can be used to sync users' Samba passwords with their system passwords when the passwd command is used. Refer to Chapter 20 Controlling Access to Services for details. Create a separate password file for Samba. verify that the following line does not exist: encrypt passwords = no If it does exist but is commented out with a semi-colon (. and a Samba user account is not active until a password is set for it.conf.) at the beginning of the line.182 Chapter 23. For higher security.2. type the following command: ypcat passwd | mksmbpasswd.so invocation: To enable this feature. If this line exists but is not commented out.
. execute the command smbstatus. As shown in Figure 23-6.3. SMB Workgroups in Nautilus Double-click one of the workgroup icons to view a list of computers within the workgroup. or the Services Configuration Tool to configure which services start at boot time. an icon appears for each available SMB workgroup on the network. Samba /sbin/service smb status 183 Start the daemon with the following command: /sbin/service smb start Stop the daemon with the following command: /sbin/service smb stop To start the smb service at boot time.Chapter 23. Figure 23-6. You can also type smb: in the Location: bar of Nautilus to view the workgroups. 23. use the command: /sbin/chkconfig --level 345 smb on You can also use chkconfig. Select Main Menu Button (on the Panel) => Network Servers to view a list of Samba workgroups on your network. Tip To view active connections to the system. ntsysv. Refer to Chapter 20 Controlling Access to Services for details. Connecting to a Samba Share You can use Nautilus to view available Samba shares on your network.
there is an icon for each machine within the workgroup. To exit smbclient. Enter the correct password or press [Enter] if no password is required for the user. type help for a list of commands. you have successfully logged in. Doubleclick on an icon to view the Samba shares on the machine. For each server found. replace sharename with your username. the username of the current user is passed to the Samba server. type the following command: smbclient //<hostname>/<sharename> -U <username> Replace <hostname> with the hostname or IP address of the Samba server you want to connect to. you are prompted for them. If you see the smb:\> prompt. If you wish to browse the contents of your home directory. operating system. To mount a Samba share to a directory. <sharename> with the name of the shared directory you want to browse. and <username> with the Samba username for the system. Once you are logged in. NetBIOS name. 23. it displays its IP address. use the findsmb command.184 Chapter 23.3. If a username and password combination is required.2. Command Line To query the network for Samba servers. create the directory if it does not already exist. If the -U switch is not used. type exit at the smb:\> prompt. and execute the following command as root: mount -t smbfs -o username=<username> //<servername>/<sharename> /mnt/point/ . you can also specify the Samba server and sharename in the Location: bar for Nautilus using the following syntax (replace <servername> and <sharename> with the appropriate values): smb://<servername>/<sharename>/ 23. Mounting the Share Sometimes it is useful to mount a Samba share to a directory so that the files in the directory can be treated as if they are part of the local file system. and SMB server version. Alternately.3. workgroup name. SMB Machines in Nautilus As you can see from Figure 23-7. To connect to a Samba share from a shell prompt.1. Samba Figure 23-7.
org/samba/docs/using_samba/toc.4. 2nd Edition by Jay Ts.4. Installed Documentation • smb. please refer to the following resources.2. and a list of GUI interfaces. Additional Resources For configuration options not covered here.Chapter 23. and David Collier-Brown. 23.samba. 23. http://www.samba.conf • smbd man page — explains how to configure the Samba configuration file and findsmb man pages — learn more about these client tools help files included with the samba man page — describes how the Samba daemon works • smbclient • /usr/share/doc/samba-<version-number>/docs/ — package 23.org/ — The Samba webpage contains useful documentation. O'Reilly & Associates .html — an online version of Using Samba.4.1. Samba 185 This command mounts <sharename> from <servername> in the local directory /mnt/point/. information about mailing lists. Useful Websites • • http://www. Robert Eckstein.
Chapter 23. Samba
Chapter 24.
Dynamic Host Configuration Protocol (DHCP)
Dynamic Host Configuration Protocol (DHCP) is a network protocol for automatically assigning TCP/IP information to client machines. Each DHCP client connects to the centrally-located DHCP server which returns that client's network configuration, including the IP address, gateway, and DNS servers.
24.1. Why Use DHCP?
DHCP is useful for automatic configuration of client network interfaces. When configuring the client system, the administrator can choose DHCP and instead of entering an IP address, netmask, gateway, or DNS servers. The client retrieves this information from the DHCP server. DHCP is also useful if an administrator wants to change the IP addresses of a large number of systems. Instead of reconfiguring all the systems, he can just edit one DHCP configuration file on the server for the new set of IP addresses. If the DNS servers for an organization changes, the changes are made on the DHCP server, not on the DHCP clients. Once the network is restarted on the clients (or the clients are rebooted), the changes take effect. Furthermore, if a laptop or any type of mobile computer is configured for DHCP, it can be moved from office to office without being reconfigured as long as each office has a DHCP server that allows it to connect to the network.
24.2. Configuring a DHCP Server
To configure a DHCP server, the /etc/dhcpd.conf configuration file must be created. A sample file can be found at /usr/share/doc/dhcp-<version>/dhcpd.conf.sample. DHCP also uses the file /var/lib/dhcp/dhcpd.leases to store the client lease database. Refer to Section 24.2.2 Lease Database for more information.
24.2.1. Configuration File
The first step in configuring a DHCP server is to create the configuration file that stores the network information for the clients. Global options can be declared for all clients, while other options can be declared for individual client systems. The configuration file can contain extra tabs or blank lines for easier formatting. Keywords are caseinsensitive and lines beginning with a hash mark (#) are considered comments. Two DNS update schemes are currently implemented — the ad-hoc DNS update mode and the interim DHCP-DNS interaction draft update mode. If and when these two are accepted as part of the Internet Engineering Task Force (IETF) standards process, there will be a third mode — the standard DNS update method. The DHCP server must be configured to use one of the two current schemes. Version 3.0b2pl11 and previous versions used the ad-hoc mode; however, it has been deprecated. To keep the same behavior, add the following line to the top of the configuration file:
ddns-update-style ad-hoc;
To use the recommended mode, add the following line to the top of the configuration file:
ddns-update-style interim;
Chapter 24. Dynamic Host Configuration Protocol (DHCP)
Refer to the dhcpd.conf man page for details about the different modes. There are two types of statements in the configuration file:
• •
Parameters — State how to perform a task, whether to perform a task, or what network configuration options to send to the client. Declarations — Describe the topology of the network, describe the clients, provide addresses for the clients, or apply a group of parameters to a group of declarations.
Some parameters must start with the option keyword and are referred to as options. Options configure DHCP options; whereas, parameters configure values that are not optional or control how the DHCP server behaves. Parameters (including options) declared before a section enclosed in curly brackets ({ }) are considered global parameters. Global parameters apply to all the sections below it.
Important If the configuration file is changed, the changes do not take effect until the DHCP daemon is restarted with the command service dhcpd restart.
Tip Instead of changing a DHCP configuration file and restarting the service each time, using the omshell command provides an interactive way to connect to, query, and change the configuration of a DHCP server. By using omshell, all changes can be made while the server is running. For more information on omshell, refer to the omshell man page.
In Example 24-1, the routers, subnet-mask, domain-name, domain-name-servers, and time-offset options are used for any host statements declared below it. Additionally, a subnet can be declared, a subnet declaration must be included for every subnet in the network. If it is not, the DHCP server fails to start. In this example, there are global options for every DHCP client in the subnet and a range declared. Clients are assigned an IP address within the range.
subnet 192.168.1.0 netmask 255.255.255.0 { option routers 192.168.1.254; option subnet-mask 255.255.255.0; option domain-name option domain-name-servers option time-offset range 192.168.1.10 192.168.1.100; } "example.com"; 192.168.1.1; -18000; # Eastern Standard Time
Example 24-1. Subnet Declaration All subnets that share the same physical network should be declared within a shared-network declaration as shown in Example 24-2. Parameters within the shared-network, but outside the enclosed
Chapter 24. Dynamic Host Configuration Protocol (DHCP)
should be a descriptive title for the network, such as using the title 'test-lab' to describe all the subnets in a test lab environment.
shared-network name { option domain-name "test.redhat.com"; option domain-name-servers ns1.redhat.com, ns2.redhat.com; option routers 192.168.0.254; more parameters for EXAMPLE shared-network subnet 192.168.1.0 netmask 255.255.252.0 { parameters for subnet range 192.168.1.1 192.168.1.254; } subnet 192.168.2.0 netmask 255.255.252.0 { parameters for subnet range 192.168.2.1 192.168.2.254; } }
subnet declarations, are considered to be global parameters. The name of the shared-network
Example 24-2. Shared-network Declaration As demonstrated in Example 24-3, the group declaration can be used to apply global parameters to a group of declarations. For example, shared networks, subnets, and hosts can be grouped.
group { option routers option subnet-mask option domain-name option domain-name-servers option time-offset
192.168.1.254; 255.255.255.0; "example.com"; 192.168.1.1; -18000; # Eastern Standard Time
host apex { option host-name "apex.example.com"; hardware ethernet 00:A0:78:8E:9E:AA; fixed-address 192.168.1.4; } host raleigh { option host-name "raleigh.example.com"; hardware ethernet 00:A1:DD:74:C3:F2; fixed-address 192.168.1.6; }
Example 24-3. Group Declaration To configure a DHCP server that leases a dynamic IP address to a system within a subnet, modify Example 24-4 with your values. It declares a default lease time, maximum lease time, and network configuration values for the clients. This example assigns IP addresses in the range 192.168.1.10 and 192.168.1.100 to client systems.
Chapter 24. Dynamic Host Configuration Protocol (DHCP)
default-lease-time 600; max-lease-time 7200; option subnet-mask 255.255.255.0; option broadcast-address 192.168.1.255; option routers 192.168.1.254; option domain-name-servers 192.168.1.1, 192.168.1.2; option domain-name "example.com"; subnet 192.168.1.0 netmask 255.255.255.0 { range 192.168.1.10 192.168.1.100; }
Example 24-4. Range Parameter To assign an IP address to a client based on the MAC address of the network interface card, use the hardware ethernet parameter within a host declaration. As demonstrated in Example 24-5, the host apex declaration specifies that the network interface card with the MAC address 00:A0:78:8E:9E:AA always receives the IP address 192.168.1.4. Note that the optional parameter host-name can also be used to assign a host name to the client.
host apex { option host-name "apex.example.com"; hardware ethernet 00:A0:78:8E:9E:AA; fixed-address 192.168.1.4; }
Example 24-5. Static IP Address using DHCP
Tip The sample configuration file provided can be used as a starting point and custom configuration options can be added to it. To copy it to the proper location, use the following command:
cp /usr/share/doc/dhcp-<version-number>/dhcpd.conf.sample /etc/dhcpd.conf
(where <version-number> is the DHCP version number).
For a complete list of option statements and what they do, refer to the dhcp-options man page.
24.2.2. Lease Database
On the DHCP server, the file /var/lib/dhcp/dhcpd.leases stores the DHCP client lease database. This file should not be modified by hand. DHCP lease information for each recently assigned IP address is automatically stored in the lease database. The information includes the length of the lease, to whom the IP address has been assigned, the start and end dates for the lease, and the MAC address of the network interface card that was used to retrieve the lease. All times in the lease database are in Greenwich Mean Time (GMT), not local time. The lease database is recreated from time to time so that it is not too large. First, all known leases are saved in a temporary lease database. The dhcpd.leases file is renamed dhcpd.leases~ and the temporary lease database is written to dhcpd.leases.
Chapter 24. Dynamic Host Configuration Protocol (DHCP)
The DHCP daemon could be killed or the system could crash after the lease database has been renamed to the backup file but before the new file has been written. If this happens, the dhcpd.leases file does not exist, but it is required to start the service. Do not create a new lease file. If you do, all old leases are lost which causes many problems. The correct solution is to rename the dhcpd.leases~ backup file to dhcpd.leases and then start the daemon.
24.2.3. Starting and Stopping the Server
Important When the DHCP server is started for the first time, it fails unless the dhcpd.leases file exists. Use the command touch /var/lib/dhcp/dhcpd.leases to create the file if it does not exist. If the same server is also running BIND as a DNS server, this step is not necessary, as starting the named service automatically checks for a dhcpd.leases file.
To start the DHCP service, use the command /sbin/service dhcpd start. To stop the DHCP server, use the command /sbin/service dhcpd stop. By default, the DHCP service does not start at boot time. To configure the daemon to start automatically at boot time, refer to Chapter 20 Controlling Access to Services for information on how to manage services. If more than one network interface is attached to the system, but the DHCP server should only be started on one of the interfaces, configure the DHCP server to start only on that device. In /etc/sysconfig/dhcpd, add the name of the interface to the list of DHCPDARGS:
# Command line options here DHCPDARGS=eth0
This is useful for a firewall machine with two network cards. One network card can be configured as a DHCP client to retrieve an IP address to the Internet. The other network card can be used as a DHCP server for the internal network behind the firewall. Specifying only the network card connected to the internal network makes the system more secure because users can not connect to the daemon via the Internet. Other command line options that can be specified in /etc/sysconfig/dhcpd include:
• -p <portnum>
— Specify the UDP port number on which dhcpd should listen. The default is port 67. The DHCP server transmits responses to the DHCP clients at a port number one greater than the UDP port specified. For example, if the default port 67 is used, the server listens on port 67 for requests and responses to the client on port 68. If a port is specified here and the DHCP relay agent is used, the same port on which the DHCP relay agent should listen must be specified. Refer to Section 24.2.4 DHCP Relay Agent for details. — Run the daemon as a foreground process. This is mostly used for debugging. — Log the DHCP server daemon to the standard error descriptor. This is mostly used for debugging. If this is not specified, the log is written to /var/log/messages.
• -f • -d
• -cf <filename>
— Specify the location of the configuration file. The default location is
• -lf <filename> — Specify
the location of the lease database file. If a lease database file already exists, it is very important that the same file be used every time the DHCP server is started. It is strongly recommended that this option only be used for debugging purposes on non-production machines. The default location is /var/lib/dhcp/dhcpd.leases.
• -q
Chapter 24. Dynamic Host Configuration Protocol (DHCP) — Do not print the entire copyright message when starting the daemon.
24.2.4. DHCP Relay Agent
The DHCP Relay Agent (dhcrelay) allows for the relay of DHCP and BOOTP requests from a subnet with no DHCP server on it to one or more DHCP servers on other subnets. When a DHCP client requests information, the DHCP Relay Agent forwards the request to the list of DHCP servers specified when the DHCP Relay Agent is started. When a DHCP server returns a reply, the reply is broadcast or unicast on the network that sent the original request. The DHCP Relay Agent listens for DHCP requests on all interfaces unless the interfaces are specified in /etc/sysconfig/dhcrelay with the INTERFACES directive. To start the DHCP Relay Agent, use the command service dhcrelay start.
24.3. Configuring a DHCP Client
The first step for configuring a DHCP client is to make sure the kernel recognizes the network interface card. Most cards are recognized during the installation process and the system is configured to use the correct kernel module for the card. If a card is added after installation, Kudzu1 should recognize it and prompt for the configuration of the corresponding kernel module for it. Be sure to check the Hardware Compatibility List available at http://hardware.redhat.com/hcl/. If the network card is not configured by the installation program or Kudzu and you know which kernel module to load for it, refer to Chapter 38 Kernel Modules for details on loading kernel modules. To configure a DHCP client manually, modify the /etc/sysconfig/network file to enable networking and the configuration file for each network device in the /etc/sysconfig/network-scripts directory. In this directory, each device should have a configuration file named ifcfg-eth0, where eth0 is the network device name. The /etc/sysconfig/network file should contain the following line:
The NETWORKING variable must be set to yes if you want networking to start at boot time. The /etc/sysconfig/network-scripts/ifcfg-eth0 file should contain the following lines:
DEVICE=eth0 BOOTPROTO=dhcp ONBOOT=yes
A configuration file is needed for each device to be configured to use DHCP. Other options for the network script include:
— Only use this option if the DHCP server requires the client to specify a hostname before receiving an IP address. (The DHCP server daemon in Red Hat Enterprise Linux does not support this feature.) is one of the following:
• PEERDNS=<answer>, where <answer>
Kudzu is a hardware probing tool run at system boot time to determine what hardware has been added or
removed from the system.
as well as a wide variety of values to override. refer to the dhclient and dhclient. no — Non-root users are not allowed to control this device. 24. includes some examples.conf man pages. no — Do not modify /etc/resolv. Installed Documentation • dhcpd man page — Describes how the DHCP daemon works. • • is the specified source IP address for outgoing pack- • USERCTL=<answer>. then yes is the default. README files. .conf.Chapter 24. • /usr/share/doc/dhcp-<version>/ — Contains sample files. amples. or append to client-side configurations. refer to Chapter 18 Network Configuration for details on using the Network Administration Tool to configure a network interface to use DHCP. Additional Resources For configuration options not covered here. aliases. If using DHCP.conf examples. • SRCADDR=<address>. includes some ex- • dhcpd. prepend. Tip For advanced configurations of client DHCP options such as protocol timing.conf. includes some man page — Explains how to configure the DHCP leases file. man page — Explains the DHCP Relay Agent and its configuration options.4. where <answer> is one of the following: yes — Non-root users are allowed to control this device. dynamic DNS support.conf with information from the server. If you prefer using a graphical interface.1. refer to the following resources. 24. • dhcpd. Dynamic Host Configuration Protocol (DHCP) • • 193 yes — Modify /etc/resolv. man page — Explains how to configure the DHCP configuration file. and release notes for the specific version of the DHCP service. lease requirements and requests. where <address> ets.leases • dhcp-options • dhcrelay man page — Explains the syntax for declaring DHCP options in dhcpd.4.
194 Chapter 24. Dynamic Host Configuration Protocol (DHCP) .
4. Configure the basic settings under the Main tab. logging attributes. add any additional virtual hosts. If additional modules are installed. If you want to migrate an existing configuration file by hand. It does not use the old srm. Only modules provided with Red Hat Enterprise Linux can be configured with the HTTP Configuration Tool.conf configuration file by hand if you wish to use this tool.0.0 of the Apache HTTP Server. Click on the Virtual Hosts tab and configure the default settings. Exit the application and select to save your settings. To start the application. Configure the connections settings under the Performance Tuning tab. To serve more than one URL or virtual host. in an XTerm or GNOME Terminal). leave them empty. configure the Default Virtual Host.Chapter 25.conf configuration files. Caution Do not edit the /etc/httpd/conf/httpd. Configure the server settings under the Server tab. If you want to add additional modules or configuration options that are not available in HTTP Configuration Tool.conf or access. go to the Main Menu Button => System Settings => Server Settings => HTTP or type the command system-config-httpd at a shell prompt (for example. 6. you can use the HTTP Configuration Tool to migrate the configuration file to the new format for version 2. Start the HTTP Configuration Tool. you cannot use this tool. Copy all necessary files to the DocumentRoot and cgi-bin directories. The general steps for configuring the Apache HTTP Server using the HTTP Configuration Tool are as follows: 1. . 3. It also requires the X Window System and root access. and maximum number of connections. The HTTP Configuration Tool generates this file after you save your changes and exit the program. If you configured the Apache HTTP Server with the HTTP Configuration Tool in previous versions of Red Hat Enterprise Linux and then performed an upgrade. you can configure directives such as virtual hosts. Through the graphical interface. The configuration file saved will be compatible with version 2. Under the Virtual Hosts tab. Apache HTTP Server Configuration Red Hat Enterprise Linux provides version 2. and save it. refer to the migration guide at /usr/share/doc/httpd-<ver>/migration. 8.0. 2. make any changes to the configuration.html or the Red Hat Enterprise Linux Reference Guide for details. 7. The HTTP Configuration Tool allows you to configure the /etc/httpd/conf/httpd. 5. The httpd and system-config-httpd RPM packages need to be installed to use the HTTP Configuration Tool. they can not be configured using this tool.conf configuration file for the Apache HTTP Server.
the Web server attempts to resolve it from the IP address of the system. This option corresponds to the ServerName directive in httpd. you might set the server name to www.196 Chapter 25. The server name does not have to be the domain name resolved from the IP address of the server. For port 1024 and above. . this email address is used so that users can report a problem to the server's administrator. Basic Settings Use the Main tab to configure the basic server settings. Basic Settings Enter a fully qualified domain name that you have the right to use in the Server Name text area. Refer to http://httpd.1.0/dnscaveats. select it and click the Delete button. Tip If you set the server to listen to a port under 1024.org/docs-2. you must be root to start it. This option corresponds to the ServerAdmin directive in httpd. Clicking the Edit button in the Available Addresses frame shows the same window as the Add button except with the fields populated for the selected entry. httpd can be started as a regular user. create an entry for each IP address. Either choose the Listen to all addresses option to listen to all IP addresses on the defined port or specify a particular IP address over which the server accepts connections in the Address field. use an IP address instead of a domain name to prevent a DNS lookup failure.com.conf. Entering an asterisk (*) in the Address field is the same as choosing Listen to all addresses. Enter the email address of the person who maintains the Web server in the Webmaster email address text area. By default. Click the Add button to define additional ports on which to accept requests. If at all possible.conf. It is used when creating redirection URLs. Use the Available Addresses area to define the ports on which the server accepts incoming requests. Red Hat configures the Apache HTTP Server to listen to port 80 for non-secure Web communications.html for more information about Issues Regarding DNS and Apache. The ServerName directive sets the hostname of the Web server. To specify more than one IP address with the same port number. If you configure the server's error pages to contain an email address.example.example. Apache HTTP Server Configuration 25.conf.apache. For example. This option corresponds to the Listen directive in httpd. To delete an entry. Figure 25-1.com while the server's real DNS name is foo. If you do not define a server name. Only specify one IP address per port number. A window as shown in Figure 25-2 appears. The default value is root@localhost.
Apache HTTP Server Configuration 197 Figure 25-2. If you add a virtual host. Default Settings After defining the Server Name. Site Configuration The default values for the Directory Page Search List and Error Pages work for most servers.2.Chapter 25. click the Virtual Hosts tab and click the Edit Default Settings button. Figure 25-3. 25. A window as shown in Figure 25-3 appears. the settings you configure for the virtual host take precedence for that virtual host. Webmaster email address. the default value is used. Configure the default settings for your Web server in this window. and Available Addresses.1. If you are unsure of these settings. For a directive not defined within the virtual host settings. do not modify them. Site Configuration . Available Addresses 25.2.
Choose Default to display the default short error message.1 General Options for information about configuring the ServerAdmin directive. Show footer — Display just the default footer at the bottom of error pages. to redirect a 404 Not Found error code to a webpage that you created in a file called 404. The DirectoryIndex is the default page served by the server when a user requests an index of a directory by specifying a forward slash (/) at the end of the directory name. copy 404. including the http://. Choose URL to redirect the client to an external URL and enter a complete URL. in the Location field. select the error code and click the Edit button.3. From the Default Error Page Footer menu.html. In this case.Not Found error code and enter /error/404. or a server-generated directory list.2. the default action is to display the short error message shown in the Error Code column. Logging Use the Logging tab to configure options for specific transfer and error logs. you can choose one of the following options: • Show footer with email address — Display the default footer at the bottom of all error pages along with the email address of the website maintainer specified by the ServerAdmin directive. The server tries to find one of the files listed in the DirectoryIndex directive and returns the first one it finds. DocumentRoot is the Document Root directory that you have defined (the default is /var/www/html/). The location must begin the a slash (/) and be relative to the Document Root. Use the Error Code section to configure Apache HTTP Server to redirect the client to a local or external URL in the event of a problem or error.html as the Location.com/this_directory/. they are going to get either the DirectoryIndex page. This option corresponds to the ErrorDocument directive.example. If it does not find any of these files and if Options Indexes is set for that directory. Apache HTTP Server Configuration The entries listed in the Directory Page Search List define the DirectoryIndex directive. If a problem or error occurs when a client tries to connect to the Apache HTTP Server. If the Document Root is left as the default location. It records the IP address of the client that is attempting to connect. By default. if it exists. . Choose File to redirect the client to an internal URL and enter a file location under the document root for the Web server. The transfer log contains a list of all attempts to access the Web server. If the path and file name do not start with a slash (/). Enter the name of the path and file in which to store this information.1..html. For example. For example. To override this default configuration. the server generates and returns a list. the file should be copied to /var/www/error/404./error/404.html to DocumentRoot/. This option corresponds to the TransferLog directive. in HTML format. choose File as the Behavior for 404 . when a user requests the page http://www. Then. • • 25.2. the server writes the transfer log to the /var/log/httpd/access_log file and the error log to the /var/log/httpd/error_log file. Refer to Section 25. No footer — Do not display a footer at the bottom of error pages.html. and the file on the Web server that it is trying to retrieve. the path is relative to the server root directory as configured.198 Chapter 25. the date and time of the attempt. of the subdirectories and files in the directory.
At least one of the IP addresses in the forward lookup must match the address from the first reverse lookup. Choosing Reverse Lookup sets the value to on. for your own Web server's . This option corresponds to the LogLevel directive. This option corresponds to the ErrorLog directive. Therefore. Logging You can configure a custom log format by checking Use custom logging facilities and entering a custom log string in the Custom Log String field. If you choose Reverse Lookup. It can be set (from least verbose to most verbose) to emerg. Choosing No Reverse Lookup sets the value to off. Each individual connection made to look up each hostname adds up. the path is relative to the server root directory as configured. If you choose Double Reverse Lookup.org/docs-2. Apache HTTP Server Configuration 199 Figure 25-4. If the path and file name do not start with a slash (/). Generally.html#formats for details on the format of this directive. alert. This configures the LogFormat directive. error. Reverse lookups and double reverse lookups are also an issue for the Internet as a whole. Use the Log Level menu to set the verbosity of the error messages in the error logs. your server performs a double-reverse DNS. your server automatically resolves the IP address for each connection which requests a document from your Web server. warn. because the DNS requests add a load to your server and may slow it down. notice. The value chosen with the Reverse DNS Lookup menu defines the HostnameLookups directive. If your server is busy. the effects of trying to perform these reverse lookups or double reverse lookups may be quite noticeable.Chapter 25. after a reverse lookup is performed. Resolving the IP address means that your server makes one or more connections to the DNS in order to find out the hostname that corresponds to a particular IP address. Enter the name of the path and file in which to store this information.apache.0/mod/mod_log_config. In other words. you should leave this option set to No Reverse Lookup. The error log contains a list of any server errors that occur. info or debug. Refer to http://httpd. Choosing Double Reverse Lookup sets the value to double. a forward lookup is performed on the result. crit.
Use the Environment Variables page to configure the directives for this module. pass. Click Add in the Unset for CGI Scripts section. Apache HTTP Server Configuration benefit. The Set for CGI Scripts section configures the SetEnv directive.3. or unset for CGI scripts. type the command env at a shell prompt. Environment Variables Use the Environment tab to configure options for specific variables to set. To see this environment variable. The Apache HTTP Server can use the mod_env module to configure the environment variables which are passed to CGI scripts and SSI pages. and enter the . you should leave this option set to No Reverse Lookup. Click OK to add it to the list.200 Chapter 25. Sometimes it is necessary to modify environment variables for CGI scripts or server-side include (SSI) pages. The Pass to CGI Scripts section configures the PassEnv directive. click the Add button inside the Set for CGI Script section. For example. Environment Variables To remove an environment variable so that the value is not passed to CGI scripts and SSI pages. Use the Pass to CGI Scripts section to pass the value of an environment variable when the server is first started to CGI scripts. use the Unset for CGI Scripts section. Use the Set for CGI Scripts section to set an environment variable that is passed to CGI scripts and SSI pages. and type MAXNUM in the Environment Variable text field and 50 in the Value to set text field. Figure 25-5. as shown in Figure 25-5.2. Click the Add button inside the Pass to CGI Scripts section and enter the name of the environment variable in the resulting dialog box. to set the environment variable MAXNUM to 50. as well as for the Internet's benefit. Click OK to add it to the list. 25.
To learn more about environment variables in the Apache HTTP Server. select it from the list and click the corresponding Edit button. select it and click the corresponding Delete button. Includes — Allow server-side includes. Directories Use the Directories page in the Performance tab to configure options for specific directories. To edit any of these environment values. Apache HTTP Server Configuration 201 name of the environment variable to unset.html 25.Chapter 25. This corresponds to the UnsetEnv directive. You can configure the following options: • • • ExecCGI — Allow execution of CGI scripts. FollowSymLinks — Allow symbolic links to be followed. This corresponds to the <Directory> directive.4. . Click OK to add it to the list. CGI scripts are not executed if this option is not chosen. Figure 25-6. refer to the following: http://httpd. Directories Click the Edit button in the top right-hand corner to configure the Default Directory Options for all directories that are not specified in the Directory list below it.2.apache. To delete any entry from the list. The options that you choose are listed as the Options directive within the <Directory> directive.org/docs-2.0/env.
you can specify one of the following: • • • • • Allow all hosts — Type all to allow access to all hosts.202 • • • • Chapter 25. this option is disabled by default. The Order directive controls the order in which allow and deny directives are evaluated.168.0. if no DirectoryIndex (such as index. Indexes — Display a formatted list of the directory's contents. A subnet — Such as 192. SymLinksIfOwnerMatch — Only follow symbolic links if the target file or directory has the same owner as the link. but disable the #exec and #include commands in CGI scripts.255. click the Add button beside the Directory list box.0/255.1. Apache HTTP Server Configuration IncludesNOEXEC — Allow server-side includes.0/16 Figure 25-7. To specify options for specific directories. A window as shown in Figure 25-7 appears. Enter the directory to configure in the Directory text field at the bottom of the window.255. In the Allow hosts from and Deny hosts from text field.htaccess files override directory options. Full IP address — Allow access to a specific IP address. Multiview — Support content-negotiated multiviews.htaccess file take precedence.html) exists in the requested directory. the configuration directives in the . If you check the Let .3.0 A network CIDR specification — such as 10. Partial domain name — Allow all hosts whose names match or end with the specified string. Select the options in the right-hand list and configure the Order directive with the left-hand side options. Directory Settings .
Figure 25-8.com and http://www. you can run the website for http://www. You can also edit a virtual host by selecting it and clicking the Edit button. Set the name of the virtual host in the Virtual Host Name text area.3. click the Virtual Hosts tab and then click the Add button. General Options The General Options settings only apply to the virtual host that you are configuring. This email address is used in the footer of error pages if you choose to show a footer with an email address on the error pages. . Adding and Editing a Virtual Host To add a virtual host. 25. Set the Document Root Directory value to the directory that contains the root document (such as index. Apache HTTP Server Configuration 203 25.com on the same Web server using virtual hosts.1. For example.3. This option corresponds to the DocumentRoot directive within the <VirtualHost> directive. Virtual Hosts Settings Virtual hosts allow you to run different servers for different IP addresses. If a directive is set server-wide using the Edit Default Settings button and not defined within the virtual host settings. different host names. The default DocumentRoot is /var/www/html.1. This option corresponds to the <VirtualHost> directive for the default virtual host and IP based virtual hosts. the default setting is used.1.org/docs-2.html) for the virtual host. The directives set for a virtual host only apply to that particular virtual host. you can define a Webmaster email address in the Main tab and not define individual email addresses for each virtual host. The Webmaster email address corresponds to the ServerAdmin directive within the VirtualHost directive.Chapter 25.3. The HTTP Configuration Tool includes a default virtual host as shown in Figure 25-8. or different ports on the same machine.example.anotherexample.apache. 25. This name is used by HTTP Configuration Tool to distinguish between virtual hosts. It corresponds to the <NameVirtualHost> directive for a name based virtual host. Virtual Hosts http://httpd.0/vhosts/ and the Apache HTTP Server documentation on your machine provide more information about virtual hosts. For example.
Apache HTTP Server Configuration In the Host Information section.204 Chapter 25. IP based Virtual Host If you choose IP based Virtual Host.2. IP based Virtual Host. Specify the host name for the virtual host in the Server Host Name field. the main server settings are used. If there is no default virtual host defined. SSL Note You cannot use name based virtual hosts with SSL because the SSL handshake (when the browser accepts the secure Web server's certificate) occurs before the HTTP request. If you plan to use name-based virtual hosts. asterisk" (:*) to configure all ports for the IP address. . choose Default Virtual Host. Name based Virtual Host If you choose Name based Virtual Host. In the Aliases section. To specify a port. Use "colon. Specify this IP address in the IP address field. a window appears to configure the NameVirtualHost directive based on the host name of the server. use the syntax IP Address:Port. Specify the IP address in the IP address field. Specify the host name for the virtual host in the Server Host Name field. The default virtual host settings are used when the requested IP address is not explicitly listed in another virtual host. 25. To specify multiple IP addresses. or Name based Virtual Host. Adding an alias here adds a ServerAlias directive within the NameVirtualHost directive.1. separate each IP address with spaces. asterisk" (:*) to configure all ports for the IP address. Use "colon. use the syntax IP Address:Port. a window appears to configure the <VirtualHost> directive based on the IP address of the server. click Add to add a host name alias.3. remember that they only work with your non-secure Web server. which identifies the appropriate name based virtual host. To specify a port. To specify multiple IP addresses. Default Virtual Host You should only configure one default virtual host (remember that there is one setup by default). separate each IP address with spaces.
However. SSL Support If an Apache HTTP Server is not configured with SSL support.3. . Enabling Apache SSL support enables the use of the mod_ssl security module. click the Edit button. Refer to Section 25. For example. To enable it through the HTTP Configuration Tool. 25. and Directories options for the virtual hosts are the same directives that you set when you clicked the Edit Default Settings button.Chapter 25. an open source website that distributes open source software and documentation has no need for secure communications. you must allow access through port 443 under the Main tab => Available Addresses. communications between an Apache HTTP Server and its clients are not encrypted. and check the Enable SSL Support option as shown in Figure 25-9. The SSL Configuration section is preconfigured with the dummy digital certificate. refer to the Chapter 26 Apache HTTP Secure Server Configuration. Refer to Section 25.1.2 Default Settings for details on these options. choose SSL from the left-hand menu. Apache HTTP Server Configuration 205 Figure 25-9. an ecommerce website that requires credit card information should use the Apache SSL support to encrypt its communications. For details on purchasing a CA-approved digital certificate. The digital certificate provides authentication for your secure Web server and identifies the secure server to client Web browsers. Do not use the dummy one provided for your website.3. Then. select the virtual host name in the Virtual Hosts tab. You must purchase your own digital certificate.1 Basic Settings for details. Environment Variables. This is appropriate for websites without personal or confidential information. Additional Virtual Host Options The Site Configuration. except the options set here are for the individual virtual hosts that you are configuring.
206 Chapter 25. The user should only have privileges so that it can access files which are supposed to be visible to the outside world. however. The default value is the ServerRoot. Once the server has attached itself to its port. The Apache HTTP Server tries to switch to this directory before executing a core dump. The default for User is apache. The Core Dump Directory value corresponds to the CoreDumpDirectory directive. This directive sets the path to the lockfile used when the server is compiled with either USE_FCNTL_SERIALIZED_ACCEPT or USE_FLOCK_SERIALIZED_ACCEPT. the core dump can not be written.4. Server Configuration The Lock File value corresponds to the LockFile directive. . so they can not be used by anyone but root. it should be left to the default value. This directive sets the file in which the server records its process ID (pid). Warning Unless you know exactly what you are doing. it hands the process off to the apache user before it accepts any connection requests. if the user that the server runs as can not write to this directory. Using root as the User creates large security holes for your Web server. It should be left to the default value unless the logs directory is located on an NFS share. This file should only be readable by root. the default value should be changed to a location on the local disk and to a directory that is readable only by root. do not set the User directive to root. Ports below 1024 are reserved for system use. It must be stored on the local disk. However. Any files inaccessible to this user are also inaccessible to your website's visitors. The parent httpd process first runs as root during normal operations. The default settings for these options are appropriate for most situations. Server Settings The Server tab allows you to configure basic server settings. This user's settings determine the server's access. Change this value to a directory writable by the user the server runs as. In most cases. The user is also the owner of any CGI processes spawned by the server. but is then immediately handed off to the apache user. The User value corresponds to the User directive. Figure 25-10. The PID File value corresponds to the PidFile directive. If this is the case. Apache HTTP Server Configuration 25. It sets the userid used by the server to answer requests. The user should not be allowed to execute any code which is not intended to be in response to HTTP requests. if you want to write the core dumps to disk for debugging purposes. The server must start as root because it needs to bind to a port below 1024.
Group sets the group under which the server answers requests. the KeepAlive directive is set to true. If you uncheck the Allow Persistent Connections option. The default settings for these options are appropriate for most situations. The default value is 100. Apache HTTP Server Configuration 207 The Group value corresponds to the Group directive. This directive sets the number of seconds your server waits for a subsequent request. Once a request has been received. . After this maximum number of processes is reached. the amount of time that your server waits for receipts and transmissions during communications. Connection Timeout defines. Performance Tuning Set Max Number of Connections to the maximum number of simultaneous client requests that the server can handle. Altering these settings may affect the overall performance of your Web server. Performance Tuning Click on the Performance Tuning tab to configure the maximum number of child server processes you want and to configure the Apache HTTP Server options for client connections. and how long it waits between ACKs responding to TCP packets. Connection Timeout is set to 300 seconds. in seconds.5. no one else can connect to the Web server until a child server process is freed. If you check the Allow unlimited requests per connection option. This option corresponds to the MaxRequestsPerChild directive. Setting the Persistent Connections to a high value may cause the server to slow down. the KeepAlive directive is set to false. The Group directive is similar to the User directive. By default. after a request has been served. 25. the MaxKeepAliveRequests directive is set to 0 and unlimited requests are allowed. and the KeepAliveTimeout directive is set to the number that is selected as the Timeout for next Connection value. For each connection. the Connection Timeout value applies instead. which should be appropriate for most situations. The default group is also apache. before it closes the connection. Connection Timeout defines how long your server waits to receive a GET request. Figure 25-11. Set the Max requests per connection to the maximum number of requests allowed per persistent connection. a child httpd process is created. This option corresponds to the MaxClients directive. This option corresponds to the TimeOut directive. You can not set this value to higher than 256 without recompiling. the more server processes are waiting for another connection from the last client that connected to it. which is appropriate for most situations. Specifically. how long it waits to receive TCP packets on a POST or PUT request. If you check it. depending on how many users are trying to connect to it.Chapter 25. The higher the number.
Installed Documentation • /usr/share/docs/httpd-<version>/migration.apache.conf configuration file has been manually modified.0. Related Books • • Apache: The Definitive Guide by Ben Laurie and Peter Laurie.6. 25. refer to the following resources.0 as well as information about how to migration the configuration file manually. A dialog window appears.html — The Apache Centralized Knowledgebase compiled by Red Hat.7. Useful Websites • • • • http://www. If you click Yes to confirm this choice. You are prompted to confirm this decision.html — Red Hat Support maintains a list of useful Apache HTTP Server links. http://www.html — The Apache Migration HOWTO document contains a list of changes from version 1.org/ — The Apache Software Foundation. Red Hat Enterprise Linux Reference Guide. click the OK button in the bottom right corner of the HTTP Configuration Tool window.redhat.0 User's Guide.redhat.2. Important After saving your settings. Remember that your original configuration file is overwritten with your new settings.0/ — The Apache Software Foundation's documentation on Apache HTTP Server version 2.bak. you must restart the httpd daemon with the command service httpd restart.208 Chapter 25.1.org/docs-2.3. If the HTTP Configuration Tool detects that the httpd.conf. Red Hat.3 to Apache HTTP Server version .3 to version 2. 25. 25. it saves the manually modified file as /etc/httpd/conf/httpd.apache. click the Cancel button in the bottom right corner of the HTTP Configuration Tool window. Inc. — This companion manual includes instructions for migrating from Apache HTTP Server version 1.com/support/resources/web_ftp/apache. If you want to save your Apache HTTP Server configuration settings. You must be logged in as root to execute this command.7. http://www. If this is the first time that you have used the HTTP Configuration Tool. O'Reilly & Associates. Apache HTTP Server Configuration 25. Additional Resources To learn more about the Apache HTTP Server. Inc. your settings are not saved. http://httpd. including the Apache HTTP Server Version 2. If you answer Yes.7.7. warning you that the configuration file has been manually modified. 25.com/support/docs/faqs/RH-apache-FAQ/book1. Saving Your Settings If you do not want to save your Apache HTTP Server configuration settings. a dialog window appears.conf. your settings are saved in /etc/httpd/conf/httpd.
more details about the Apache HTTP Server directives. Apache HTTP Server Configuration 209 2.Chapter 25. and instructions for adding modules to the Apache HTTP Server.0 manually. .
210 Chapter 25. Apache HTTP Server Configuration .
mod_ssl The mod_ssl package includes the mod_ssl module.conf. openssl The openssl package contains the OpenSSL toolkit. The mod_ssl module is a security module for the Apache HTTP Server. In contrast. When possible. Apache HTTP Server modules. this guide points to appropriate places where you can find more in-depth documentation on particular subjects. An Overview of Security-Related Packages To enable the secure server. which provides strong cryptography for the Apache HTTP Server via the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols. 26.d/ssl. regular HTTP communications between a browser and a Web server are sent in plain text. and other files used by the Apache HTTP Server. The OpenSSL toolkit implements the SSL and TLS protocols. This chapter is not meant to be complete and exclusive documentation for any of these programs. and hence for mod_ssl to work. configuration files. The mod_ssl configuration file is located at /etc/httpd/conf.1.d/*. man pages. how to generate your own self-signed certificate. You can also learn the steps necessary to generate a private key and a certificate request. This chapter shows you how to install these programs. Introduction This chapter provides basic information on the Apache HTTP Server with the mod_ssl security module enabled to use the OpenSSL library and toolkit. The mod_ssl module uses the tools provided by the OpenSSL Project to add a very important feature to the Apache HTTP Server — the ability to encrypt communications. you must have the following packages installed at a minimum: httpd The httpd package contains the httpd daemon and related utilities. This statement is included by default in the default Apache HTTP Server configuration file.conf file. and also includes a general purpose cryptography library.conf in the /etc/httpd/conf/httpd.Chapter 26. Apache HTTP Secure Server Configuration 26. and how to install a certificate to use with your secure server. The combination of these three components are referred to in this chapter as the secure Web server or just as the secure server. For this file to be loaded.2. you must have the statement Include conf. icons. Additionally. other software packages provide certain security functionalities (but are not required by the secure server to function): . which could be intercepted and read by someone along the route between the browser and the server.
you should install this package. and the APXS utility. OpenSSH packages The OpenSSH packages provide the OpenSSH set of network connectivity tools for logging into and executing commands on a remote machine.openssh. while the native support in OpenLDAP's slapd can also handle in-band upgrades for using encryption in response to a StartTLS client request. and other attacks on the communications between your machine and the remote machine. The secure shell daemon is the server side of the OpenSSH suite and must be installed on your host to allow SSH clients to connect to your host. including the following: ssh. The openssh-askpass-gnome package can be used in conjunction with the GNOME desktop environment to display a graphical dialog window when OpenSSH programs prompt for a password. If you are running GNOME and using OpenSSH utilities. a secure replacement for rcp (for securely copying files between machines). and the OpenSSH website at http://www. The openssh package also contains scp. you do not need to install this package. The openssh-server package contains the sshd secure shell daemon and related files. For example. The openssh-askpass package supports the display of a dialog window which prompts for a password during use of the OpenSSH agent. You need to install this package only if you are developing applications which include SSL support — you do not need this package to use SSL. connection hijacking. Refer to the Red Hat Enterprise Linux Reference Guide for more information on loading modules onto your secure server using Apache's dynamic shared object (DSO) functionality. a secure replacement for rlogin (for remote login) and telnet (for communicating with another host via the Telnet protocol). Note Newer implementations of various daemons now provide their services natively over SSL.com/. and slogin. such as dovecot or OpenLDAP's slapd server. Stunnel supports the SSL encryption of TCP connections. so you can avoid eavesdropping. sftp. Apache HTTP Secure Server Configuration The httpd-devel package contains the Apache HTTP Server include files. and LDAP) without requiring any changes to the daemon's code. OpenSSH tools encrypt all traffic (including passwords). the Red Hat Enterprise Linux Reference Guide. . It provides encryption for non-SSL aware daemons and protocols (such as POP. other than the modules provided with this product. If you do not intend to load other modules onto your Apache HTTP Server. a secure replacement for rsh. which may be more desirable than using stunnel. You need all of these if you intend to load any extra modules. For more information about OpenSSH. see Chapter 21 OpenSSH. header files. stunnel The stunnel package provides the Stunnel SSL wrapper.212 httpd-devel Chapter 26. The openssh-clients package contains the client programs needed to make encrypted connections to SSH servers. The openssh package includes core files needed by both the OpenSSH client programs and the OpenSSH server. openssl-devel The openssl-devel package contains the static libraries and the include file needed to compile applications with support for various cryptographic algorithms and protocols. use of stunnel only provides wrapping of protocols. IMAP. a secure replacement for ftp (for transferring files between machines).
which they use to decode each other's transmissions. A person or an organization keeps their private key a secret and publishes their public key. use public cryptography to create a public and private key pair. the https:// prefix is used at the beginning of the Uniform Resource Locator (URL) in the navigation bar. A secure server uses a certificate to identify itself to Web browsers. you send your certificate request (including your public key). Self-signed certificates are not automatically accepted by a user's browser — users are prompted by the browser to accept the certificate and . both ends of the transaction have the same key. and then sends back a certificate for your secure server. The CA-approved digital certificate provides authentication for your secure server (the CA puts its reputation behind its certification of your organization's identity). data encoded with the private key can only be decoded with the public key. An Overview of Certificates and Security Your secure server provides security using a combination of the Secure Sockets Layer (SSL) protocol and (in most cases) a digital certificate from a Certificate Authority (CA). proof of your company's identity. Apache HTTP Secure Server Configuration 213 Table 26-1 displays a summary of the secure server packages and whether each package is optional for the installation of a secure server.Chapter 26. that self-signed certificates should not be used in most production environments. To set up your secure server. Package Name httpd mod_ssl openssl httpd-devel openssh openssh-askpass openssh-askpass-gnome openssh-clients openssh-server openssl-devel stunnel Optional? no no no yes yes yes yes yes yes yes yes Table 26-1. A certificate from a reputable CA guarantees that a website is associated with a particular company or organization. In conventional or symmetric cryptography. In public or asymmetric cryptography. and payment to a CA. or you can get a certificate from a CA. however. you can create your own self-signed certificate. SSL handles the encrypted communications as well as the mutual authentication between browsers and your secure server. Note. Alternatively. Data encoded with the public key can only be decoded with the private key.3. Security Packages 26. In most cases. Encryption depends upon the use of keys (think of them as secret encoder/decoder rings in data format). two keys co-exist: a public key and a private key. The CA verifies the certificate request and your identity. You can generate your own certificate (called a "self-signed" certificate). When your browser is communicating using SSL encryption.
Refer to Section 26. you are not be allowed to because VeriSign issues certificates for one specific server software and IP address/domain name combination.5 Types of Certificates for more information on the differences between self-signed and CA-signed certificates. The following two situations provide instances where you are not able to use your existing key and certificate: • If you are changing your IP address or domain name — Certificates are issued for a particular IP address and domain name pair.4.key /etc/httpd/conf/ssl. • If you have an existing key and certificate that you can use. you do not have to generate a new key and obtain a new certificate. the VeriSign certificate you obtained to use with the previous configuration will not work with the new configuration.crt Then. 26. start your secure server with the command: /sbin/service httpd start You are prompted to enter your passphrase.key) and certificate (httpsd.key/server. However. Move your existing key file to: /etc/httpd/conf/ssl.key Move your existing certificate file to: /etc/httpd/conf/ssl. Apache HTTP Secure Server Configuration create the secure connection. skip to Section 26. Once you have a self-signed certificate or a signed certificate from the CA of your choice.214 Chapter 26.crt /etc/httpd/conf/ssl. Use the following two commands to move and rename your key and certificate files: mv /etc/httpd/conf/httpsd.crt/server. you must install it on your secure server. You must obtain a new certificate.crt) are located in /etc/httpd/conf/. If you are upgrading from the Red Hat Secure Web Server.key/server. If you already have a VeriSign certificate for another purpose.crt After you have moved your key and certificate. the server starts. Using Pre-Existing Keys and Certificates If you already have an existing key and certificate (for example. you may need to move and rename the files which contain your key and certificate. You must get a new certificate if you are changing your IP address or domain name. your old key ( httpsd. If you have a certificate from VeriSign and you are changing your server software — VeriSign is a widely used CA. Move and rename your key and certificate so that the secure server can use them. you can probably use your existing key and certificate with the secure server.9 Testing The Certificate.crt/server.key mv /etc/httpd/conf/httpsd. If you change either of those parameters (for example. . However. if you are installing the secure server to replace another company's secure server product). you may have been considering using your existing VeriSign certificate with your new secure server. if you previously used a different secure server product). After you type it in and press [Enter].
to a CA. Red Hat does not make recommendations on which certificate authority to choose. 5. 2. a CA-signed certificate is recommended. A quick overview is as follows: 1. The certificate request contains information about your server and the company hosting it. You can generate a self-signed certificate for your secure server. If your secure server is being accessed by the public at large. If a browser encounters a certificate whose authorizing CA is not in the list. Your decision may be based on your past experiences. Most Web browsers that support SSL have a list of CAs whose certificates they automatically accept.6. A self-signed certificate is not automatically recognized by most Web browsers and does not provide any guarantee concerning the identity of the organization that is providing the website. you need to follow the instructions they provide on how to obtain a certificate from them.Chapter 26. If your secure server is to be used in a production environment. without prompting the user. a CA verifies that the organization requesting the certificate was actually who they claimed to be. or purely on monetary factors. Generating a Key You must be root to generate a key. your secure server needs a certificate signed by a CA so that people who visit your website know that the website is owned by the organization who claims to own it. the first step is to generate a key. Install this certificate on your secure server and begin handling secure transactions. When a CA issues a signed certificate. Apache HTTP Secure Server Configuration 215 26. they provide you with a digital certificate. Types of Certificates If you installed your secure server from the RPM package provided by Red Hat. along with documents proving your identity. Whether you are getting a certificate from a CA or generating your own self-signed certificate. but be aware that a self-signed certificate does not provide the same functionality as a CA-signed certificate. they are guaranteeing the identity of the organization that is providing the webpages to the browser. Create a certificate request based on the public key. When the CA is satisfied that you are indeed who you claim to be. the browser asks the user to either accept or decline the connection. Once you have decided upon a CA. Send the certificate request. a random key and a test certificate are generated and put into the appropriate directories. on the experiences of your friends or colleagues. What are the differences between the two? A CA-signed certificate provides two important capabilities for your server: • • Browsers (usually) automatically recognize the certificate and allow a secure connection to be made. you must generate your own key and obtain a certificate which correctly identifies your server. Create an encryption private and public key pair. however. A CA-signed certificate provides both of these important capabilities for a secure server. The process of getting a certificate from a CA is fairly easy. 4.5. You need a key and a certificate to operate your secure server — which means that you can either generate a self-signed certificate or purchase a CA-signed certificate from a CA. Before signing a certificate. . Refer to Section 26. Before you begin using your secure server. 26.6 Generating a Key for instructions. 3.
Use the following command to create your key: /usr/bin/openssl genrsa 1024 > /etc/httpd/conf/ssl......key Generating RSA private key.... Change to the /usr/share/ssl/certs/ directory and type in the following command: make genkey Your system displays a message similar to the following: umask 77 .key/server.. the key must be completely re-generated..... If you forget this passphrase. Remove the fake key and certificate that were generated during the installation with the following commands: rm ssl.... is created.... Re-type the passphrase to verify that it is correct.++++++ ...... use the following command to make sure the permissions are set correctly for the file: chmod go-rwx /etc/httpd/conf/ssl....... For security reason. . Note that if you do not want to type in a passphrase every time you start your secure server.. Note You are required to remember and enter this passphrase every time you start your secure server... Also.. It is not recommended that you disable the passphrase feature for secure server. it should contain at least eight characters.. create your own random key..... 1024 bit long modulus .key/server. you must use the following two commands instead of make genkey to create the key. remember that your passphrase is case sensitive....++++++ e is 65537 (0x10001) Enter pass phrase: You now must enter in a passphrase..... include numbers and/or punctuation.key Then.. Apache HTTP Secure Server Configuration First..crt/server.crt Next. and it should not be a word in a dictionary. \ /usr/bin/openssl genrsa -des3 1024 > /etc/httpd/conf/ssl.key... the file containing your key.. Caution Disabling the passphrase feature for your secure server is a security risk.key/server..216 Chapter 26.....key After you use the above commands to create your key. you do not need to use a passphrase to start your secure server.... Once you have typed it in correctly.... use the cd command to change to the /etc/httpd/conf/ directory......key rm ssl... /etc/httpd/conf/ssl.key/server.key/server.
Apache HTTP Secure Server Configuration 217 Problems associated with not using a passphrase are directly related to the security maintained on the host machine. Make a backup copy of this file and keep the backup copy in a safe. section) []:Testing . that person could obtain your private key (the contents of your server. the extra security provided by entering a passphrase is a worthwhile effort in most cases. The key could be used to serve webpages that appear to be from your secure server. Generating a Certificate Request to Send to a CA Once you have created a key.csr/server. Make sure you are in the /usr/share/ssl/certs/ directory. Next. ----Country Name (2 letter code) [GB]:US State or Province Name (full name) [Berkshire]:North Carolina Locality Name (eg. What you are about to enter is what is called a Distinguished Name or a DN. If UNIX security practices are rigorously maintained on the host computer (all operating system patches and updates are installed as soon as they are available. secure server's passphrase may seem unnecessary. However. 26. city) [Newbury]:Raleigh Organization Name (eg.Chapter 26. no unnecessary or risky services are operating. since your secure server should not need to be re-booted very often. and so on). the field will be left blank. The server.key/server. continue to Section 26. For example.key file should be owned by the root user on your system and should not be accessible to any other user.csr Using configuration from /usr/share/ssl/openssl. looks similar to the following: You are about to be asked to enter information that will be incorporated into your certificate request.key file). Your only option is to request (and pay for) a new certificate. If you enter '.key -out /etc/httpd/conf/ssl. \ /usr/bin/openssl req -new -key /etc/httpd/conf/ssl. your system displays some instructions and then ask for a series of responses from you. You need the backup copy because if you ever lose the server.'. Your inputs are incorporated into the certificate request. There are quite a few fields but you can leave some blank For some fields there will be a default value. If you are generating your own self-signed certificate.cnf Enter pass phrase: Type in the passphrase that you chose when you were generating your key unless you don't need to. continue to Section 26.7 Generating a Certificate Request to Send to a CA. The display.7. your certificate no longer works and the CA is not able to help you. if an unscrupulous individual compromises the regular UNIX security on the host machine. If you are going to purchase a certificate from a CA.key file after using it to create your certificate request. secure place. and type the following command: make certreq Your system displays the following output and asks you for your passphrase (unless you disabled the passphrase option): umask 77 . with example responses. the next step is to generate a certificate request which you need to send to the CA of your choice. company) [My Company Ltd]:Test Company Organizational Unit Name (eg.8 Creating a Self-Signed Certificate.
com Please enter the following 'extra' attributes to be sent with your certificate request A challenge password []: An optional company name []: The default answers appear in brackets ([]) immediately after each request for input." Do not use either of the extra attributes (A challenge password and An optional company name). The Email Address should be the email address for the webmaster or system administrator. Accept the default by pressing [Enter] or fill in your country's two letter code. make sure you type in the real name of your secure server (a valid DNS name) and not any aliases which the server may have. but you must follow these guidelines: • • Do not abbreviate the locality or state. For Common Name.crt/server. Creating a Self-Signed Certificate You can create your own self-signed certificate. For example. #. and etc. any other documentation that they require. Avoid special characters like @. • • • • The file /etc/httpd/conf/ssl. 26. they send a certificate to you (usually by email). Note that a self-signed certificate does not provide the security guarantees of a CA-signed certificate.5 Types of Certificates for more details about certificates. Save (or cut and paste) the certificate that they send you as /etc/httpd/conf/ssl. Write them out (for example. and your payment to them. follow the instructions they provide on their website. Refer to Section 26. If you are sending this CSR to a CA. be very careful to provide correct information for all of the fields. St. Louis should be written out as Saint Louis). just press [Enter] to accept the blank default for both inputs. CAs rejects CSRs which include information they perceive as invalid. CAs check the information provided in the CSR to determine whether your organization is responsible for what you provided as the Common Name. !. All of these should be self-explanatory.com Email Address []:admin@example. &. but especially for the Organization Name and the Common Name.8. Some CAs reject a certificate request which contains a special character. is GB. Be sure to keep a backup of this file. After you have decided on a CA. Apache HTTP Secure Server Configuration Common Name (your name or server's hostname) []:test.crt. shown like the following: Country Name (2 letter code) [GB]: The default input. If your company name includes an ampersand (&). Their instructions tell you how to send your certificate request. the first information required is the name of the country where the certificate is to be used. This file is your certificate request.example. To continue without entering these fields. ready to send to your CA. After you have fulfilled the CA's requirements. in brackets.csr/server.csr is created when you have finished entering your information. . spell it out as "and" instead of "&. You have to type in the rest of the values.218 Chapter 26.
cnf Enter pass phrase: Next.key/server.crt/server.Chapter 26.com Note Note the s after http. a self-signed certificate is created in certificate with following the command: /sbin/service httpd restart 26.com Email Address []:myemail@example. . There are quite a few fields but you can leave some blank For some fields there will be a default value.crt/server.key -x509 -days 365 -out /etc/httpd/conf/ssl.com with your domain name): https://server. you are asked for more information.example.crt Using configuration from /usr/share/ssl/openssl. Organizational Unit Name (eg. first create a random key using the instructions provided in Section 26.9. make sure you are in the /usr/share/ssl/certs/ directory. ----Country Name (2 letter code) [GB]:US State or Province Name (full name) [Berkshire]:North Carolina Locality Name (eg. Testing The Certificate To test the test certificate installed by default. Once you have a key. If you enter '.6 Generating a Key.example. or a self-signed certificate. The computer's output and a set of inputs looks like the following (provide the correct information for your organization and host): You are about to be asked to enter information that will be incorporated into your certificate request. \ /usr/bin/openssl req -new -key /etc/httpd/conf/ssl.com /etc/httpd/conf/ssl. The https: prefix is used for secure HTTP transactions.example. section) []:Documentation Common Name (your name or server's hostname) []:myhost.crt. Restart the secure server after generating the After you provide the correct information. the field will be left blank. city) [Newbury]:Raleigh Organization Name (eg. Apache HTTP Secure Server Configuration 219 To make your own self-signed certificate. Inc. company) [My Company Ltd]:My Company. point your Web browser to the following home page (replacing server.'. either a CA-signed certificate. and type the following command: make testcert The following output is shown and you are prompted for your passphrase (unless you generated a key without a passphrase): umask 77 . What you are about to enter is what is called a Distinguished Name or a DN.
follow the instructions provided by your browser to accept the certificate. The following URL example attempts to connect to a non-secure server listening on port 12331: http://server. • http://www. For example.10. http://www. do not need to specify the port number in a URL (the port number is assumed). because the certificate is not signed by a CA.com> and include the word subscribe in the subject line.1. 26. The standard port for non-secure Web communications is port 80. including a User Manual at . If you are not using a certificate from a CA.com The standard port for secure Web communications is port 443. Accessing The Server To access your secure server.modssl.modssl. Apache HTTP Secure Server Configuration If you are using a CA-signed certificate from a well-known CA.7 Additional Resources for more information about the Apache HTTP Server.com/mailman/listinfo/redhat-secure-server — The redhat-secure-server mailing list.redhat. However.com:12331 26. Once your browser accepts the certificate. 26. your secure server displays a default home page.example. you must specify the port number in every URL which is intended to connect to the server on the non-standard port. use a URL similar to the following: https://server. anything other than 80 or 443).com Your non-secure server can be accessed using an URL similar to the following: http://server. you may have configured your server so that you have a virtual host running non-secured on port 12331. Useful Websites • http://www.11. Your browser does not automatically recognize a test or a self-signed certificate. Any URLs intended to connect to that virtual host must specify the port number in the URL.example. Additional Resources Refer to Section 25. The website includes a wealth of documentation. your browser probably automatically accepts the certificate (without prompting you for input) and creates the secure connection. The secure server default configuration listens on both of the two standard ports. if you configure your server to listen on a non-standard port (for example. Therefore.org/docs/. You can also subscribe to the redhat-secure-server mailing list by emailing <email@example.com Chapter 26.org/ — The mod_ssl website is the definitive source for information about mod_ssl.example.
2.Chapter 26. 2nd edition. Related Books • Apache: The Definitive Guide. .11. Inc. O'Reilly & Associates. by Ben Laurie and Peter Laurie. Apache HTTP Secure Server Configuration 221 26.
222 Chapter 26. Apache HTTP Secure Server Configuration .
. the username and password combination must be verified. refer to the Red Hat Enterprise Linux Reference Guide. 27. network authentication methods. and SMB as authentication protocols. To disable an option. and other times the system defers the authentication to a user database on a remote system. are not allowed through the firewall. User Information The User Information tab has several options. To enable an option. click the checkbox beside it to clear the checkbox. the changes made take effect immediately. type the command authconfig as root at a shell prompt. LDAP. The Authentication Configuration Tool provides a graphical interface for configuring NIS. in an XTerm or a GNOME terminal). Sometimes the information to verify the user is located on the local system. select the Main Menu Button (on the Panel) => System Settings => Authentication or type the command system-config-authentication at a shell prompt (for example. This chapter does not explain each of the different authentication types in detail. and Hesiod to retrieve user information as well as for configuring LDAP. it explains how to use the Authentication Configuration Tool to configure them. Instead. To start the text-based version. Click OK to exit the program and apply the changes. For more information about the specific authentication types. click the empty checkbox beside it. Kerberos. including NIS and LDAP.Chapter 27. or authenticated. Authentication Configuration When a user logs in to a Red Hat Enterprise Linux system. Important After exiting the authentication program. To start the graphical version of the Authentication Configuration Tool from the desktop.1. Note If you configured a medium or high security level during installation or with the Security Level Configuration Tool. as a valid and active user.
including user information. click the checkbox beside it to clear the checkbox.224 Chapter 27. • Enable LDAP Support — Select this option to configure the system to retrieve user information via LDAP. The nscd package must be installed for this option to work. • • 27. refer to the Red Hat Enterprise Linux Reference Guide. Transport Layer Security is used to encrypt passwords sent to the LDAP server.2. Winbind — Select this option to configure the system to connect to a Windows Active Directory or a Windows domain controller. Click the Configure LDAP button to specify the LDAP Search Base DN and LDAP Server. To disable an option. For more information about LDAP. the portmap and ypbind services are started and are also enabled to start at boot time. If Use TLS to encrypt connections is selected. Authentication The Authentication tab allows for the configuration of network authentication methods. The ypbind package must be installed for this option to work. To enable an option. Click the Configure NIS button to specify the NIS domain and NIS server. • Enable Hesiod Support — Select this option to configure the system to retrieve information from a remote Hesiod database. Cache User Information — Select this option to enable the name service cache daemon ( nscd) and configure it to start at boot time. as well as server authentication options can be configured. If NIS support is enabled. User information can be accessed. click the empty checkbox beside it. The hesiod package must be installed. the daemon attempts to find it via broadcast. . Authentication Configuration Figure 27-1. The openldap-clients package must be installed for this option to work. If the NIS server is not specified. User Information The following list explains what each option configures: • Enable NIS Support — Select this option to configure the system as an NIS client which connects to an NIS server for user and password authentication.
Click the Configure SMB button to specify: • • Workgroup — Specify the SMB workgroup to use. Authentication The following explains what each option configures: • Enable Kerberos Support — Select this option to enable Kerberos authentication. The shadow-utils package must be installed for this option to work. • Winbind — Select this option to configure the system to connect to a Windows Active Directory or a Windows domain controller. LDAP Server — Specify the IP address of the LDAP server. Click the Configure Kerberos button to configure: • • • Realm — Configure the realm for the Kerberos server.Chapter 27. The krb5-libs and krb5-workstation packages must be installed for this option to work. • Enable LDAP Support — Select this option to have standard PAM-enabled applications use LDAP for authentication. • Enable SMB Support — This option configures PAM to use an SMB server to authenticate users. refer to the Users and Groups chapter in the Red Hat Enterprise Linux Reference Guide. Shadow passwords are enabled by default during installation and are highly recommended to increase the security of the system. Click the Configure LDAP button to specify the following: • • • Use TLS to encrypt connections — Use Transport Layer Security to encrypt passwords sent to the LDAP server. Domain Controllers — Specify the SMB domain controllers to use. The openldap-clients package must be installed for this option to work. Refer to the Red Hat Enterprise Linux Reference Guide for more information on Kerberos. Admin Servers — Specify the administration server(s) running kadmind. composed of one or more KDCs and a potentially large number of clients. User information can be accessed. LDAP Search Base DN — Retrieve user information by its Distinguished Name (DN). which is the server that issues Kerberos tickets. Refer to the Red Hat Enterprise Linux Reference Guide for more information about LDAP. Authentication Configuration 225 Figure 27-2. • Use Shadow Passwords — Select this option to store passwords in shadow password format in the /etc/shadow file instead of /etc/passwd. . as well as server authentication options can be configured. KDC — Define the Key Distribution Center (KDC). The realm is the network that uses Kerberos. For more information about shadow passwords.
The command line version can be used in a configuration script or a kickstart script. 27. which allows passwords to be up to 256 characters instead of eight characters or less.3. Command Line Version The Authentication Configuration Tool can also be run as a command line tool with no interface. It is selected by default during installation and is highly recommended for increased security. Authentication Configuration Use MD5 Passwords — Select this option to enable MD5 passwords. The authentication options are summarized in Table 27-1. Option --enableshadow --disableshadow --enablemd5 --disablemd5 --enablenis --disablenis --nisdomain=<domain> --nisserver=<server> --enableldap --disableldap --enableldaptls --disableldaptls --enableldapauth --disableldapauth --ldapserver=<server> --ldapbasedn=<dn> --enablekrb5 --disablekrb5 --krb5kdc=<kdc> --krb5adminserver=<server> --krb5realm=<realm> Description Enable shadow passwords Disable shadow passwords Enable MD5 passwords Disable MD5 passwords Enable NIS Disable NIS Specify NIS domain Specify NIS server Enable LDAP for user information Disable LDAP for user information Enable use of TLS with LDAP Disable use of TLS with LDAP Enable LDAP for authentication Disable LDAP for authentication Specify LDAP server Specify LDAP base DN Enable Kerberos Disable Kerberos Specify Kerberos KDC Specify Kerberos administration server Specify Kerberos realm .226 • Chapter 27. Tip These options can also be found in the authconfig man page or by typing authconfig --help at a shell prompt.
Chapter 27. Authentication Configuration Option --enablekrb5kdcdns --disablekrb5kdcdns --enablekrb5realmdns --disablekrb5realmdns --enablesmbauth --disablesmbauth --smbworkgroup=<workgroup> --smbservers=<server> --enablewinbind --disablewinbind --enablewinbindauth --disablewinbindauth --smbsecurity=<user|server|domain|ads> --smbrealm=<STRING> --smbidmapuid=<lowest-highest> --smbidmapgid=<lowest-highest> --winbindseparator=<\> 227 Description Enable use of DNS to find Kerberos KDCs Disable use of DNS to find Kerberos KDCs Enable use of DNS to find Kerberos realms Disable use of DNS to find Kerberos realms Enable SMB Disable SMB Specify SMB workgroup Specify SMB servers Enable winbind for user information by default Disable winbind for user information by default Enable winbindauth for authentication by default Disable winbindauth for authentication by default Security mode to use for Samba and winbind Default realm for Samba and winbind when security=ads UID range winbind assigns to domain or ADS users GID range winbind assigns to domain or ADS users Character used to separate the domain and user part of winbind usernames if winbindusedefaultdomain is not enabled Directory that winbind users have as their home Group that winbind users have as their primary group Shell that winbind users have as their default login shell Configures winbind to assume that users with no domain in their usernames are domain users --winbindtemplatehomedir=</home/%D/%U> --winbindtemplateprimarygroup=<nobody> --winbindtemplateshell=</bin/false> --enablewinbindusedefaultdomain .
ypbind. or nscd services even if they are configured Do not display the user interface Probe and display network defaults --winbindjoin=<Administrator> --enablewins --disablewins --enablehesiod --disablehesiod --hesiodlhs=<lhs> --hesiodrhs=<rhs> --enablecache --disablecache --nostart --kickstart --probe Table 27-1. Command Line Options .228 Option --disablewinbindusedefaultdomain Chapter 27. Authentication Configuration Description Configures winbind to assume that users with no domain in their usernames are not domain users Joins the winbind domain or ADS realm now as this administrator Enable WINS for hostname resolution Disable WINS for hostname resolution Enable Hesiod Disable Hesiod Specify Hesiod LHS Specify Hesiod RHS Enable nscd Disable nscd Do not start or stop the portmap.
241 32................................................................................................................ User and Group Configuration ....................................................................... Console Access................................................................. 275 36...................... 235 30.......................................... System Configuration Part of a system administrator's job is configuring the system for various tasks................................................................................................................................................................................ and hardware configurations............................... 293 39................................. Automated Tasks ......................V................................................................... types of users................................. 247 34...................... Table of Contents 28.... Printer Configuration .................................................. 285 38...................................................................... Mail Transport Agent (MTA) Configuration ........ 257 35....................... Log Files............................................................................................................... 243 33.... Mouse Configuration .................................................................................. Manually Upgrading the Kernel. Keyboard Configuration ....... 281 37.......... 231 29.................... 297 ......... 239 31................. X Window System Configuration ............ Kernel Modules ................... Date and Time Configuration .......................................................................................................................................... This section explains how to configure a Red Hat Enterprise Linux system...............
If one of them is. . every user who logs in at the console is allowed to run programs that accomplish tasks normally restricted to the root user. and reboot. like the following: stephen jack sophie According to this example shutdown. by taking the following steps: 1. Console Access When normal (non-root) users log into a computer locally. Disabling Shutdown Via [Ctrl]-[Alt]-[Del] By default. one of the users has to essentially win the race to access the files. The shutdown. and so on) that they would not otherwise be able to access Since there are multiple consoles on a single computer and multiple users can be logged into the computer locally at the same time. For more information on shutdown. Once the first user logs out. one per line. CD-ROMs.1. The first user to log in at the console owns those files. they are given two types of special permissions: 1. They can access certain files (normally special device files used to access diskettes.allow. 28.allow file is a list of usernames. jack. In contrast.Chapter 28. the shutdown of the system continues.allow in /etc. the users stephen. the console-accessible programs include halt. refer to the shutdown man page. To completely disable this ability. and sophie are allowed to shutdown the system from the console using [Ctrl]-[Alt]-[Del]. these actions can be included as menu items in a graphical user interface. 2. If X is running. /etc/inittab specifies that your system is set to shutdown and reboot in response to a [Ctrl]-[Alt]-[Del] key combination used at the console.allow file. you may want to allow certain non-root users the right to shutdown or reboot the system from the console using [Ctrl]-[Alt]-[Del].allow file. so that it reads: ca::ctrlaltdel:/sbin/shutdown -a -t3 -r now The -a flag tells shutdown to look for the /etc/shutdown. the shutdown -a command in /etc/inittab checks to see if any of the users in /etc/shutdown. Create a file named shutdown. You can restrict this privilege to certain users. if not. an error message is written to the system console instead. As shipped. comment out the following line in /etc/inittab by putting a hash mark (#) in front of it: ca::ctrlaltdel:/sbin/shutdown -t3 -r now Alternatively. the next user who logs in owns the files. When that key combination is used.allow file should list the usernames of any users who are allowed to shutdown the system using [Ctrl]-[Alt]-[Del].allow (or root) are logged in on a virtual console. poweroff. The format of the shutdown. Add the -a option to the /etc/inittab line shown above. They can run certain programs that they would not otherwise be able to run 2.
apps/* In environments where the console is otherwise secured (BIOS and boot loader passwords are set. say. and so forth). and reboot. you may not want to allow any user at the console to run poweroff.0. Disabling Console Program Access To disable access by users to console programs.apps/poweroff rm -f /etc/security/console.3.apps/reboot 28.example. you could add the following line: <scanner>=/dev/scanner /dev/usb/scanner* (Of course.perms file to determine the permissions for users at the system console. run the following command as root: rm -f /etc/security/console.so module uses the /etc/security/console. However. [Ctrl]-[Alt]-[Delete] is disabled. Look in the last section of /etc/security/console. To remove these abilities.4. the default file has a line that looks like this: <console>=tty[0-9][0-9]* vc/[0-9][0-9]* :[0-9]\. Console Access 28. you can edit the file so that these instructions no longer apply.2. which are accessible from the console by default. For example. you can change that line to read: <console>=tty[0-9][0-9]* vc/[0-9][0-9]* :[0-9]\.perms.apps/halt rm -f /etc/security/console. The default is to define that local virtual consoles and local X servers are considered local. either an X server with a name like :0 or mymachine. Defining the Console The pam_console. your hard drive. make sure that /dev/scanner is really your scanner and not. Make sure that any lines you add refer to the appropriate device.[0-9] :[0-9] When users log in. The second step is to define what is done with those files. halt. there is a section with lines like: <floppy>=/dev/fd[0-1]* \ /dev/floppy/* /mnt/floppy* <sound>=/dev/dsp* /dev/audio* /dev/midi* \ /dev/mixer* /dev/sequencer \ /dev/sound/* /dev/beep \ /dev/snd/* <cdrom>=/dev/cdrom* /dev/cdroms/* /dev/cdwriter* /mnt/cdrom* You can add your own lines to this section.[0-9] :[0-9] /dev/ttyS1 28. Making Files Accessible From the Console In /etc/security/console. but if you want to consider the serial terminal next to you on port /dev/ttyS1 to also be local. or a device like /dev/ttyS0 or /dev/pts/2. The syntax of the file is very flexible.perms for lines similar to: .) That is the first step. the power and reset switches are disabled. run the following commands as root: rm -f /etc/security/console.com:1.232 Chapter 28. they are attached to some sort of named terminal. if necessary.
Create a PAM configuration file for the foo service in /etc/pam.so session optional /lib/security/pam_timestamp. so the application that you wish to run must be there.d/. After the authentication expires (the default is five minutes). consolehelper is called.Chapter 28. This module is included in the pam package. the PAM configuration file in etc/pam. 28.so The first line that begins with auth should be after any other auth sufficient lines.d/halt /etc/pam. First of all. such as our sample foo program. When an application is started and proper authentication is provided (the root password). To authenticate the user.d/foo is a copy of /etc/pam.5. and the line that begins with session should be after any other session optional lines. During this time. Create the file /etc/security/console. Enabling Console Access for Other Applications To make other applications accessible to console users. Console Access <console> 0660 <floppy> 0660 root. To enable this feature. any other application that is configured to use pam_timestamp and run from the same session is automatically authenticated for the user — the user does not have to enter the root password again. and then modify the file if you want to change the behavior: cp /etc/pam.floppy <console> 0600 <sound> 0640 root <console> 0600 <cdrom> 0600 root. consolehelper asks for the user's password if /etc/pam. . which authenticates the user with the help of /usr/sbin/userhelper.apps/foo 3. An easy way to do this is to start with a copy of the halt service's PAM configuration file.d/halt (otherwise. a bit more work is required. a timestamp file is created. do the following steps: 1. an application can be configured to use the pam_timestamp module to remember (or cache) a successful authentication attempt. the device is owned by root and still has the permissions 0600 (now readable and writable by root only). you are given ownership of the /dev/scanner device with the permissions of 0600 (readable and writable by you only).d/foo) and then runs /usr/sbin/foo with root permissions. When you log out. when /usr/bin/foo is executed. it does precisely what is specified in /etc/pam. In the PAM configuration file. the icon disappears. By default. Create a link from the name of your application. to the /usr/bin/consolehelper application: cd /usr/bin ln -s consolehelper foo 2.disk 233 and add a line like: <console> 0600 <scanner> 0600 root Then.d/foo Now. the running the GNOME or KDE desktop environment.apps/foo: touch /etc/security/console. a successful authentication is cached for five minutes. If an application configured to use pam_timestamp is successfully authenticated from the Main icon is displayed in the notification area of the panel if you are Menu Button (on the Panel).d/ must include the following lines: auth sufficient /lib/security/pam_timestamp. when you log in at the console. After verifying that. console access only works for applications which reside in /sbin/ or /usr/sbin/.
For example. 28. console access is not appropriate for you and your non-root users are required access to your system's diskette drive. the gpasswd command can be used to add user fred to the floppy group: gpasswd -a fred floppy Now.6. for whatever reason. Console Access The user can select to forget the cached authentication by clicking on the icon and selecting the option to forget authentication. The floppy Group If. . this can be done using the floppy group. Add the user(s) to the floppy group using the tool of your choice. user fred is able to access the system's diskette drive from the console.234 Chapter 28.
go to Applications (the main menu on the panel) => System Settings => Date & Time From the desktop. Time and Date Properties .1. You must be running the X Window System and have root privileges to use the tool. Time and Date Properties As shown in Figure 29-1. Date and Time Configuration The Time and Date Properties Tool allows the user to change the system date and time.Chapter 29. the first tabbed window that appears is for configuring the system date and time. to configure the time zone used by the system. Type the command system-config-date. in an XTerm or a GNOME terminal). system-config-time. There are three ways to start the application: • • • From the desktop. 29. or dateconfig at a shell prompt (for example. and to setup the Network Time Protocol (NTP) daemon to synchronize the system clock with a time server. right-click on the time in the toolbar and select Adjust Date and Time. Figure 29-1.
To change the time. This enables the Server pulldown menu. and the time zone settings. You can choose one of the predefined servers or type a server name in the pulldown menu. Network Time Protocol (NTP) Properties As shown in Figure 29-2. Clicking the OK button applies any changes made to the date and time. the second tabbed window that appears is for configuring NTP.236 Chapter 29. It also exits the program. Clicking the OK button applies any changes made to the date and time. and the time zone settings. 29. After clicking OK. Minute. and Second in the Time section. and click on the day of the week to change the day of the week. Date and Time Configuration To change the date. The application allows you to configure an NTP daemon to synchronize your system clock with a remote server. use the arrows to the left and right of the year to change the year. use the arrows to the left and right of the month to change the month. the NTP daemon settings. . To enable this feature. Changes take place until after the OK button is clicked. select Enable Network Time Protocol. Changes take place after the OK button is clicked. Figure 29-2. use the up and down arrow buttons beside the Hour.2. the configuration is saved and the NTP daemon is started (or restarted if it is already running). Your system does not start synchronizing with the NTP server until you click OK. the NTP daemon settings. NTP Properties The Network Time Protocol (NTP) daemon synchronizes the system clock with a remote time server or time source (such as a satellite). It also exits the program.
UTC stands for the Universal Time.Chapter 29. click the Time Zone tab. . select the System clock uses UTC option. also known as Greenwich mean time (GMT). Coordinated. click on the city that represents the desired time zone. The time zone can be changed by either using the interactive map or by choosing the desired time zone from the list below the map. Figure 29-3. the third tabbed window that appears is for configuring the system time zone. Click OK to apply the changes and exit the program. Other time zones are determined by adding or subtracting from the UTC time. Timezone Properties If your system clock is set to use UTC. To use the map. To configure the system time zone. Date and Time Configuration 237 29. A red X appears and the time zone selection changes in the list below the map. Time Zone Configuration As shown in Figure 29-3.3.
238 Chapter 29. Date and Time Configuration .
English) and click OK.Chapter 30. you should log out of your graphical desktop session and log back in. or type the command system-config-keyboard at a shell prompt. Figure 30-1. To start the Keyboard Configuration Tool. U. . Keyboard Configuration Tool Select a keyboard layout from the list (for example. For changes to take effect. To configure a different keyboard layout after installation. select Applications (the main menu on the panel) => System Settings => Keyboard.S. use the Keyboard Configuration Tool. Keyboard Configuration The installation program allows users to configure a keyboard layout for their systems.
240 Chapter 30. Keyboard Configuration .
If the X Window System is not running. . Tip Select the Generic . All the mouse types are appended with PS/2. To start the Mouse Configuration Tool. in an XTerm or GNOME terminal). If there is not an exact match. This specifies the mouse port. select one of the Generic entries. Figure 31-1. to enable the scroll button on the mouse.Wheel Mouse entry. type the command system-config-mouse at a shell prompt (for example. . A PS/2 mouse port looks similar to A serial mouse port looks similar to A USB mouse port looks similar to . To configure a different mouse type for the system. the text-based version of the tool is started. serial. with the proper mouse port. . Mouse Configuration The installation program allows users to select the type of mouse connected to the system. Select Mouse Select the new mouse type for the system. use the Mouse Configuration Tool. The built-in pointing device such as a touch pad on a laptop computer is usually PS/2 compatible. select the generic match that is most compatible with the system and the mouse.Chapter 31. or USB in parentheses. If the specific mouse model is not listed. based on the mouse's number of buttons and its interface.
When this option enabled. select Emulate 3 buttons to use a two-button mouse as a three-button mouse. Click OK to save the new mouse type. If the mouse only has two buttons. If a serial port mouse is selected. and other middle mouse button functions. The changes are also written to the X Window System configuration file /etc/X11/xorg. the mouse type change is not automatically applied to the current X session. such as /dev/ttyS0 for the mouse.conf. . log out of the graphical desktop and log back in. pasting text. Tip To reset the order of the mouse buttons for a left-handed user. clicking the two mouse buttons simultaneously emulates a middle mouse button click. click the Serial devices button to configure the correct serial device number.242 Chapter 31. however. and the console mouse service. gpm is restarted. and select Left-handed mouse for the mouse orientation. To enable the new mouse type. The selection is written to the file /etc/sysconfig/mouse. go to Applications (the main menu on the panel) => Preferences => Mouse. Mouse Configuration The scroll button on a wheel mouse can be used as the middle mouse button for cutting text.
the higher the resolution.Chapter 32.1. The display of a monitor consists of tiny dots called pixels. video card. use the X Configuration Tool. log out of the graphical desktop and log back in to enable the changes. Display Settings The Display tab allows users to change the resolution and color depth. Display Settings . in an XTerm or GNOME terminal). the resolution 1024x768 means that 1024 horizontal pixels are used and 768 vertical pixels are used. the smaller the desktop icons appear. After changing any of the settings. select Applications (the main menu on the panel) => System Settings => Display. the more images the monitor can display at one time. a small version of X is started to run the program. the system's monitor. and display settings are configured. The higher the resolution numbers. the more contrast between colors. To change any of these settings for the system. The higher the color depth. The number of pixels displayed at one time is called the resolution. The color depth of the display determines how many possible colors are displayed. 32. or type the command system-config-display at a shell prompt (for example. If the X Window System is not running. To start the X Configuration Tool. For example. For example. X Window System Configuration During installation. and the more icons it takes to fill the entire desktop. Figure 32-1.
244 Chapter 32. click the Configure button beside its settings. Dual Head Display Settings If multiple video cards are installed on the system. To change the video card type or any of its settings. 32. it probes the monitor and video card. X Window System Configuration 32. as shown in Figure 32-3. Display Hardware Settings When the application is started. click the corresponding Configure button.2. dual head monitor support is available and is configured via the Dual head tab. . Figure 32-2. the information for it is shown on the Hardware tab as shown in Figure 32-2. Display Hardware Settings To change the monitor type or any of its settings. If the hardware is probed properly.3.
selecting Spanning Desktops allows both monitors to use an enlarged usable workspace. X Window System Configuration 245 Figure 32-3. To configure the second monitor type or any of its settings. .Chapter 32. check the Use dual head checkbox. Dual Head Display Settings To enable use of dual head. similar to laptops. For the Desktop layout option. click the corresponding Configure button. Selecting Individual Desktops creates a mirrored workspace effect.
X Window System Configuration .246 Chapter 32.
type the first few letters of the name in the Search filter field. including the system users. click on the column name. type the command system-config-users at a shell prompt (for example. Adding a New User To add a new user. click the Users tab. Type the username and full name for the new user in the appropriate fields. you must be running the X Window System. To find a specific user or group. go to Applications (the main menu on the panel) => System Settings => Users & Groups. Press [Enter] or click the Apply filter button.Chapter 33. To sort the users or groups. click the Add User button. To view a list of local groups on the system. Figure 33-1. and special characters. To view all users. . It is also recommended that the password not be based on a dictionary term as well as the password be a combination of letters. and delete local users and groups. have root privileges. Tip The longer the user's password. 33. add. click the Groups tab. in an XTerm or a GNOME terminal). User Manager does not display system users. User Manager To view a list of local users on the system. A window as shown in Figure 33-2 appears. Or. numbers. User and Group Configuration The User Manager allows you to view. To start the User Manager from the desktop. modify. Red Hat Enterprise Linux reserves user IDs below 500 for system users. By default. and have the system-config-users RPM package installed. uncheck Preferences => Filter system users and groups from the pulldown menu. the more difficult it is for an intruder to guess it and use it to access the user's account without permission. To use the User Manager. The password must be at least six characters.1. The users or groups are sorted by the value of that column. The filtered list is displayed. Type the user's password in the Password and Confirm Password fields.
click on the User tab. select the user. A window similar to Figure 33-3 appears. Whenever you create a new user. The default home directory is /home/username/. such as password expiration. Red Hat Enterprise Linux reserves user IDs below 500 for system users. Red Hat Enterprise Linux uses a user private group (UPG) scheme. select the primary group for the user.248 Chapter 33. select Specify user ID manually. To specify a user ID for the user. the next available user ID starting with number 500 is assigned to the new user.2 Modifying User Properties for more information. click on the Users tab. You can change the home directory that is created for the user. it offers a new convention. If you are not sure which shell to select. select the Groups tab. If the option is not selected. Select the groups that you want the user to be a member of. Click OK to create the user. by default. default configuration files are copied from the /etc/skel/ directory into the new home directory. The UPG scheme does not add or change anything in the standard UNIX way of handling groups. and click OK. To add the user to more user groups. and click Properties. modify the user's properties after adding the user. a unique group with the same name as the user is created. Refer to Section 33. If you select to create the home directory. unselect Create a private group for the user. and click Properties from the menu (or choose File => Properties from the pulldown menu). 33. In the User Properties window. If you do not want to create this group. . Modifying User Properties To view the properties of an existing user. New User To configure more advanced user properties.2. select the user from the user list. Figure 33-2. User and Group Configuration Select a login shell. accept the default value of /bin/bash. or you can choose not to create the home directory by unselecting Create home directory.
User and Group Configuration 249 Figure 33-3. Select User account is locked to lock the user account so that the user cannot log in to the system. A window similar to Figure 33-4 appears. Click OK to create the group. New Group To add users to the group. select Specify group ID manually and select the GID. select Enable password expiration. The number of days before the user's password expires. Adding a New Group To add a new user group. and days before the account becomes inactive can also be changed. Type the name of the new group to create. Figure 33-4. password.Chapter 33. Enter the date in the provided fields.4 Modifying Group Properties. To force the user to change passwords after a certain number of days. Groups — Select the groups that you want the user to be a member of and the user's primary group. Account Info — Select Enable account expiration if you want the account to expire on a certain date. . User Properties The User Properties window is divided into multiple tabbed pages: • • User Data — Shows the basic user information configured when you added the user. or login shell. Password Info — This tab shows the date that the user's password last changed. To specify a group ID for the new group.3. Red Hat Enterprise Linux reserves group IDs lower than 500 for system groups. the number of days before the user is warned to change passwords. refer to Section 33. The new group appears in the group list. • • 33. home directory. click the Add Group button. Use this tab to change the user's full name.
Figure 33-5. Click OK to modify the users in the group. A window similar to Figure 33-5 appears. 33. 33. Adding a User To add a user to the system: 1. User and Group Configuration 33. use this section to configure users and groups.5. Option -c comment -d home-dir -e date Description Comment for the user Home directory to be used instead of default /home/username/ Date for the account to be disabled in the format YYYY-MM-DD . Command Line Configuration If you prefer command line tools or do not have the X Window System installed. Unlock the account by issuing the passwd command to assign a password and set password aging guidelines: passwd <username> Command line options for useradd are detailed in Table 33-1. Modifying Group Properties To view the properties of an existing group. select the group from the group list and click Properties from the menu (or choose File => Properties from the pulldown menu).1. Issue the useradd command to create a locked user account: useradd <username> 2. Select additional users to be added to the group.5.250 Chapter 33. Group Properties The Group Users tab displays which users are members of the group. or unselect users to be removed from the group.4.
which must be unique and greater than 499 -g group-name -G group-list -m -M -n -r -p password -s -u uid Table 33-1.5.2. use the chage command.) Create the home directory if it does not exist Do not create the home directory Do not create a user private group for the user Create a system account with a UID less than 500 and without a home directory The password encrypted with crypt User's login shell. the account is not be disabled after the password expires.3. groupadd Command Line Options 33. Option -g gid -r -f Description Group ID for the group. Password Aging For security reasons. but the group already exists. If -1 is specified. which must be unique and greater than 499 Create a system group with a GID less than 500 Exit with an error if the group already exists (The group is not altered.) If -g and -f are specified. use the command groupadd: groupadd <group-name> Command line options for groupadd are detailed in Table 33-2. the account is disabled immediately after the password expires.5. of which the user is a member.Chapter 33. (If 0 is specified. separated by commas.) List of additional (other than default) group names or group numbers. Adding a Group To add a group to the system. useradd Command Line Options 33. To configure password expiration for a user from a shell prompt.) Group name or group number for the user's default group (The group must exist prior to being specified here. . followed by an option from Table 33-3. the -g option is ignored Table 33-2. User and Group Configuration Option -f days 251 Description Number of days after the password expires until the account is disabled. This can be done when adding or editing a user on the Password Info tab of the User Manager. it is good practice to require users to change their passwords periodically. which defaults to /bin/bash User ID for the user. followed by the username of the user. (The groups must exist prior to being specified here.
Option -m days -M days Description Specify the minimum number of days between which the user must change passwords. 1970 the password was changed. Specify the number of days before the password expiration date to warn the user. To force a user to configure a password the first time the user logs in at the console. If the value is 0. the user must change passwords before using the account. is in place. if any. Note. Lock the user's password — If the user does not exist. Specify the maximum number of days for which the password is valid. User and Group Configuration Important Shadow passwords must be enabled to use the chage command. the password does not expire. this process does not work if the user logs in using the SSH protocol. it displays the current password aging values and allows them to be changed. chage Command Line Options Tip If the chage command is followed directly by a username (with no options). follow these steps. the number of days since January 1. . the account is not locked after the password expires. If a system administrator wants a user to set a password the first time the user log in. use the useradd command to create the user account. If the value is 0. in the format YYYY-MM-DD. Specify the date on which the account is locked. Specify the number of days since January 1. 1970 can also be used.252 Chapter 33. 1. This value forces immediate password expiration no matter what password aging policy. the user's initial or null password can be set to expire immediately. -d days -I days -E date -W days Table 33-3. lock it with the command: usermod -L username 2. but do not give it a password so that it remains locked. 1970). If the password is already enabled. Instead of the date. When the number of days specified by this option plus the number of days specified with the -d option is less than the current day. forcing the user to change it immediately after logging in for the first time. Specify the number of inactive days after the password expiration before locking the account. Force immediate password expiration — Type the following command: chage -d 0 username This command sets the value for the date the password was last changed to the epoch (January 1.
UIDs and GIDs below 500 are reserved for system use. "credits" or "license" for more information. The home directory for juan is set to /home/juan/. It displays the following: Python 2. it is recommended that the administrator verifies that the user is ready to log in when the account is unlocked. >>> • At the prompt. 09:57:09) [GCC 3."salt") The output is the encrypted password. A new line for juan is created in /etc/passwd.2 (#1. a null password can be assigned using the following command: usermod -p "" username Caution While using a null password is convenient for both the user and the administrator. To assign an initial password. In either case. there is a slight risk that a third party can log in first and access the system. (Under Red Hat Enterprise Linux.2. The line has the following characteristics: • • • • • • It begins with the username juan. the dot (. or the slash (/) character such as ab or 12): import crypt. the user is prompted for a new password.) A GID at or above 500 is created. digits.6. upon initial log in. type the following (replacing password with the password to encrypt and salt with a combination of exactly 2 upper or lower case alphabetic characters. User and Group Configuration 253 3. Explaining the Process The following steps illustrate what happens if the command useradd juan is issued on a system that has shadow passwords enabled: 1. similar to 12CsGd8FRcMSM. without a leading or trailing blank space. "copyright".Chapter 33. use the following steps: • Start the command line Python interpreter with the python command. print crypt. .1 20021207 (Red Hat Enterprise Linux 4 3. To minimize this threat. 33. into the following command: usermod -p "encrypted-password" username Instead of assigning an initial password. The optional GECOS information is left blank. There is an x for the password field indicating that the system is using shadow passwords. Unlock the account — There are two common approaches to this step. A UID at or above 500 is created. The administrator can assign an initial password or assign a null password.2. Warning Do not use the passwd command to set the password as it disables the immediate password expiration just configured.) character. Cut and paste the exact encrypted password output.2. • • Type [Ctrl]-[D] to exit the Python interpreter.crypt("password". Dec 10 2002.1-2)] on linux2 Type "help".
3. a locked account called juan exists on the system. Additional Information Refer to these resources for more information on user and group management. For more information on user private groups.254 • Chapter 33. write. User and Group Configuration The default shell is set to /bin/bash. All other permissions are denied. and execute privileges only for the user juan. However. which locks the group. 2. it is placed in the /etc/shadow file on the new line for the user. 6. The files within the /etc/skel/ directory (which contain default user settings) are copied into the new /home/juan/ directory. The GID matches the one listed for user juan in /etc/passwd. . A directory for user juan is created in the /home/ directory. Note If an encrypted password is passed using the -p flag. • The password is set to never expire. At this point.1 Adding a New User. A new line for a group named juan is created in /etc/group. A new line for juan is created in /etc/shadow. The line created in /etc/group has the following characteristics: • • • It begins with the group name juan. A new line for a group named juan is created in /etc/gshadow. An x appears in the password field indicating that the system is using shadow group passwords. 4.7. This directory is owned by user juan and group juan. An exclamation point (!) appears in the password field of the /etc/gshadow file. Two exclamation points (!!) appear in the password field of the /etc/shadow file. it has read. set password aging guidelines. which locks the account. A group with the same name as a user is called a user private group. All other fields are blank. The line has the following characteristics: • • • It begins with the group name juan. 5. the administrator must next assign a password to the account using the passwd command and. refer to Section 33. 33. To activate it. optionally. The line has the following characteristics: • • It begins with the username juan.
Red Hat Enterprise Linux Introduction to System Administration — This companion manual contains more information on managing users and groups as well as managing user resources. .7.Chapter 33. Installed Documentation • The man pages for useradd.2. and chage. groupadd.7. 33. Related Books • • Red Hat Enterprise Linux Reference Guide — This manual gives a list of standard users and groups. User and Group Configuration 255 33. passwd.1. and provides an overview of shadow passwords. discusses user private groups.
256 Chapter 33. User and Group Configuration .
print spool directories. The files are dynamically created when changes are applied with the Printer Configuration Tool as well. the upgrade process preserved the configured queues. Printer Configuration Tool The following types of print queues can be configured: • • Locally-connected — a printer attached directly to the computer through a parallel or USB port. new configuration files are dynamically created. Red Hat Enterprise Linux 4 uses the CUPS printing system. a printer attached to another Red Hat Enterprise Linux system running CUPS on the network). . or type the command system-config-printer. execute the command Important Do not edit the /etc/printcap file or the files in the /etc/cups/ directory. This tool helps maintain the printer configuration file. If a system was upgraded from a previous Red Hat Enterprise Linux version that used CUPS. To force the Printer Configuration Tool to run as a text-based application. select Applications (the main menu on the panel) => System Settings => Printing. system-config-printer-tui from a shell prompt. and print filters. To start the application. Printer Configuration The Printer Configuration Tool allows users to configure a printer. Figure 34-1. also known as IPP (for example. This command automatically determines whether to run the graphical or text-based version depending on whether the command is executed in the graphical desktop environment or from a text-based console. Each time the printer daemon (cups) is started or restarted. Networked CUPS (IPP) — a printer that can be accessed over a TCP/IP network via the Internet Printing Protocol. Using the Printer Configuration Tool requires root privileges.Chapter 34.
Alternatively. Clicking the Apply button saves any changes that you have made and restarts the printer daemon. Networked JetDirect — a printer connected directly to the network through HP JetDirect instead of to a computer. Networked Windows (SMB) — a printer attached to a different system which is sharing a printer over an SMB network (for example.258 • Chapter 34. Adding a Local Printer To add a local printer. and underscores (_). Optionally. The printer name may contain letters. dashes (-). The printer name cannot contain spaces and must begin with a letter. enter a unique name for the printer in the Name text field. • • • Important If you add a new print queue or modify an existing one. click the New button in the main Printer Configuration Tool window to display the window in Figure 34-2. a printer attached to another Red Hat Enterprise Linux system running LPD on the network). you can choose Action => Apply. Printer Configuration Networked UNIX (LPD) — a printer attached to a different UNIX system that can be accessed over a TCP/IP network (for example. enter a short description for the printer. a printer attached to a Microsoft Windows™ machine). such as one attached through a parallel port or USB port on your computer. Networked Novell (NCP) — a printer attached to a different system which uses Novell's NetWare network technology. 34. Adding a Printer In the window shown in Figure 34-3. The changes are not written to the configuration file until the printer daemon is restarted. Figure 34-2. which can contain spaces. Click Forward to proceed. you must apply the changes for them to take effect.1. numbers. .
Refer to Section 34.2. Figure 34-4 appears. . Select Locally-connected from the Select a queue type menu. If you have a firewall configured on the client (the computer sending the print request). and select the device. 34.) Any networked IPP printer found via CUPS browsing appears in the main window under the Browsed queues category. 631. the Printer Configuration Tool browses the network for any shared IPP printers. Adding a Local Printer Next. (This option can be changed by selecting Action => Sharing from the pulldown menu. Click Forward to continue. Printer Configuration 259 Figure 34-3. select the printer type. click Rescan devices to rescan the computer or click Custom device to specify it manually. Selecting a Queue Name After clicking Forward. The device is usually /dev/lp0 for a parallel printer or /dev/usb/lp0 for a USB printer. If no devices appear in the list. Adding an IPP Printer An IPP printer is a printer attached to a different Linux system on the same network running CUPS or a printer configured on another operating system to use IPP.Chapter 34. it must be able to send and receive connections on the incoming UDP port. it must be allowed to send and accept connections on port 631.7 Selecting the Printer Model and Finishing for details. If you have a firewall configured on the print server. Figure 34-4. By default.
In the window shown in Figure 34-3. Click Forward to proceed. enter a short description for the printer. click the New button in the main Printer Configuration Tool window. enter a short description for the printer.7 Selecting the Printer Model and Finishing for details. Printer Configuration If you disable the automatic browsing feature. . Important The networked IPP print server must allow connections from the local system. Refer to Section 34. 34. Select Networked CUPS (IPP) from the Select a queue type menu.3. Optionally. In the window shown in Figure 34-3. Figure 34-5. which can contain spaces. enter a unique name for the printer in the Name text field. The printer name cannot contain spaces and must begin with a letter. which can contain spaces. The printer name cannot contain spaces and must begin with a letter. The printer name may contain letters. you can still add a networked IPP printer by clicking the New button in the main Printer Configuration Tool window to display the window in Figure 34-2. Adding an IPP Printer Text fields for the following options appear: • • Server — The hostname or IP address of the remote machine to which the printer is attached. The printer name may contain letters. Figure 34-5 appears. Refer to Section 34. Optionally.260 Chapter 34. numbers. dashes (-). Click Forward to proceed. Adding a Remote UNIX (LPD) Printer To add a remote UNIX printer. The window shown in Figure 34-2 appears.13 Sharing a Printer for more information. After clicking Forward. select the printer type. enter a unique name for the printer in the Name text field. such as one attached to a different Linux system on the same network. Path — The path to the print queue on the remote machine. numbers. Click Forward to continue. dashes (-). Next. and underscores (_). and underscores (_).
and click Forward.7 Selecting the Printer Model and Finishing for details. The window shown in Figure 34-2 appears. The default printer queue is usually lp. Select Networked Windows (SMB) from the Select a queue type menu. select the printer type. choose this queue type. The printer name may contain letters. dashes (-). Queue — The remote printer queue. Adding a Samba (SMB) Printer To add a printer which is accessed using the SMB protocol (such as a printer attached to a Microsoft Windows system). The printer name cannot contain spaces and must begin with a letter. Adding a Remote LPD Printer Text fields for the following options appear: • • Server — The hostname or IP address of the remote machine to which the printer is attached.4. enter a unique name for the printer in the Name text field. Printer Configuration Select Networked UNIX (LPD) from the Select a queue type menu and click Forward. If the printer is attached to a Microsoft Windows system.Chapter 34. . Optionally. 34. enter a short description for the printer. numbers. In the window shown in Figure 34-3. Click Forward to continue. Important The remote print server must accept print jobs from the local system. 261 Figure 34-6. Next. Refer to Section 34. and underscores (_). which can contain spaces. Click Forward to proceed. click the New button in the main Printer Configuration Tool window.
This dialog window is the same as the one shown when the Specify button is clicked. a dialog window appears prompting you to provide a valid username and password for the shared printer. Text fields for the following options appear: • • • • Workgroup — The name of the Samba workgroup for the shared printer. Click the arrow beside each share name to expand the list. To avoid this. it is possible for others to learn the username and password if they have root access. and the user must have permission to access the printer. The Printer Configuration Tool then attempts to connect to the shared printer. If there are file shares from the server. SMB shares are automatically detected and listed. This user must exist on the Windows system. they are stored unencrypted in files only readable by root and lpd. select the printer type. Warning If you require a username and password. If the printer you are looking for does not appear in the list. Thus. If the shared printer requires a username and password. From the expanded list. Password — The password (if required) for the user specified in the User name field. click the Specify button on the right. you can change it here as well. Printer Configuration Figure 34-7. The default user name is typically guest for Windows servers.262 Chapter 34. User name — The name of the user you must log in as to access the printer. Share — The name of the shared printer on which you want to print. Server — The name of the server sharing the printer. select a printer. then the only possible security compromise would be unauthorized use of the printer. • Click Forward to continue. This name must be the same name defined as the Samba printer on the remote Windows machine. If a workgroup name is required to connect to the share.7 Selecting the Printer Model and Finishing for details. the username and password to access the printer should be different from the username and password used for the user's account on the local Red Hat Enterprise Linux system. Next. If an incorrect share name is specified. Refer to Section 34. . it is recommended that they also use a different password than the one for the print queue. If they are different. Adding a SMB Printer As shown in Figure 34-7. it can be specified in this dialog box. or nobody for Samba servers.
click the New button in the main Printer Configuration Tool window. then the only possible security compromise would be unauthorized use of the printer. enter a unique name for the printer in the Name text field. Printer Configuration 263 34. Queue — The remote queue for the printer on the NCP system. If they are different. they are stored unencrypted in files only readable by root and lpd. the username and password to access the printer should be different from the username and password used for the user's account on the local Red Hat Enterprise Linux system.7 Selecting the Printer Model and Finishing for details. enter a short description for the printer. it is possible for others to learn the username and password if they have root access. and underscores (_). Figure 34-8. Adding a Novell NetWare (NCP) Printer To add a Novell NetWare (NCP) printer. Optionally. Warning If you require a username and password. Adding a JetDirect Printer To add a JetDirect printer. which can contain spaces. . Click Forward to proceed. The printer name may contain letters.6. User — The name of the user you must log in as to access the printer. The window shown in Figure 34-1 appears. select the printer type. Refer to Section 34. To avoid this. Click Forward to proceed.Chapter 34. In the window shown in Figure 34-3. If there are file shares from the server. Next. Password — The password for the user specified in the User field above. numbers.5. The printer name cannot contain spaces and must begin with a letter. Select Networked Novell (NCP) from the Select a queue type menu. Adding an NCP Printer Text fields for the following options appear: • • • • Server — The hostname or IP address of the NCP system to which the printer is attached. Thus. it is recommended that they also use a different password than the one for the print queue. dashes (-). 34. The window shown in Figure 34-1 appears. click the New button in the main Printer Configuration Tool window.
Printer Configuration In the window shown in Figure 34-3. The printers are divided by manufacturers. Figure 34-9. If it was not auto-detected.264 Chapter 34. Select the printer model from the list. Select Networked JetDirect from the Select a queue type menu. and click Forward. select the model from the list. . Port — The port on the JetDirect printer that is listening for print jobs. the next step is to select the printer model. enter a short description for the printer. Select the name of the printer manufacturer from the pulldown menu. Refer to Section 34. and underscores (_). Adding a JetDirect Printer Text fields for the following options appear: • • Printer — The hostname or IP address of the JetDirect printer. which can contain spaces. select the printer type. The printer name may contain letters. The printer name cannot contain spaces and must begin with a letter.7 Selecting the Printer Model and Finishing for details. The printer models are updated each time a different manufacturer is selected. Selecting the Printer Model and Finishing After selecting the queue type of the printer. enter a unique name for the printer in the Name text field. dashes (-). numbers. The default port is 9100. Optionally.7. Next. 34. A window similar to Figure 34-10 appears.
start the Printer Configuration Tool. After applying the changes. select the printer from the list. the remote print server might not have a print driver configured. the remote print server usually has its own print driver.Chapter 34. Click the Apply button in the main window to save your changes and restart the printer daemon. Tip You can select a different print driver after adding a printer. first try selecting Generic as the manufacturer and Raw Print Queue or Postscript Printer as the printer model.7. click the Driver tab.1.8 Printing a Test Page for details. If the test fails.9 Modifying Existing Printers for details. If you select an additional print driver on your local computer. you must review your driver options and select Prerender Postscript. Since a local printer is attached directly to your computer. applying the changes. Try selecting a print driver according to the manufacturer and model of the remote printer. The print driver processes the data that you want to print into a format the printer can understand. If you need to print characters beyond the basic ASCII set (including those used for languages such as Japanese). or NCP). Printer Configuration 265 Figure 34-10. print a test page to ensure the configuration is correct. To make sure the data is not filtered more than once. select a different print driver. After applying the changes. To do this. print a test page to try out this new configuration. Refer to Section 34. and then apply the changes. LPD. Click Back to modify the printer configuration. 34. click Edit. Selecting a Printer Model The recommended print driver is selected based on the printer model selected. You can also configure options such as paper size if you edit the print queue after adding it. the data is filtered multiple times and is converted to a format that the printer can not understand. . and printing a test page. Confirming Printer Configuration The last step is to confirm your printer configuration. If you are configuring a remote printer (IPP. Click Finish to add the print queue if the settings are correct. Refer to Section 34. you need a print driver to process the data that is sent to the printer. SMB.
If you change the print driver or modify the driver options. After adding the printer(s). add it as described in Section 34. To make an IPP printer the default. you should print a test page to test the different configuration. To print a test page. each user should use the GNOME Default Printer Tool. which can be found by selecting Applications (on the Panel) => Preferences => More Preferences => Default Printer. Test Page Options 34. Figure 34-11. . use the system-config-printer command. A IPP browsed queue printer can not be set as the default printer in the Printer Configuration Tool. The printer is removed from the printer list. Printer Configuration 34. In order to set a default printer system-wide. select the printer and click the Delete button on the toolbar. The window contains the current values for the selected printer. The tabbed window shown in Figure 34-12 is displayed. you should print a test page to make sure the printer is functioning properly.2 Adding an IPP Printer and make it the default. the settings can be edited by selecting the printer from the printer list and clicking the Edit button. or the Printer Configuration Tool. then select the appropriate test page from the Test pulldown menu. select the printer from the printer list and click the Default button on the toolbar. Click Apply in the main Printer Configuration Tool window to save the changes and restart the printer daemon. select the printer that you want to try out from the printer list.266 Chapter 34. In order for users to configure a default printer for themselves only.9. Note The GNOME Print Manager no longer sets user level default printers. Printing a Test Page After you have configured your printer. The default printer icon appears in the Default column of the default printer in the list. Make any necessary changes and click OK. Click Apply to save the changes and restart the printer daemon.8. To set the default printer. Modifying Existing Printers To delete an existing printer.
34.3.9. Do not choose it unless problems printing the correct fonts exist.9. Refer to the appropriate section on adding a printer for a description of the options. The queue type of the printer can be changed or just the settings. Editing a Printer 34.2. Printer Configuration 267 Figure 34-12.9.4. . Printer Driver The Printer driver tab shows which print driver is currently being used. different options are displayed. Extra time is required to perform this action. Options vary for each print driver. If it is changed. Common options include: • Prerender Postscript should be selected if characters beyond the basic ASCII set are being sent to the printer. select this option to print Japanese fonts to a non-Japanese printer. click OK to return to the main window. Click Apply to save the change and restart the printer daemon. This option prerenders non-standard PostScript fonts so that they are printed correctly. Click Apply to save the changes and restart the printer daemon. The name of the printer should change in the printer list. After making modifications. click OK to return to the main window. change the value in the Queue name tab. Click Apply to save the change and restart the printer daemon. but they are not printing correctly (such as Japanese characters).1. Depending on which queue type is chosen. For example. Driver Options The Driver options tab displays advanced printer options. If the printer does not support the fonts you are trying to print.Chapter 34. Click OK to return to the main window. Queue Name To rename a printer or change its short description. try selecting this option.9. Queue Type The Queue type tab shows the queue type that was selected when adding the printer and its settings. 34. 34.
Effective Filter Locale defaults to C. If this file is saved. Page Size allows the paper size to be selected. you can merge the files with the following command (as root): /usr/sbin/system-config-printer-tui --Ximport --merge < settings.xml Your configuration is saved to the file settings. select ja_JP. To restore the configuration. If the imported configuration file has a print queue with the same name as an existing print queue on the system. Media Source defaults to Printer default. Issue the following command as root: /sbin/service cups restart . 34. This option is only available if the PostScript driver is used. The file should be saved on a different system before reinstalling. and A4. A3. • • • To modify the driver options. Printer Configuration Also select this option if the printer can not handle PostScript level 3. Change this option to use paper from a different tray. the application creates its own configuration file that is used to create the files in the /etc/cups/ directory. it can be used to restore the printer settings. When creating a backup of the system's configuration files. Click Apply to save the change and restart the printer daemon. US Legal.xml Your printer list then consists of the printers you configured on the system as well as the printers you imported from the saved configuration file.268 Chapter 34. Saving the Configuration File When the printer configuration is saved using the Printer Configuration Tool. After importing the configuration file (with or without the merge command). use the following method to save the printer configuration files.10. If you want to keep your existing configuration and add the configuration in the saved file. the printer configuration is not restored because each time the printer daemon is restarted. type this command as root: /usr/sbin/system-config-printer-tui --Xexport > settings. You can use the command line options to save or restore the Printer Configuration Tool file. The options include US Letter.xml If you already have a configuration file (you have configured one or more printers on the system already) and you try to import another configuration file. Otherwise. This is useful if the printer configuration is deleted. the existing configuration file is overwritten. click OK to return to the main window. If Japanese characters are being printed. it creates a new /etc/printcap file from the Printer Configuration Tool configuration file. To save your printer configuration. or if the same printer configuration is needed on multiple systems. or Convert to PS level 2 in case the printer cannot handle certain PostScript levels. Convert to PS level 1.xml. if Red Hat Enterprise Linux is reinstalled. • GhostScript pre-filtering allows you to select No pre-filtering. type this command as root: /usr/sbin/system-config-printer-tui --Ximport < settings. If the /etc/cups/ directory is saved and restored to the same locations. the print queue from the imported file will override the existing printer. you must restart the printer daemon. accept the default of C. This option converts it to PostScript level 1.
--as-default (Optional) Set this as the default queue. Command Line Configuration If you do not have X installed and you do not want to use the text-based version. --make=make (Required) The IEEE 1284 MANUFACTURER string. Adding a Local Printer To add a printer: system-config-printer-tui --Xadd-local options Options: --device=node (Required) The device node to use.1. Removing a Local Printer A printer queue can also be removed via the command line.11. a name based on the device node (such as "lp0") is used. This method is useful if you want to add a printer from a script or in the %post section of a kickstart installation.Chapter 34. Printer Configuration 269 34. --model=model (Required) The IEEE 1284 MODEL string or (if non is available) the printer model listed in the foomatic database.11. use the following command to start/restart the printer daemon: service cups restart 34. If one is not given. to remove a printer queue: system-config-printer-tui --Xremove-local options Options: --device=node (Required) The device node used such as /dev/lp0. or (if none is available) the printer manufacturer's name as it appears in the foomatic database. in the foomatic database.11.2. you can add a printer via the command line. --name=name (Optional) The name to be given to the new queue. --make=make (Required) The IEEE 1284 MANUFACTURER string or (if none is available) the printer manufacturer's name as it appears. After adding the printer. /dev/lp0. . As root. For example. 34.
Managing Print Jobs When you send a print job to the printer daemon. Figure 34-13. the job number. Printer Configuration (Required) The IEEE 1284 MODEL string. such as printing a text file from Emacs or printing an image from The GIMP.3. Setting the Default Printer To set the default printer. the print job is added to the print spool queue. . the hostname of the system that sent the request. or (if none is available) the printer model as listed in the foomatic database. GNOME Print Manager To change the printer settings. and more. execute the following command (as root): service cups stop 34. click the Printer Manager icon on the panel to start the GNOME Print Manager as shown in Figure 34-13. the username of the person who sent the request. The Printer Configuration Tool is then started.270 --model=model Chapter 34. After removing the printer from the Printer Configuration Tool configuration.11. If you are running a graphical desktop environment. use the following command and specify the queuename: system-config-printer-tui --Xdefault --queue=queuename 34. and you do not want to run the printer daemon anymore. right-click on the icon for the printer and select Properties. restart the printer daemon for the changes to take effect (as root): service cups restart If all printers have been removed. The print spool queue is a list of print jobs that have been sent to the printer and information about each print request. Double-click on a configured printer to view the print spool queue as shown in Figure 34-14.12. such as the status of the request.
Click OK to start printing the file. The window shown in Figure 34-16 is displayed. Also located on the Panel is a Print Manager icon. select it from the list and select Edit => Cancel Documents from the pulldown menu. Printer Configuration 271 Figure 34-14. a printer notification icon may appear in the Panel Notification Area of the desktop panel as shown in Figure 34-15. If there are active print jobs in the print spool. browse to the location of the file and drag and drop it on to the Print Manager icon on the Panel. Figure 34-16. the icon may not be displayed for short print jobs.Chapter 34. To print a file from Nautilus. Figure 34-15. Because it probes for active print jobs every five seconds. List of Print Jobs To cancel a specific print job listed in the GNOME Print Manager. Print Verification Window . Printer Notification Icon Clicking on the printer notification icon starts the GNOME Print Manager and displays a list of current print jobs.
You can not cancel print jobs that were started by other users unless you are logged in as root on the machine to which the printer is attached. The last few lines look similar to the following: Rank Owner/ID active user@localhost+902 Class A Job Files 902 sample. You must have proper permissions to cancel a print job. lprm 902 would cancel the print job in Example 34-1. Note If a printer is not selected. . Sharing a Printer The Printer Configuration Tool's ability to share configuration options can only be used if you are using the CUPS printing system.13.txt. Example of lpq output If you want to cancel a print job. Action => Sharing only shows the system-wide sharing options normally shown under the General tab. By default. Allowing users on a different computer on the network to print to a printer configured for your system is called sharing the printer. 34. To share a configured printer. select the option to make the queue available to other users. You can also print a file directly from a shell prompt. Printer Configuration To view the list of print jobs in the print spool from a shell prompt. the command lpr sample. start the Printer Configuration Tool and select a printer from the list. Then select Action => Sharing from the pulldown menu. type the command lpq. On the Queue tab.txt prints the text file sample. find the job number of the request with the command lpq and then use the command lprm job number .272 Chapter 34. For example.txt Size Time 2050 01:20:46 Example 34-1. For example. printers configured with the Printer Configuration Tool are not shared. The print filter determines what type of file it is and converts it into a format the printer can understand.
If you have a firewall configured on the print server. If you have a firewall configured on the client (the computer sending the print request). especially if the system is directly connected to the Internet. no additional configuration is required for a printer found from IPP browsing. 631. by default. all hosts are allowed to print to the shared printer. There are two options: • Automatically find remote shared queues — Selected by default. When other machines on the network broadcast the queues that they have. Allowing all systems on the network to print to the queue can be dangerous. which is an xinetd service. it must be allowed to send and accept connections on port 631. Figure 34-18. Queue Options After selecting to share the queue. including those not viewable with the Printer Configuration Tool. Allowed Hosts The General tab configures settings for all printers.Chapter 34. it must be able to send and receive connections on the incoming UDP port. the queues are automatically added to the list of printers available to the system. This option does not automatically share the printers configured on the local system. this option enables IPP browsing. It is recommended that this option be changed by selecting the All hosts entry and clicking the Edit button to display the window shown in Figure 34-18. Printer Configuration 273 Figure 34-17. • . Enable LPD protocol — This option allows the printer to receive print jobs from clients configured to use the LPD protocol using the cups-lpd service.
and newsgroups about CUPS.org — GNU/Linux Printing contains a large amount of information about printing in Linux.2.14. The manual page for the class configuration file for CUPS. Figure 34-19.1.cups. System-wide Sharing Options 34. Installed Documentation • map lpr — The manual page for the lpr command that allows you to print files from the command line. • man mpage of paper. all print jobs are accepted from all hosts if they are received from an LPD client.linuxprinting.conf — • man classes. • man cupsd • man cupsd. FAQs. http://www. refer to the following resources. Additional Resources To learn more about printing on Red Hat Enterprise Linux. • man lprm queue. Printer Configuration Warning If this option is enabled.14. — The manual page for the command line utility to remove print jobs from the print — The manual page for the command line utility to print multiple pages on one sheet — The manual page for the CUPS printer daemon. . Useful Websites • • http://www.274 Chapter 34.14. The manual page for the CUPS printer daemon configuration file.conf — 34. 34.org/ — Documentation.
and batch. email is not sent. To schedule one-time tasks. For example.monthly The first four lines are variables used to configure the environment in which the cron tasks are run. To determine if the package is installed.hourly /etc/cron. day of the month. it is not executed. Automated Tasks In Linux.1. Configuring Cron Tasks The main configuration file for cron. and more. monitor the system. use the command /sbin/service crond status. To determine if the service is running. on a specified date. The output of the cron tasks are emailed to the username defined with the MAILTO variable. 35.daily /etc/cron. /etc/crontab. while the PATH variable defines the path used to execute commands. Red Hat Enterprise Linux comes with several automated tasks utilities: cron. at. refer to Section 35. or when the system load average is below a specified number.1. Red Hat Enterprise Linux is pre-configured to run important system tasks to keep the system updated. the vixie-cron RPM package must be installed and the crond service must be running.Chapter 35.weekly /etc/cron. The HOME variable can be used to set the home directory to use when executing commands or scripts. use the rpm -q vixie-cron command.1. Each line in the /etc/crontab file represents a task and has the following format: minute hour day month dayofweek command • minute • hour — any integer from 0 to 59 — any integer from 0 to 23 . Cron assumes that the system is on continuously. The SHELL variable tells the system which shell environment to use (in this example the bash shell). If the MAILTO variable is defined as an empty string (MAILTO=""). and week.2 At and Batch. To use the cron service. 35. contains the following lines: SHELL=/bin/bash PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=root HOME=/ # run-parts 01 * * * * root 02 4 * * * root 22 4 * * 0 root 42 4 1 * * root run-parts run-parts run-parts run-parts /etc/cron. day of the week. Cron Cron is a daemon that can be used to schedule the execution of recurring tasks according to a combination of the time. If the system is not on when a task is scheduled. the slocate database used by the locate command is updated daily. run custom scripts. A system administrator can use automated tasks to perform periodic backups. tasks can be configured to run automatically within a specified period of time. month.
All files in this directory use the same syntax as /etc/crontab. /etc/cron. 6. Whitespace is not permitted in either file. The cron daemon (crond) does not have to be restarted if the access control files are modified. daily. Automated Tasks — any integer from 1 to 31 (must be a valid day if a month is specified) — any integer from 1 to 12 (or the short name of the month such as jan or feb) • month • dayofweek • command — any integer from 0 to 7.2.sh Example 35-1. weekly. 1-4 means the integers 1.d/ directory. login as that user and type the command crontab -e to edit the user's crontab using the editor specified by the VISUAL or EDITOR environment variable. 2.daily/. For example. the /etc/cron. the run-parts script executes the scripts in the /etc/cron. an asterisk (*) can be used to specify all valid values. To create a crontab as a user. Refer to Example 35-1 for examples. or monthly. For example. As shown in the /etc/crontab file.hourly/. # record the memory usage of the system every monday # at 3:30AM in the file /tmp/meminfo 30 3 * * mon cat /proc/meminfo >> /tmp/meminfo # run custom script the first day of every month at 4:10AM 10 4 1 * * /root/scripts/backup.) specifies a list. If a cron task is required to be executed on a schedule other than hourly. 3. When the changes to the crontab are saved. Controlling Access to Cron The /etc/cron.allow and /etc/cron.d/ directory. All user-defined crontabs are stored in the /var/spool/cron/ directory and are executed using the usernames of the users that created them. they are loaded into memory. Crontab Examples Users other than root can configure cron tasks by using the crontab utility. The file uses the same format as /etc/crontab. For example. or monthly basis respectively. 0-59/2 can be used to define every other minute in the minute field. weekly. The forward slash (/) can be used to specify step values. For instance. A hyphen (-) between integers specifies a range of integers. Any lines that begin with a hash mark (#) are comments and are not processed. The cron daemon checks the /etc/crontab file.1. the crontab is stored according to username and written to the file /var/spool/cron/username. A list of values separated by commas (. Step values can also be used with an asterisk. the value */3 can be used in the month field to run the task every third month. where 0 or 7 represents Sunday (or the short name of the week such as sun or mon) >> /tmp/proc or the command to execute a custom script) — the command to execute (the command can either be a command such as ls /proc For any of the above values.weekly/. it can be added to the /etc/cron. 35. and /etc/cron. and 4. 8 indicates those four specific integers. Thus. /etc/cron. daily.monthly/ directories on an hourly. 3. an asterisk for the month value means execute the command every month within the constraints of the other values. . the daemon does not need to be restarted if a crontab file is changed. 4. and the /var/spool/cron/ directory every minute for any changes. The access control files are read each time a user tries to add or delete a cron task.deny files are used to restrict access to cron. The value of an integer can be skipped within a range by following the range with /<integer>.276 • day Chapter 35. The format of both access control files is one username on each line. For example. The files in these directories should be shell scripts. If any changes are found.
If a script is entered. the at command is used to schedule a one-time task at a specific time and the batch command is used to schedule a one-time task to be executed when the systems load average drops below 0. If cron. Refer to Chapter 20 Controlling Access to Services for details on starting the cron service automatically at boot time.deny are not allowed to use cron. or weeks.2. noon — Specifies 12:00 p. Configuring At Jobs To schedule a one-time job at a specific time. it is executed at the specified time the next day. now + 5 days specifies that the command should be executed at the same time five days from now. or /bin/sh (whichever is found first). press [Enter] to go to a blank line and type [Ctrl]-[D]. 04:00 specifies 4:00 a.m. hours. If the time is already past. The year is optional. At and Batch While cron is used to schedule recurring tasks. For example. For more information about the time format. After typing the at command with the time argument. the shell used is the shell set in the user's SHELL environment. only users listed in it are allowed to use cron.1. month-name day year format — For example. Starting and Stopping the Service To start the cron service.8. 35. After typing all the commands.m. press [Enter]. or MM. Multiple commands can be specified by typing each command followed by the [Enter] key. To determine if the service is running. and the cron. followed by the optional date. users listed in cron. MMDDYY. and type [Ctrl]-[D].3.2. To use at or batch. a shell script can be entered at the prompt. the at RPM package must be installed. . 277 If the file cron. 011502 for the 15th day of January in the year 2002. The time must be specified first. Alternatively. and the atd service must be running. use the rpm -q at command.deny file is ignored. To stop the service. 35. MM/DD/YY.YY formats — For example.allow exists. use the command /sbin/service atd status.m.DD. days. It is recommended that you start the service at boot time. 35. the user's login shell. midnight — Specifies 12:00 a. the at> prompt is displayed. January 15 2002 specifies the 15th day of January in the year 2002. pressing [Enter] after each line in the script.allow does not exist. now + time — time is in minutes. read the /usr/share/doc/at-<version>/timespec text file.m. and typing [Ctrl]-[D] on a blank line to exit. type the command at time. regardless of the usernames listed in the access control files. Type the command to execute. The argument time can be one of the following: • • • • • • • HH:MM format — For example.Chapter 35. teatime — Specifies 4:00 p.1. where time is the time to execute the command. Automated Tasks The root user can always use cron. use the command /sbin/service crond start. use the command /sbin/service crond stop. To determine if the package is installed.
the user's login shell. and type [Ctrl]-[D]. Send email to the user when the job has been completed. Usage of the at command can be restricted. Display the time that the job is executed. the output is emailed to the user. refer to 35. Multiple commands can be specified by typing each command followed by the [Enter] key. As soon as the load average is below 0.2. Table 35-1.5 Controlling Access to At and Batch for details. After typing all the commands. If the set of commands or script tries to display information to standard out.2.8.4. press [Enter] to go to a blank line and type [Ctrl][D]. Automated Tasks If the set of commands or script tries to display information to standard out. Alternatively. If the root user executes the atq command.5 Controlling Access to At and Batch for details. and username format. Users can only view their own jobs. For more information.3. hour. Use the command atq to view pending jobs. Refer to Section 35. with each job on a line. date.2. Controlling Access to At and Batch The /etc/at.deny files can be used to restrict access to the at and batch .2. Use the command atq to view pending jobs.2. the set of commands or script is executed. For Section 35. Section 35. If a script is entered. Usage of the batch command can be restricted.2. the output is emailed to the user.2. pressing [Enter] after each line in the script. use the batch command. Configuring Batch Jobs To execute a one-time task when the load average is below 0. Type the command to execute. more information. Each line follows the job number.allow and /etc/at. Refer to Section 35. The atq command displays a list of pending jobs. a shell script can be entered at the prompt. Viewing Pending Jobs To view pending at and batch jobs. use the atq command. job class. the shell used is the shell set in the user's SHELL environment.3 Viewing Pending Jobs for more information. all jobs for all users are displayed. at and batch Command Line Options 35. After typing the batch command. and typing [Ctrl]-[D] on a blank line to exit.2.5. 35. press [Enter]. the at> prompt is displayed.8. or /bin/sh (whichever is found first).2.278 Chapter 35.3 Viewing Pending Jobs for more information. Additional Command Line Options Additional command line options for at and batch include: Option -f -m -v Description Read the commands or shell script from a file instead of specifying them at the prompt. refer to 35.
The access control files are read each time a user tries to execute the at or batch commands. regardless of the access control files. Starting and Stopping the Service To start the at service.deny are not allowed to use at or batch.Chapter 35. 35. and the at. refer to the following resources. man pages in sections 1 and 5 — The man page in section 1 contains an overview of the contains more detailed information about the • crontab crontab file.3. • /usr/share/doc/at-<version>/timespec times that can be specified for cron jobs. only users listed in it are allowed to use at or batch. • at man page — description of at and batch and their command line options. 35. users listed in at. It is recommended that you start the service at boot time. Whitespace is not permitted in either file. Automated Tasks 279 commands.6. The root user can always execute at and batch commands.1. The format of both access control files is one username on each line. Refer to Chapter 20 Controlling Access to Services for details on starting the cron service automatically at boot time. The man page in section 5 contains the format for the file and some example entries.allow exists. 35.deny file is ignored. To stop the service.3. . use the command /sbin/service atd stop. If the file at. If at. Additional Resources To learn more about configuring automated tasks. Installed Documentation • cron man page — overview of cron.2.allow does not exist. use the command /sbin/service atd start. The at daemon (atd) does not have to be restarted if the access control files are modified.
280 Chapter 35. Automated Tasks .
A list of log messages maintained by syslogd can be found in the /etc/syslog. Locating Log Files Most log files are located in the /var/log/ directory. The logrotate package contains a cron task that automatically rotates log files according to the /etc/logrotate. . type the keyword(s) in the Filter for text field. it is configured to rotate every week and keep four weeks worth of previous log files. Some applications such as httpd and samba have a directory within /var/log/ for their log files. These are created when the log files are rotated. and what to look for in log files.Chapter 36. Some log files are controlled by a daemon called syslogd.conf configuration file and the configuration files in the /etc/logrotate.conf configuration file. however. You may notice multiple files in the log file directory with numbers after them. Viewing Log Files Most log files are in plain text format. To view system log files in an interactive. 36. the list might differ from the one shown in Figure 36-1. For example. You can view them with any text editor such as Vi or Emacs. including the kernel. The application only displays log files that exist. how to view log files. This chapter discusses where to find log files. a log file just for security messages.2. go to Applications (the main menu on the panel) => System Tools => System Logs. thus. root privileges are required to read most log files. real-time application.d/ directory. and click Filter. Log Files Log files are files that contain messages about the system. To filter the contents of the log file for keywords. There are different log files for different information. 36. and a log file for cron tasks. Log files are rotated so their file sizes do not become too large. services.1. By default. use the Log Viewer. Log files can be very useful when trying to troubleshoot a problem with the system such as trying to load a kernel driver or when looking for unauthorized log in attempts to the system. and applications running on it. Click Reset to reset the contents. there is a default system log file. To start the application. Some log files are readable by all users on the system. or type the command system-logviewer at a shell prompt.
On the Log Files tab in the Preferences. Figure 36-2. The refresh rate is changed immediately. To refresh the currently viewable file manually. To change the refresh rate. In the Log Files tab. click the up and down arrows beside the refresh rate to change it. Log File Locations . and click Close to return to the main window. Select the log file from the list. the currently viewable log file is refreshed every 30 seconds. Log Viewer By default. Log Files Figure 36-1. and click the Edit button. Click Close to return to the main window. select File => Refresh Now or press [Ctrl]-[R]. the log file locations can be modified.282 Chapter 36. select Edit => Preferences from the pulldown menu. The window shown in Figure 36-2 appears. Type the new location of the log file or click the Browse button to locate the file location using a file selection dialog. Click OK to return to the preferences.
Examining Log Files Log Viewer can be configured to display an alert icon beside lines that contain key alert words and a warning icon beside lines that contain key warning words. The alert icon is displayed to the left of the lines that contains any of the alert words. select Edit => Preferences. and click the Add button in the Log Files tab. To delete a warning word. and click Delete. Alerts To add warning words. and click Delete. Log Files 283 36. select the word from the list. After clicking OK. Figure 36-4. and the location of the log file to add. the file is immediately added to the viewing area.4.Chapter 36. 36.3. To delete an alert word. description. Click the Add button to add an alert word. select Edit => Preferences from the pull-down menu. if the file exists. Figure 36-3. Adding a Log File To add a log file to the list. . Click the Add button to add a warning word. and click on the Warnings tab. Adding a Log File Provide a name. To add alerts words. select Edit => Preferences from the pulldown menu. and click on the Alerts tab. select the word from the list.
Figure 36-5. Warning . Log Files is displayed to the left of the lines that contains any of the warning words.284 The warning icon Chapter 36.
that building a custom kernel is not supported by the Red Hat Global Services Support team. 37. Manually Upgrading the Kernel The Red Hat Enterprise Linux kernel is custom built by the Red Hat kernel team to ensure its integrity and compatibility with supported hardware. Before Red Hat releases a kernel. Tip Use of up2date is highly recommended by Red Hat for installing upgraded kernels. and up2date. The Red Hat Update Agent automatically queries the Red Hat Network servers and determines which packages need to be updated on your machine.1. without using the up2date command. and therefore is not explored in this manual. Overview of Kernel Packages Red Hat Enterprise Linux contains the following kernel packages (some may not apply to your architecture): • kernel • • • — Contains the kernel and the following key features: Uniprocessor support for x86 and Athlon systems (can be run on a multi-processor system. it must first pass a rigorous set of quality assurance tests. the Red Hat Update Agent. but only one processor is utilized) Multi-processor support for all other architectures For x86 systems. For more information on Red Hat Network. only the first 4 GB of RAM is used. including the kernel. This chapter is only useful for those individuals that require manual updating of kernel packages. refer to Chapter 17 Red Hat Network. • kernel-hugemem • — (only for i686 systems) In addition to the options enabled for the kernel package. Red Hat Enterprise Linux kernels are packaged in RPM format so that they are easy to upgrade and verify using the Red Hat Update Agent. use the kernel-hugemem package for x86 systems with over 4 GB of RAM • kernel-devel — Contains the kernel headers and makefiles sufficient to build modules against the kernel package.Chapter 37. or the up2date command. Warning Please note. the key configuration options are as follows: Support for more than 4 GB of RAM (up to 64 GB for x86) .
these files are placed in the /usr/share/doc/kernel-doc-<version>/ directory. For example. Installation of this package provides a reference to the options that can be passed to Linux kernel modules at load time. The first step is to make sure working boot media exists for the system in case a problem occurs. Manually Upgrading the Kernel Note kernel-hugemem is required for memory configurations higher than 16 GB. • kernel-doc — Contains documentation files from the kernel source. • kernel-smp tures: • — Contains the kernel for multi-processor systems.286 Chapter 37. and type the following command at a shell prompt: /sbin/mkbootdisk 'uname -r' . • • • PAE (Physical Address Extension) or 3 level paging on x86 processors that support PAE Support for multiple processors 4GB/4GB split — 4GB of virtual address space for the kernel and almost 4GB for each user process on x86 systems • kernel-hugemem-devel — Contains the kernel headers and makefiles sufficient to build modules against the kernel-hugemem package. If the boot loader is not configured properly to boot the new kernel.src. to create a boot diskette. Preparing to Upgrade Before upgrading the kernel. Various portions of the Linux kernel and the device drivers shipped with it are documented in these files. including all updates.rpm must then be rebuilt locally using the rpmbuild command.redhat. 37. at https://www. Contains utilities that can be used to control the kernel or system hardware. Refer to the latest distribution Release Notes. the system cannot be booted into Red Hat Enterprise Linux without working boot media.com/docs/manuals/enterprise/ for more information on obtaining and installing the kernel source package. take a few precautionary steps. Note The kernel-source package has been removed and replaced with an RPM that can only be retrieved from Red Hat Network. login as root. The following are the key fea- Multi-processor support Support for more than 4 GB of RAM (up to 16 GB for x86) PAE (Physical Address Extension) or 3 level paging on x86 processors that support PAE • • • kernel-smp-devel • kernel-utils — — Contains the kernel headers and makefiles sufficient to build modules against the kernel-smp package.2. This *. By default.
9-5.EL kernel-doc-2. Downloading the Upgraded Kernel There are several ways to determine if an updated kernel is available for the system.6. In the file name. AMD Athlon®.<arch>. The format is kernel-<variant>-<version>. Refer to Section 37. Manually Upgrading the Kernel 287 Tip Refer to the mkbootdisk man page for more options.9-5.3.9-5. and AMD Duron® systems 37. the only required package is the kernel package.6. execute the following command at a shell prompt: rpm -qa | grep kernel The output contains some or all of the following packages. each kernel package contains the architecture for which the package was built.6. Creating bootable media via CD-Rs.9-5.9-5.redhat. The options are as follows: • i686 for Intel® Pentium® II.EL kernel-smp-2.EL kernel-smp-devel-2. Intel® Pentium® III. determine which packages need to be download for the kernel upgrade. For a single processor system. but store it in a safe place just in case.EL kernel-devel-2.6. depending on the system's architecture (the version numbers and packages may differ): kernel-2. Intel® Pentium® 4. Reboot the machine with the boot media and verify that it works before continuing. To determine which kernel packages are installed.1 Overview of Kernel Packages for descriptions of the different packages. the media is not needed.9-5. utils. • Security Errata — Go to the following location for information on security errata.EL kernel-utils-2.6.EL From the output. including kernel upgrades that fix security issues: http://www.rpm.EL kernel-hugemem-devel-2.9-5. and USB flash drives are also supported given the system BIOS also supports it. where <variant> is smp. or so forth.6. Hopefully.Chapter 37.6. CD-RWs. The <arch> is one of the following: • x86_64 • ia64 for the AMD64 architecture for the Intel® Itanium™ architecture for the IBM® eServer™ pSeries™ architecture for the IBM® eServer™ iSeries™ architecture for the IBM® eServer™ zSeries® architecture • ppc64 • ppc64 • s390 for the IBM® S/390® architecture • s390x • x86 variant: The x86 kernels are optimized for different x86 versions.com/apps/support/errata/ • Via Quarterly Updates — Refer to the following location for details: .
a SCSI controller. Refer to Section 37.288 Chapter 37.EL. only do not change the kernel to boot by default. Do not use the -U option. For more information.html • Via Red Hat Network — Download and install the kernel RPM packages. If Red Hat Network was used to download and install the updated kernel.5 Verifying the Initial RAM Disk Image and Section 37.redhat.6. refer to http://www.com/docs/manuals/RHNetwork/. To verify that it was created.5 Verifying the Initial RAM Disk Image for details. and configure the boot loader to boot the new kernel.4 Performing the Upgrade. install the kernel-smp packages as well (the kernel version may vary): rpm -ivh kernel-smp-2. 37.9-5.9-5. this step is performed automatically if the kernel and its associated packages are installed or upgraded from the RPM packages distributed by Red Hat. Issue the following command (the kernel version may vary): rpm -ivh kernel-2. At a shell prompt.. or uses labels to reference partitions in /etc/fstab. the initial RAM disk can be created with the mkinitrd command. The initial RAM disk allows a modular kernel to have access to modules that it might need to boot from before the kernel has access to the device where the modules normally reside.4. an initial RAM disk is needed.<arch>. which creates boot loader problems. Use the -i argument with the rpm command to keep the old kernel.5. On the Red Hat Enterprise Linux architectures other than IBM eServer iSeries.rpm If the system is a multi-processor system.i686. follow the instructions in Section 37.6 Verifying the Boot Loader. thus. To install the kernel manually.rpm The next step is to verify that the initial RAM disk image has been created. Performing the Upgrade After retrieving all of the necessary packages.rpm If the system is i686-based and contains more than 4 GB of RAM.redhat.9-5. since it overwrites the currently installed kernel. use the . continue to Section 37. Important It is strongly recommended that the old kernel is kept in case there are problems with the new kernel. it does not need to be executed manually. Red Hat Network can download the latest kernel. create an initial RAM disk image if needed. upgrade the kernel on the system. Manually Upgrading the Kernel http://www. Red Hat Network automatically changes the default kernel to the latest version. it is time to upgrade the existing kernel. change to the directory that contains the kernel RPM packages and follow these steps.com/apps/support/errata/rhlas_errata_policy. Verifying the Initial RAM Disk Image If the system uses the ext3 file system. as root.EL.<arch>.6. 37. Inc.6. install the kernel-hugemem package built for the i686 architecture as well (the kernel version might vary): rpm -ivh kernel-hugemem-2. However.EL.
0)/grub/splash..img If a separate /boot/ partition was created. which includes all AMD64 systems. The next step is to verify that the boot loader has been configured to boot the new kernel.6.9-1.906_EL ro root=LABEL=/ initrd /initrd-2.6. change the value of the default variable to the title section number for the title section that .Chapter 37.0) # kernel /vmlinuz-version ro root=/dev/hda2 # initrd /initrd-version. it does not configure the boot loader to boot the new kernel by default.906_EL.1.6. This is a crucial step.6.9-1. the system does not boot into Red Hat Enterprise Linux properly. 37.conf contains a title section with the same version as the kernel package just installed (if the kernel-smp or kernel-hugemem package was installed. To configure GRUB to boot the new kernel by default.EL ro root=LABEL=/ initrd /initrd-2. If the boot loader is configured incorrectly. This means that # all kernel and initrd paths are relative to /boot/. x86 Systems All x86 systems use GRUB as the boot loader. Verifying the Boot Loader The kernel RPM package configures the boot loader to boot the newly installed kernel (except for IBM eServer iSeries systems).9-5.9-5. GRUB Confirm that the file /boot/grub/grub. Manually Upgrading the Kernel 289 command ls -l /boot to make sure the initrd-<version>.6 Verifying the Boot Loader for details.6.9-5. To verify that it was created. It is always a good idea to confirm that the boot loader has been configured correctly.6. which is created with the addRamDisk command.gz title Red Hat Enterprise Linux (2. Notice that the default is not set to the new kernel. Refer to Section 37. it does not need to be executed manually. boot the system with the boot media created earlier and try configuring the boot loader again.EL) root (hd0. This step is performed automatically if the kernel and its associated packages are installed or upgraded from the RPM packages distributed by Red Hat. use the command ls -l /boot to make sure the /boot/vmlinitrd-<kernel-version> file was created (the version should match the version of the kernel just installed). If this happens. # root (hd0. However.6.906_EL) root (hd0.6.EL.0) kernel /vmlinuz-2. the paths to the kernel and initrd image are relative to /boot/. a section exists for it as well): # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. On iSeries systems.1. thus.6.xpm.0) kernel /vmlinuz-2.img file was created (the version should match the version of the kernel just installed). Inc. eg. 37.img #boot=/dev/hda default=1 timeout=10 splashimage=(hd0. the initial RAM disk file and vmlinux file are combined into one file. 37.1.img title Red Hat Enterprise Linux (2.9-1.
9-5.EL.img parameters="root=LABEL=/" [old] image=/boot/vmlinuz-2.6.6.EL ramdisk=/boot/initrd-2.9-5. For example.9-1.img read-only append="root=LABEL=/" image=vmlinuz-2.conf as the configuration file. The count starts with 0.6. set default to 0.6. 37. IBM S/390 and IBM eServer zSeries Systems The IBM S/390 and IBM eServer zSeries systems use z/IPL as the boot loader. if the new kernel is the first title section.6.img read-only append="root=LABEL=/" Notice that the default is not set to the new kernel.9-1.6.906_EL.6. which uses /etc/zipl.906_EL ramdisk=/boot/initrd-2.9-1. 37. Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly.9-1. To configure z/IPL to boot the new kernel by default change the value of the default variable to the name of the section that contains the new kernel. Manually Upgrading the Kernel contains the new kernel.img parameters="root=LABEL=/" Notice that the default is not set to the new kernel.6. which uses /boot/efi/EFI/redhat/elilo.3.2.9-5.906_EL label=old initrd=initrd-2. change the value of the default variable to the value of the label for the image section that contains the new kernel. Confirm that this file contains an image section with the same version as the kernel package just installed: prompt timeout=50 default=old image=vmlinuz-2. After modifying the configuration file.conf as the configuration file.9-5. run the following command as root to enable the changes: .EL label=linux initrd=initrd-2. Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly.6.6.906.EL. To configure ELILO to boot the new kernel. The first line of each section contains the name in brackets. Itanium Systems Itanium systems use ELILO as the boot loader. Confirm that the file contains a section with the same version as the kernel package just installed: [defaultboot] default=old target=/boot/ [linux] image=/boot/vmlinuz-2.290 Chapter 37.
6. issue the following command.6.9-5. 2.conf as the configuration file. 37. B. Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly.img append="root=LABEL=/" image=/vmlinux-2.EL label=linux read-only initrd=/initrd-2.9-5. which uses /etc/aboot. IBM eServer iSeries Systems The /boot/vmlinitrd-<kernel-version> file is installed when you upgrade the kernel. issue the command cat /proc/iSeries/mf/side to determine the default side (either A. 37.img append="root=LABEL=/" Notice that the default is not set to the new kernel.6. To change the default kernel to boot either move its image stanza so that it is the first one listed or add the directive default and set it to the label of the image stanza that contains the new kernel. or C). As root.Chapter 37.EL.4. you must use the dd command to configure the system to boot the new kernel: 1.6. As root. Manually Upgrading the Kernel /sbin/zipl 291 Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly.6. IBM eServer pSeries Systems IBM eServer pSeries systems use YABOOT as the boot loader. However.9-5. .6. Confirm that the file contains an image section with the same version as the kernel package just installed: boot=/dev/sda1 init-message=Welcome to Red Hat Enterprise Linux! Hit <TAB> for boot options partition=2 timeout=30 install=/usr/lib/yaboot/yaboot delay=10 nonvram image=/vmlinux--2.EL.5.9-5. where <kernel-version> is the version of the new kernel and <side> is the side from the previous command: dd if=/boot/vmlinitrd-<kernel-version> of=/proc/iSeries/mf/<side>/vmlinux bs=8k Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly. The kernel in the first image is booted by default.EL label=old read-only initrd=/initrd--2.
292 Chapter 37. Manually Upgrading the Kernel .
add the following line to /etc/modules. The module can also be specified manually by editing the module configuration file. When the system is booted with the new hardware. During installation. the installation program decides which modules need to be loaded at boot time. thus. not the kernel. and configures the module for it. detects the new hardware if it is supported.conf: alias eth1 tulip Refer to the Red Hat Enterprise Linux Reference Guide for an alphabetical list of kernel modules and supported hardware for those modules. the system must be configured to load the proper kernel module for the new hardware.conf. If new hardware is added after installation and the hardware requires a kernel module. only a minimal resident kernel is loaded into memory.Chapter 38. 38.1. For example: Module nfs lockd parport_pc lp parport autofs4 i2c_dev Size 218437 63977 24705 12077 37129 23237 11329 Used by 1 2 nfs 1 0 2 parport_pc. Kernel Module Utilities A group of commands for managing kernel modules is available if the module-init-tools package is installed. a kernel module. The command /sbin/lsmod displays a list of currently loaded modules. At boot time. The installation program sets up the dynamic loading mechanism to work transparently. the module configuration file contains the following line: alias eth0 tulip If a second network card is added to the system and is identical to the first card. Use these commands to determine if a module has been loaded successfully or when trying different modules for a piece of new hardware. the hardware on the system is probed. if a system included an SMC EtherPower 10 PCI network adapter. Kernel Modules The Linux kernel has a modular design. is dynamically loaded into memory. For example. /etc/modprobe. Note Video card modules used to display the X Window System interface are part of the xorg-X11 packages. Based on this probing and the information provided by the user. whenever a user requests a feature that is not present in the resident kernel.lp 2 0 . sometimes referred to as a driver. Thereafter. this chapter does not apply to them. the Kudzu program runs.
Kernel Modules 1 i2c_dev 5 nfs. use the -v option. meaning that other modules must be loaded first for it to load. To print to the screen all commands as /sbin/modprobe executes them. By default.6. however. For example: /sbin/modprobe -v e100 Output similar to the following is displayed: /sbin/insmod /lib/modules/2. To load a kernel module. the command /sbin/modprobe e100 loads any module dependencies and then the e100 module. The /sbin/modprobe command checks for these dependencies and loads the module dependencies before loading the specified module. such as the net/ subdirectory for network interface drivers. the command .6.dm_zero. use the /sbin/modprobe command followed by the kernel module name. The /sbin/lsmod output is less verbose and easier to read than the output from viewing /proc/modules.ko Symbol version prefix 'smp_' The /sbin/insmod command also exists to load kernel modules. For example.ko Using /lib/modules/2. the first column is the name of the module.ips.9-5.294 i2c_core sunrpc button battery ac md5 ipv6 ohci_hcd e100 mii floppy sg dm_snapshot dm_zero dm_mirror ext3 jbd dm_mod ips aic7xxx sd_mod scsi_mod 22081 157093 6481 8901 4805 4033 232833 21713 39493 4673 58481 33377 17029 2369 22957 116809 71257 54741 46173 148121 17217 121421 Chapter 38.9-5. and the third column is the use count. To unload kernel modules.EL/kernel/drivers/net/e100.sd_mod For each line. it does not resolve dependencies. Thus.EL/kernel/drivers/net/e100. modprobe attempts to load the module from the /lib/modules/<kernel-version>/kernel/drivers/ subdirectories. The rmmod utility only unloads modules that are not in use and that are not a dependency of other modules in use. use the /sbin/rmmod command followed by the module name. the second column is the size of the module. Some kernel modules have module dependencies. it is recommended that the /sbin/modprobe command be used. For example.dm_mirror 2 0 3 4 sg.aic7xxx.lockd 0 0 0 1 16 0 0 1 e100 0 0 0 0 2 2 1 ext3 6 dm_snapshot. There is a subdirectory for each type of module.
38.modules file at boot time.modules is executed earlier in the boot process. Another useful kernel module utility is modinfo.conf file. and not rc. 38.txt how to compile and use kernel modules. Use the command /sbin/modinfo to display information about a kernel module.3. However. which is given correct settings in the /etc/modprobe. it is sometimes necessary to explicitly force the loading of a module at boot time. which contains various commands to load modules.2.modules should be used. The rc. 38. Persistent Module Loading Kernel modules are usually loaded directly by the facility that requires them. For example. man page — description and list of command line options. man page — description and list of command line options. . • insmod • modprobe • rmmod man page — description and list of command line options. which lists the parameters the module supports.modules # chmod +x /etc/rc.local because rc. Red Hat Enterprise Linux checks for the existence of the /etc/rc. and -p. — • modinfo • /usr/share/doc/kernel-doc-<version>/Documentation/kbuild/modules. man page — description and list of command line options. Installed Documentation • lsmod man page — description and explanation of its output. Kernel Modules /sbin/rmmod e100 295 unloads the e100 kernel module.modules Tip This approach is not necessary for network and SCSI interfaces because they have their own specific mechanisms.3. refer to the modinfo man page (man modinfo). which displays a brief description of the module. the following commands configure loading of the foo module at boot time (as root): # echo modprobe foo >> /etc/rc. Additional Resources For more information on kernel modules and their utilities. The general syntax is: /sbin/modinfo [options] <module> Options include -d. refer to the following resources.1. For a complete list of options.Chapter 38.
html — Linux Loadable Kernel Module HOWTO from the Linux Documentation Project.com/mirrors/LDP/HOWTO/Module-HOWTO/index.3. . Kernel Modules 38.2. Useful Websites • http://www.296 Chapter 38.redhat.
Even if a user does not plan to send email from the system. the system-switch-mail-gnome package must also be installed. Mail Transport Agent Switcher If you select OK to change the MTA. Mail Transport Agent (MTA) Configuration A Mail Transport Agent (MTA) is essential for sending email. or type the command system-switch-mail at a shell prompt (for example. Postfix. The Mail Transport Agent Switcher allows for the selection of either sendmail. If X is not detected. is used to read and compose email. Red Hat Enterprise Linux 4 provides three MTAs: Sendmail. the program starts in graphical mode as shown in Figure 39-1. thus making the changes take place immediately. and Exim. Mozilla Mail. refer to Part III Package Management. Thunderbird. To force Mail Transport Agent Switcher to run in text-mode. For more information on installing RPM packages.Chapter 39. it starts in text-mode. the message is handed off to the MTA. The program automatically detects if the X Window System is running. To start the Mail Transport Agent Switcher. If it is running. If you want to use the graphical version. postfix. . in an XTerm or GNOME terminal). some automated tasks or system programs might use the /bin/mail command to send email containing log messages to the root user of the local system. select Applications (the main menu on the panel) => Preferences => More Preferences => Mail Transport Agent Switcher. sendmail is the default MTA. which sends the message through a series of MTAs until it reaches its destination. and the unselected mail daemons are disabled so that they do not start at boot time. the selected mail daemon is enabled to start at boot time. When a user sends an email from an MUA. If all three are installed. The selected mail daemon is started. or exim as the default MTA for the system. use the command system-switch-mail-nox. Figure 39-1. A Mail User Agent (MUA) such as Evolution. and any other mail daemon is stopped. and Mutt. The system-switch-mail RPM package must be installed to use the text-based version of the Mail Transport Agent Switcher program.
Mail Transport Agent (MTA) Configuration For more information about email protocols and MTAs. .298 Chapter 39. refer to the Red Hat Enterprise Linux Reference Guide.
....................................................VI.................. OProfile ......... 301 41........................................ 307 ...................................... Gathering System Information ..................... System Monitoring System administrators also monitor system performance............................... Red Hat Enterprise Linux contains tools to assist administrators with these tasks.......... Table of Contents 40.................
96 pdflush -10 0 0 0 S 0.0 0.98 init 19 0 0 0 S 0. To prevent it from scrolling off the screen. use the following command: ps ax | grep emacs The top command displays currently running processes and important information about them including their memory and CPU usage.00 pdflush 0 0 0 0 S 0.0 0.14:01:42 up 9 days. Mem: 645712k total. To display the owner of the processes.2 0:00.0 0:00. 0. how your hard drive is partitioned. you should learn how to gather essential system information.3% sy.0 0.10.00 kblockd/0 0 0 0 0 S 0.00 khubd 0 0 0 0 S 0.0 0:01.1.0 0:00. the amount of available hard drive space.0 0:01.0 0:00.01 khelper -10 0 0 0 S 0.0 0. An example of top's output is provided as follows: top . System Processes The ps ax command displays a list of current system processes. This list is a static list.00 scsi_eh_1 To exit top. 613184k used. you can pipe it through less: ps aux | less You can use the ps command in combination with the grep command to see if a process is running. For example.0 0. 0. 2 running.0 0. 0.0 0.98 kswapd0 0 0 0 0 S 0. If you want a constantly updated list of running processes. 1310712k PID 10456 18110 1 2 3 4 5 17 18 27 28 30 29 103 173 174 177 USER root root root root root root root root root root root root root root root root root PR 14 16 16 34 5 5 15 5 15 20 15 12 16 25 23 15 20 average: 0.7 0. The ps output can be long.0 0:00.3 2.10 ksoftirqd/0 -10 0 0 0 S 0. load Tasks: 96 total.00 scsi_eh_0 0 0 0 0 S 0.98 X 0 3032 1052 840 R 0. 0 Cpu(s): 2.0 0. in other words.0 0.0 0. 0. 95.0 0.0 0:00.Chapter 40.3% us.00 kseriod 0 0 0 0 S 0.1 0:00. 0k used.00 ahc_dv_0 0 0 0 0 S 0. it is a snapshot of what was running when you invoked the command. 23:48.0 0:00.0 0. 0. For example.00 aio/0 0 0 0 0 S 0.0 0:00.07 top 0 3036 560 480 S 0. 32528k Swap: 1310712k total.7 158:16. The list is both real-time and interactive.0 0:00. you should know how to find the amount of free memory. 0 zombie 2. 176124k buffers free.07 stopped. along with the processes.0% ni. and what processes are running. 226136k cached NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND -1 31408 17m 4828 S 2.0 0:00. Gathering System Information Before you learn how to configure your system.0% wa.0 0:00. 0. including processes owned by other users.0 0:00.0% si free.0 0.0% hi. 4 users. use top as described below. 94 sleeping. 40. . use the command ps aux.07 events/0 -10 0 0 0 S 0.0 0. press the [q] key.0 0.0 0:00.13. to determine if Emacs is running. This chapter discusses how to retrieve this type of information from your Red Hat Enterprise Linux system using simple commands and a few simple programs.00 kacpid -10 0 0 0 S 0.4% id.
Interactive top commands If you prefer a graphical interface for top. You are prompted to enter the number. The GNOME System Monitor allows you to search for a process in the list of running process as well as to view all processes. To learn more about a process. Description Immediately refresh the display Display a help screen Kill a process. select Applications (the main menu on the panel) => System Tools => System Monitor or type gnome-system-monitor at a shell prompt (such as an XTerm). You are prompted for the process ID and the signal to send to it. Details about the process is displayed at the bottom of the window. To sort by the information in a specific column. select it and click the More Info button. To start it from the desktop. Select the Process Listing tab. click on the name of the column. you can use the GNOME System Monitor. Sort by user. This function is useful for processes that have stopped responding to user input. Command [Space] [h] [k] [n] [u] [M] [P] Table 40-1. refer to the top(1) manual page. The column that the information is sorted by appears in a darker gray color. Sort by CPU usage.302 Chapter 40. . To stop a process. or active processes. For more information. Change the number of processes displayed. Gathering System Information Table 40-1 contains useful interactive commands that you can use with top. select it and click End Process. Sort by memory usage. your processes.
and cached. GNOME System Monitor 40. Choose the System Monitor tab. free. Memory Usage The free command displays the total amount of physical memory and swap space for the system as well as the amount of memory that is used.2. total Mem: 630 -/+ buffers/cache: Swap: 1279 used 536 145 0 free 93 485 1279 shared 0 buffers 172 cached 219 If prefer a graphical interface for free. in kernel buffers. To start it from the desktop. shared. Gathering System Information 303 Figure 40-1. you can use the GNOME System Monitor.Chapter 40. total Mem: 645712 -/+ buffers/cache: Swap: 1310712 used 549720 149020 0 free 95992 496692 1310712 shared 0 buffers 176248 cached 224452 The command free -m shows the same information in megabytes. go to Applications (the main menu on the panel) => System Tools => System Monitor or type gnome-system-monitor at a shell prompt (such as an XTerm). which are easier to read. .
Use the du --help command to see more options. . To view the system's partitions and disk space usage in a graphical format. To view the information in megabytes and gigabytes. there is an entry for /dev/shm. This entry represents the system's virtual memory file system.1M 85M 10% /boot none 316M 0 316M 0% /dev/shm In the list of mounted partitions. The du command displays the estimated amount of space being used by files in a directory. Gathering System Information Figure 40-2. the output looks similar to the following: Filesystem 1K-blocks /dev/mapper/VolGroup00-LogVol00 11675568 /dev/sda1 100691 none 322856 Used Available Use% Mounted on 6272120 9281 0 4810348 86211 322856 57% / 10% /boot 0% /dev/shm By default. this utility shows the partition size in 1 kilobyte blocks and the amount of used and available disk space in kilobytes. The -h argument stands for human-readable format. GNOME System Monitor 40. File Systems The df command reports the system's disk space usage.6G 57% / /dev/sda1 99M 9.304 Chapter 40. the disk usage for each of the subdirectories is displayed in a list. use the command du -hs to see only the grand total for the directory in human-readable format. use the command df -h. on the bottom of the tab under Devices. The grand total for the current directory and subdirectories are also shown as the last line in the list.3. use the GNOME System Monitor tab as shown in Figure 40-2.0G 4. The output looks similar to the following: Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup00-LogVol00 12G 6. If you do not want to see the totals for all the subdirectories. If you type du at a shell prompt. If you type the command df at a shell prompt.
0 01:05.1 00:01. Figure 40-3. you can use the Hardware Browser application to display the hardware that can be probed.0 00:02. Savage 4 (rev 04) Ethernet controller: Intel Corp. Hardware If you are having trouble configuring your hardware or just want to know what hardware is in your system. pointing devices.Chapter 40.1 00:0f. and memory size of a system's video card: 00:00. system devices. it displays your CD-ROM devices. Use the command lspci -v for more verbose information or lspci -vv for very verbose output. Click on the category name in the left menu. and video cards. network devices. . lspci can be used to determine the manufacturer. Gathering System Information 305 40.0 00:0f. model. As shown in Figure 40-3. select Applications (the main menu on the panel) => System Tools => Hardware Browser or type hwbrowser at a shell prompt. To start the program from the desktop.4. diskette drives.0 Host bridge: ServerWorks CNB20LE Host Bridge (rev 06) Host bridge: ServerWorks CNB20LE Host Bridge (rev 06) VGA compatible controller: S3 Inc. 82557/8/9 [Ethernet Pro 100] (rev 08) ISA bridge: ServerWorks OSB4 South Bridge (rev 50) IDE interface: ServerWorks OSB4 IDE Controller USB Controller: ServerWorks OSB4/CSB5 OHCI USB Controller (rev 04) SCSI storage controller: Adaptec AIC-7892P U160/m (rev 02) RAID bus controller: IBM ServeRAID Controller The lspci is also useful to determine the network card in your system if you do not know the manufacturer or model number. For example.0 00:00. and the information is displayed. hard drives and their partitions.0 00:0f.2 01:03. Hardware Browser You can also use the lspci command to list all PCI devices.
40. • /proc/ directory — The contents of the /proc/ directory can also be used to gather more detailed system information. Red Hat. Inc. .5. manual page — type man free to learn more about free and its many options.5.2. manual page — Type man top to learn more about top and its many options. manual page — Type man du to learn more about the du command and its many options. refer to the following resources.306 Chapter 40. Refer to the Red Hat Enterprise Linux Reference Guide for additional information about the /proc/ directory. Additional Resources To learn more about gathering system information. — Includes a chapter on monitoring resources.1. • lspci manual page — Type man lspci to learn more about the lspci command and its many options.5. Related Books • Red Hat Enterprise Linux Introduction to System Administration. Gathering System Information 40. 40. Installed Documentation • ps --help • top — Displays a list of options that can be used with ps. • free • df • du manual page — Type man df to learn more about the df command and its many options.
Use the command opcontrol --reset to clear out the samples from previous runs. system-wide performance monitoring tool. an interrupt is generated. Overview of Tools Table 41-1 provides a brief overview of the tools provided with the oprofile package. • opreport • OProfile accumulates data from multiple runs — OProfile is a system-wide profiler and expects processes to start up and shut down multiple times. overhead) produced by performance monitoring. but be aware of some limitations when using it: • • Use of shared libraries — Samples for code in shared libraries are not attributed to the particular application unless the --separate=library option is used. Converts sample database files from a foreign binary format to the native format for the system. . On a Red Hat Enterprise Linux system. OProfile uses this hardware (or a timer-based substitute in cases where performance monitoring hardware is not present) to collect samples of performance-related data each time a counter generates an interrupt. Command op_help op_import Description Displays available events for the system's processor along with a brief description of each. OProfile OProfile is a low overhead. • 41. the number of L2 cache requests. making it possible to control the amount of detail (and therefore. the data contained in these samples can then be used to generate reports on system-level and application-level performance.1. It uses the performance monitoring hardware on the processor to retrieve information about the kernel and executables on the system. essentially rolls over. such as when memory is referenced. does not associate samples for inline functions' properly — opreport uses a simple address range mechanism to determine which function an address is in. Thus. When the counter value. OProfile does not identify processes that are asleep because they are waiting on locks or for some other event to occur (for example an I/O device to finish an operation). the oprofile RPM package must be installed to use this tool. Inline function samples are not attributed to the inline function but rather to the function the inline function was inserted into. The hardware normally takes the form of one or more counters that are incremented each time an event takes place. These samples are periodically written out to disk.Chapter 41. samples from multiple runs accumulate. OProfile is a useful tool. the interrupt handling is not precise like a divide by zero exception. Only use this option when analyzing a sample database from a different architecture. Non-CPU-limited performance problems — OProfile is oriented to finding problems with CPUlimited processes. Many processors include dedicated performance monitoring hardware. the sample may be recorded on a nearby instruction. and the number of hardware interrupts received. later. Due to the out-of-order execution of instructions by the processor. This hardware makes it possible to detect when certain events happen (such as the requested data not being in cache). Performance monitoring samples are inexact — When a performance monitoring register triggers a sample.
Retrieves profile data. As the opcontrol commands are executed. Refer to Section 41. .308 Command opannotate Chapter 41.6 Understanding /dev/oprofile/ for details about this directory.3 Using opannotate for details. OProfile Description Creates annotated source for an executable if the application was compiled with debugging symbols. The following sections describe how to use the opcontrol utility to configure OProfile. Configuring OProfile Before OProfile can be run. Specifying the Kernel First. selecting to monitor the kernel (or selecting not to monitor the kernel) is required.1 Using opreport for details.2. execute the following command as root: opcontrol --setup --no-vmlinux This command also loads the oprofile kernel module. configure whether OProfile should monitor the kernel. execute the following command as root: opcontrol --setup --vmlinux=/usr/lib/debug/lib/modules/'uname -r'/vmlinux Note The debuginfo package must be installed (which contains the uncompressed kernel) in order to monitor the kernel. the setup options are saved to the /root/. OProfile Commands 41. if it is not already loaded. opcontrol opreport oprofiled Table 41-1. Configures what data is collected.2.5. Refer to Section 41.5. At a minimum. To configure OProfile not to monitor the kernel. All others are optional. 41. if it does not already exist. This is the only configuration option that is required before starting OProfile. Refer to Section 41.2 Configuring OProfile for details. the SMP kernel still must be running so that the oprofile module can be loaded from it. Runs as a daemon to periodically write sample data to disk. Note Even if OProfile is configured not to profile the kernel. and creates the /dev/oprofile/ directory. it must be configured. To monitor the kernel.oprofile/daemonrc file. Refer to Section 41.1.
Processor Default Event for Counter Description . Instead. the number of counters available depends on the processor. OProfile 309 Setting whether samples should be collected within the kernel only changes what data is collected.2. If timer is used.Chapter 41. As shown in Table 41-2. events cannot be set for any processor because the hardware does not have support for hardware performance counters. which are used by OProfile to monitor specific events. Setting Events to Monitor Most processors contain counters. 41. To generate different sample files for the kernel and application libraries. refer to Section 41. If timer is not used as the processor type. The default events monitored are shown in Table 41-3. the events monitored can be changed. the timer interrupt is used for profiling. the counters other than counter 0 are not set to an event by default. timer is used as the processor type if the processor does not have supported performance monitoring hardware. and counter 0 for the processor is set to a time-based event by default. Processor Pentium Pro Pentium II Pentium III Pentium 4 (non-hyper-threaded) Pentium 4 (hyper-threaded) Athlon AMD64 Itanium Itanium 2 TIMER_INT IBM eServer iSeries and pSeries cpu_type Number of Counters 2 2 2 8 4 4 4 4 4 1 1 8 6 8 1 1 i386/ppro i386/pii i386/piii i386/p4 i386/p4-ht i386/athlon x86-64/hammer ia64/itanium ia64/itanium2 timer timer ppc64/power4 ppc64/power5 ppc64/970 IBM eServer S/390 and S/390x IBM eServer zSeries timer timer Table 41-2. If more than one counter exists on the processor. not how or where the collected data is stored.3 Separating Kernel and User-space Profiles. OProfile Processors and Counters Use Table 41-2 to verify that the correct processor type was detected and to determine the number of events that can be monitored simultaneously.2.2.
certain events must be mapped to specific counters.1. Pentium CPU_CLK_UNHALTED II. Pentium III. each event can have a sampling rate set for it. an error message is displayed. If the timer interrupt is used. However. and replace <sample-rate> with the number of events between samples.8 Graphical Interface. a sample rate can also be specified: opcontrol --event=<event-name>:<sample-rate> Replace <sample-rate> with the number of events to wait before sampling again. . The smaller the count. execute the following command: cat /dev/oprofile/cpu_type The events available vary depending on the processor type. a time-based event set is selected. Default Events The number of events that can be monitored at one time is determined by the number of counters for the processor. execute the following command as root (the list is specific to the system's processor type): op_help The events for each counter can be configured via the command line or with a graphical interface. the more frequent the samples. Athlon. To determine the events available for profiling. OProfile Pentium Pro. It creates a sample every 100. a lower count may be needed to capture the event instances.310 Processor Default Event for Counter Description Chapter 41. the timer is set to whatever the jiffy rate is and is not usersettable. on some processors. Sampling Rate By default. If the counter cannot be set to a specific event. refer to Section 41. it is not a one-to-one correlation. When setting the event for the counter. use opcontrol: opcontrol --event=<event-name>:<sample-rate> Replace <event-name> with the exact name of the event from op_help. To determine the number of counters available. For more information on the graphical interface. The sampling rate is the number of events between each sample snapshot. If the cpu_type is not timer. For events that do not happen frequently.2.2. 41. AMD64 Pentium 4 (HT and non-HT) Itanium 2 TIMER_INT ppc64/power4 ppc64/power5 ppc64/970 GLOBAL_POWER_EVENTS CPU_CYCLES (none) CYCLES CYCLES CYCLES The processor's clock is not halted The time during which the processor is not stopped CPU Cycles Sample for each timer interrupt Processor Cycles Processor Cycles Processor Cycles Table 41-3.000 clock cycles per processor. To set the event for each configurable counter via the command line.
2.2. unit masks may also be required to further define the event. To configure OProfile not to count events in kernel mode for a specific counter. opcontrol --event=<event-name>:<sample-rate>:<unit-mask> 41. the hexadecimal values must be combined using a bitwise or operation. kernel mode and user mode information is gathered for each event. OProfile 311 Caution Be extremely careful when setting sampling rates. Unit Masks If the cpu_type is not timer. To configure how the daemon writes to sample files. The values for each unit mask are listed in hexadecimal format.2.Chapter 41. . execute the following command: opcontrol --event=<event-name>:<sample-rate>:<unit-mask>:0 Execute the following command to start profiling kernel mode for the counter again: opcontrol --event=<event-name>:<sample-rate>:<unit-mask>:1 To configure OProfile not to count events in user mode for a specific counter. To specify more than one unit mask. execute the following command as root: opcontrol --separate=<choice> <choice> can be one of the following: • none — do not separate the profiles (default) — generate per-application profiles for libraries — generate per-application profiles for the kernel and kernel modules • library • kernel • all — generate per-application profiles for libraries and per-application profiles for the kernel and kernel modules If --separate=library is used. Sampling too frequently can overload the system. it can separate the kernel and library profile data into separate sample files. Unit masks for each event are listed with the op_help command. Separating Kernel and User-space Profiles By default.2. the sample file name includes the name of the executable as well as the name of the library. execute the following command: opcontrol --event=<event-name>:<sample-rate>:<unit-mask>:<kernel>:0 Execute the following command to start profiling user mode for the counter again: opcontrol --event=<event-name>:<sample-rate>:<unit-mask>:<kernel>:1 When the OProfile daemon writes the profile data to sample files. 41.3. causing the system to appear as if it is frozen or causing the system to actually freeze.
The log file for the daemon is located at /var/lib/oprofile/oprofiled. Saving Data Sometimes it is useful to save samples at a specific time. OProfile 41. it may be useful to gather different samples based on different input data sets. when profiling an executable. opcontrol --save=<name> The directory /var/lib/oprofile/samples/name/ is created and the current sample files are copied to it. If the number of events to be monitored exceeds the number of counters available for the processor. oprofiled.5. oprofiled. Analyzing the Data Periodically. execute the following command. to generate reports that can be further analyzed. Before reading the data. collects the samples and writes them to the /var/lib/oprofile/samples/ directory. execute the following command as root: opcontrol --shutdown 41. The settings in /root/.log. For example.log Daemon started. along with the binaries profiled. is started. saving the sample data to different files each time.100000 The following tools are available to profile the sample data once it has been collected: • opreport • opannotate Use these tools. The OProfile daemon. For example. it periodically writes the sample data to the /var/lib/oprofile/samples/ directory. Starting and Stopping OProfile To start monitoring the system with OProfile. To save the current set of sample files. replacing <name> with a unique descriptive name for the current session.oprofile/daemonrc are used. the samples for the default event on a Pentium III processor for /bin/bash becomes: \{root\}/bin/bash/\{dep\}/\{root\}/bin/bash/CPU_CLK_UNHALTED.4. Profiler running. the OProfile daemon. To stop the profiler. execute the following command as root: opcontrol --start Output similar to the following is displayed: Using log file /var/lib/oprofile/oprofiled. make sure all data has been written to this directory by executing the following command as root: opcontrol --dump Each sample file name is based on the name of the executable. 41.312 Chapter 41.3. multiple runs of OProfile can be used to collect data. .
0.2.77 1 0.1279 libglib-2. OProfile 313 Warning The executable being profiled must be used with these tools to analyze the data.0038 libgthread-2.so.400.0.so.0038 libX11.0.2 17 0.0 Each executable is listed on its own line.so 4 0.0113 libXrender. if the executable being monitored changes and a sample file for the executable exists. Thus.6. If it must change after the data is collected.5.0038 libwnck-1.so. .0.400.0301 libgdk-x11-2. Samples for each executable are written to a single sample file.8 1 0. The following is part of an example output: Profiling through timer interrupt TIMER:0| samples| %| -----------------25926 97.so.0.2.3.so.0715 libXft.400.400.4.1.1.0.0 56 0.0226 libgobject-2.9. The third column is the name of the executable.2.0301 ld-2.5212 no-vmlinux 359 1. it must be backed up.2332 libvte. along with the executable used to create it before replacing the executable with a new version.0.0.3.0038 libpam.0150 libgtk-x11-2. The first column is the number of samples recorded for the executable.4.4.0038 libtermcap.0188 oprofiled 4 0.0113 du 1 0.2445 Xorg 62 0.2 1 0. Samples from each dynamically linked library are also written to a single sample file.Chapter 41.4 Saving Data for details on how to backup the sample file.0150 libpthread-2.0.0. 41.0639 bash 8 0.400.0. Using opreport The opreport tool provides an overview of all the executables being profiled.so.1.0. Refer to Section 41.4.so 34 0.9.2106 libc-2.4.7 19 0.so.so.7 5 0. While OProfile is running.so 8 0.so.13 6 0.7a 1 0.so.so.4. if the existing sample file is needed. The second column is the percentage of samples relative to the total number of samples. the existing sample file is automatically deleted.so. Refer to the opreport man page for a list of available command line options.so.3504 pi 65 0.2 3 0.3.7 1 0. backup the executable used to create the samples as well as the sample files.13 3 0.0038 libcrypto. such as the -r option used to sort the output from the executable with the smallest number of samples to the one with the largest number of samples.0.
For example. To sort the output from the largest number of samples to the smallest (reverse order).000 symbol name __gconv_transform_utf8_internal The first line is a summary for the symbol/executable combination.7857 1.7857 1.7857 1.7857 1.3571 3. the following output is from the command opreport -l -i __gconv_transform_utf8_internal /lib/tls/libc-<version>. <mode> must be one of the following: -l List sample data by symbols. the following is part of the output from running the command opreport -l /lib/tls/libc-<version>.so: samples 12 5 4 3 3 3 3 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 % 21.7857 1.1 getpid memmove msort_with_tmp strcpy strlen vfprintf write The first column is the starting virtual memory address (vma). The first column is the number of samples for the memory symbol.so: samples 12 % 100. The second column is the number of samples for the symbol.5714 3.9286 7. The third column is the symbol name.7857 1.3571 5.5714 1. and the fourth column is the symbol name.5714 3. For example.7857 1.3571 5.7857 1.1429 5.4286 8.5. use -r in conjunction with the -l option. -i <symbol-name> List sample data specific to a symbol name.7857 1.bx _dl_mcount_wrapper_check mbrtowc memcpy _int_realloc _nl_intern_locale_data free strcmp __ctype_get_mb_cur_max __unregister_atfork __write_nocancel _dl_addr _int_free _itoa_word calc_eclosure_iter fopen@@GLIBC_2. .7857 symbol name __gconv_transform_utf8_internal _int_malloc malloc __i686. OProfile 41. Using opreport on a Single Executable To retrieve more detailed profiled information about a specific executable.7857 1.3571 5.get_pc_thunk.5714 3.2.7857 1.7857 1. The second column is the percentage of samples for the memory address relative to the total number of samples for the symbol. use opreport: opreport <mode> <executable> <executable> must be the full path to the executable to be analyzed. The third column is the percentage of samples for this symbol relative to the overall samples for the executable.7857 1.7857 1.314 Chapter 41.
For this utility to work.3333 8.6. the directories /dev/oprofile/0/ and dev/oprofile/1/ exist. Red Hat Enterprise Linux packages are not compiled with this option. the following command displays the type of processor OProfile detected: cat /dev/oprofile/cpu_type A directory exists in /dev/oprofile/ for each counter. For example. For example.3333 8. Use the cat command to display the values of the virtual files in this file system.000 8. if there are 2 counters. the following output is from the command opreport -l -d __gconv_transform_utf8_internal /lib/tls/libc-<version>. By default.Chapter 41.3333 8. . session:<name> /var/lib/oprofile/samples/ directory.3333 8.3333 8.3333 16. For each virtual memory address. The general syntax for opannotate is as follows: opannotate --search-dirs <src-dir> --source <executable> The directory containing the source code and the executable to be analyzed must be specified. Specify the full path to the session or a directory relative to the 41. Refer to the opannotate man page for a list of additional command line options. -x <symbol-name> Exclude the comma-separated list of symbols from the output. Understanding /dev/oprofile/ The /dev/oprofile/ directory contains the file system for OProfile. Using opannotate The opannotate tool tries to match the samples for particular instructions to the corresponding lines in the source code. 41. It also puts in a comment at the beginning of each function listing the total samples for the function.6667 8.3333 8.3333 symbol name __gconv_transform_utf8_internal The data is the same as the -l option except that for each symbol. For example. the executable must be compiled with GCC's -g option. each virtual memory address used is shown.3333 8.5.3. the number of samples and percentage of samples relative to the number of samples for the symbol is displayed. The resulting files generated should have the samples for the lines at the left.so: vma 00a98640 00a98640 00a9868c 00a9869a 00a986c1 00a98720 00a98749 00a98753 00a98789 00a98864 00a98869 00a98b08 samples 12 1 2 1 1 1 1 1 1 1 1 1 % 100. OProfile -d 315 List sample data by symbols with more detail than -l.3333 8.
— The event to monitor. the counter is off and no samples are collected for it.8. samples are collected even if the processor is in user-space. The interface also displays whether the profiler is running and some brief statistics about it. • 41. the services consuming the most processor time can be moved to dedicated systems. Only events available for the specific counter and the specific architecture are displayed. select the counter from the pulldown menu and select the event from the list. the counter is on and samples are being collected for it. if 1. execute the oprof_start command as root at a shell prompt. — If 0. To start it. save them by clicking the Save and quit button.316 Each directory for a counter contains the following files: • count Chapter 41. — Defines which unit masks are enabled for the counter. samples are not collected for the counter event when the processor is in user-space. After changing any of the options. Determine processor usage — The CPU_CLK_UNHALTED event can be monitored to determine the processor load over a given period of time. A brief description of the event appears in the text box below the list. The values of these files can be retrieved with the cat command. • enabled • event — If 0. and the application exits.oprofile/daemonrc. it can also be used by system administrators to perform system analysis. Example Usage While OProfile can be used by developers to analyze application performance. if 1.7. Exiting the application does not stop OProfile from sampling. This data can then be used to determine if additional processors or a faster processor might improve system performance. Graphical Interface Some OProfile preferences can be set with a graphical interface. . The preferences are written to /root/. • kernel • unit_mask • user — If 0. samples are collected even if the processor is in kernel-space. If the system is used for multiple services but is under performing. On the Setup tab. For example: • Determine which applications and services are used the most on a system — opreport can be used to determine how much processor time an application or service uses. samples are not collected for this counter event when the processor is in kernelspace. For example: cat /dev/oprofile/0/count 41. if 1. to set events for the processor counters as discussed in Section 41.2. OProfile — The interval between samples.2 Setting Events to Monitor.
OProfile 317 Figure 41-1.2. no samples are collected for user applications.3 Separating Kernel and User-space Profiles.1 Sampling Rate. OProfile Setup On the right side of the tab. select the Profile kernel option to count events in kernel mode for the currently selected event. To configure OProfile not to monitor the kernel. they are displayed in the Unit Masks area on the right side of the Setup tab.3 Separating Kernel and User-space Profiles.2. If any unit masks are available for the currently selected event. If this option is unselected. Use the Count text field to set the sampling rate for the currently selected event as discussed in Section 41.Chapter 41. If this option is unselected. as discussed in Section 41. On the Configuration tab.2 Unit Masks.2. Select the checkbox beside the unit mask to enable it for the event.2. Select the Profile user binaries option to count events in user mode for the currently selected event. as discussed in Section 41. no samples are collected for the kernel. .2.2. select No kernel image. enter the name and location of the vmlinux file for the kernel to monitor in the Kernel image file text field. as discussed in Section 41. to profile the kernel.
the oprofiled daemon log includes more information. To start OProfile from the graphical interface. click the Flush profiler data button. refer to the following resources. OProfile Figure 41-2. If Per-application kernel samples files is selected. This is equivalent to the opcontrol --separate=library command.html — • oprofile OProfile Manual man page — Discusses opcontrol. click Start profiler. This is equivalent to the opcontrol --separate=kernel command.318 Chapter 41.1.3 Separating Kernel and User-space Profiles. and op_help . Installed Docs • /usr/share/doc/oprofile-<version>/oprofile. OProfile generates per-application profiles for the kernel and kernel modules as discussed in Section 41.5 Analyzing the Data. Exiting the application does not stop OProfile from sampling. This is equivalent to the opcontrol --dump command.9. opannotate. opreport. To stop the profiler.2. To learn more. OProfile generates per-application profiles for libraries.9. 41. If Per-application shared libs samples files is selected. OProfile Configuration If the Verbose option is selected. To force data to be written to samples files as discussed in Section 41. click Stop profiler. Additional Resources This chapter only highlights OProfile and how to configure and use it. 41.
IRC channels.9. .sourceforge. Useful Websites • http://oprofile. mailing lists. and more.net/ — Contains the latest documentation. OProfile 319 41.2.Chapter 41.
OProfile .320 Chapter 41.
105 getfacl. 225 shadow passwords. 224 Hesiod. 231 NFS. 225 LDAP support. 105 setfacl. 208 related books. 161 color depth. 191 /proc/ directory. 275 additional resources. 169 console making files accessible from. 170 /etc/cups/. 103 activating your subscription. 103 retrieving. 304 /etc/auto. 173 /etc/fstab. 272 configuration console access. 233 conventions document. 277 additional resources. 226 user information. 105 mounting file systems with. 67 booting emergency mode.master. 223 Authentication Configuration Tool. 232 enabling. 224 NIS. v adding group. 208 securing. 104 setting access ACLs. 60. 142 /etc/httpd/conf/httpd. 169 /etc/fstab file enabling disk quotas with. 286 boot partition. 251 user. 54 single-user mode. 257 /etc/exports. 225 MD5 passwords. 212 at. 106 archiving with. 277 additional resources. 56 A Access Control Lists (see ACLs) ACLs access ACLs. 231 defining. 56 rescue mode. 170 /etc/auto. 225 command line version. 243 command line options printing from. 279 authconfig (see Authentication Configuration Tool) authentication. 225 Winbind. 105 default ACLs. 250 Apache HTTP Server (see HTTP Configuration Tool) additional resources. 170 Automated Tasks. 224 C CA (see secure server) chage command forcing password expiration with.Index Symbols /dev/oprofile/. ii copying and pasting text when using X. 97 /etc/hosts. 224 Winbind. 232 console access configuring. 306 /var/spool/cron. 257 /etc/sysconfig/dhcpd.master. 224 autofs.conf. 251 chkconfig. 232 disabling. 103 additional resources. 315 /dev/shm. 276 Kerberos support. 103 with Samba. 225 SMB support. 223 authentication. 103 mounting NFS shares with. 213 APXS. 279 configuration file. 279 boot media. 103 on ext3 file systems. vi Cron. 275 . 275 B batch. 223 cache. 224 LDAP. 195 /etc/printcap.
189 options. 99 hard limit. 50 global parameters. 187 Relay Agent. 192 diskless environment. 173 ext2 reverting from ext3. 100 quotacheck command. 50 overview. 192 command line options. 191 stopping the server. 276 crontab.conf. 60 creating. 100 assigning per user. 50 reasons for using. 47. 49 display settings for X. 50 NFS configuration. 49 adding hosts. 187 dhcpd. 188 starting the server. 304 Dynamic Host Configuration Protocol (see DHCP) D date configuration. using to check. running. 119 drag and drop. forcing. 59 features. 187 additional resources. 99 disabling.leases. 192 dhcpd. 100 assigning per group. 304 DHCP. 61 e2label. 171 exports. 92 emergency mode. 100 enabling. 275 CtrlAltDel shutdown. 99 disk storage (see disk quotas) E e2fsck. 98 quotacheck. 101 reporting. 99 management of. 188 dhcpd. 47. 297 expiration of password. 231 CUPS. 192 disk quotas.conf. 101 soft limit. 51 DHCP configuration. 61 ext3 converting from ext2. 192 server configuration. 212 df. 56 Ethernet connection (see network configuration) exim. 97 additional resources.322 example crontabs. vi DSA keys generating. 191 dhcrelay. 191 dhcrelay. 212 du. modifying. 257 parted (see parted) diskless environment. 102 assigning per file system. 98 grace period. 193 client configuration. 276 user-defined tasks. 187 dhcpd. 243 documentation finding installed. 47. 187 shared-network. 191 subnet. 188 group. disabling. 235 dateconfig (see Time and Date Properties Tool) devel package. 50 Network Booting Tool. 59 . 251 exporting NFS file Systems. 100 /etc/fstab. 166 DSOs loading. 97. 97 creating quota files. 188 PXE installations. 191 connecting to.leases.
303 ftp. 270 GNOME System Monitor. 302 GnuPG checking RPM package signatures. 117 group configuration adding groups. 247 groups (see group configuration) floppy.323 F feedback. 196 LogFormat. 294 installation kickstart (see kickstart installations) LVM. 147. 198 . 199 MaxClients. i IPsec host-to-host. 198 modules. 206 HostnameLookups. 305 Hardware Browser. 304 ext2 (see ext2) ext3 (see ext3) LVM (see LVM) NFS (see NFS) findsmb. 270 change printer settings. 197 ErrorDocument. 155 ISDN connection (see network configuration) H hardware viewing. vii file systems. 207 Options. 250 viewing list of groups. 301 insmod. 149 iptables. 207 MaxKeepAliveRequests. 198 ErrorLog. 248 modify users in groups. 251 modify groups for a user. 195 hwbrowser. 305 G getfacl. 207 KeepAliveTimeout. 199 Group. use of. use of. 184 firewall configuration (see Security Level Configuration Tool) floppy group. 305 Hardware RAID (see RAID) hesiod. 199 LogLevel. 199 KeepAlive. 207 TransferLog. 199 User. 198 ServerAdmin. 196 ServerName. 105 GNOME Print Manager. 207 Listen. 206 httpd. 234 free. 196 TimeOut. 302 gnome-system-monitor. 224 HTTP Configuration Tool directives (see HTTP directives) error log. 65 PXE (see PXE installations) software RAID. 148 ipsec-tools. 195 transfer log. 247 groupadd. 234 I information about your system. 249 additional information. 254 filtering list of groups. 250 modifying group properties. 163 HTTP directives DirectoryIndex. 147 network-to-network. 77 Internet connection (see network configuration) introduction.
34 package selection. 239 Keyboard Configuration Tool. 27 boot loader. 1 xconfig. 21 poweroff. 8 include contents of another file. 16 zerombr. 35 basic options. 29 interactive. 27 %post script. 22 format of. 23. 6 diskette-based. 28 saving. 36 firewall configuration. 10 mouse. 28 root password. 14 rootpw. 239 keyboards. 2 bootloader. 2 authconfig. 1 CD-ROM-based. 42 SELinux configuration. 40 authentication options. 13 pre-installation configuration. 27 language. 30 boot loader options. 16 timezone. 10 network. 22 driverdisk. 10 network-based. 293 loading. 16 volgroup. 5 CD-ROM-based. 24 starting. 28 keyboard. 27 kickstart file %include. 24 Kickstart Configurator. 23. 17 install. 32 preview. 17 kickstart installations. 239 configuration. 28 encrypt. 18 part. 8 installation methods. 5 cmdline. 15 shutdown. 24 options.modules. 22 clearpart. 1 file locations. 2 device. 239 kickstart how the file is found. 9 keyboard. 19 auth. 22 diskette-based. 9 langsupport. 2 autopart. 23 LVM. 24 . 27 network configuration. 294 keyboard configuring. 18 package selection specification. 225 kernel downloading. 9 lang. 16 upgrade. 15 skipx. 7 flash-based. 6 creating. 8 interactive. 10 network-based. 12 partition. 27 reboot. 1 halt. 35 installation method selection. 7 firstboot. 30 Display configuration. 21 %pre. 287 large memory support. 39 partitioning. 12 post-installation configuration. 19 raid. 6 firewall. 295 listing. 285 modules. 27 language support.324 K Kerberos. 15 text. 9 logvol. 28 mouse. 22 flash-based. 293 multiple processor support. 36 text mode installation. 28 time zone. 22 file format. 31 software RAID. 14 reboot. 22 installation tree. 295 unload. 285 kernel modules /etc/rc. 41 %pre script. 285 upgrading. 2 partitioning examples. 2 autostep. 294 persistent loading. 15 selinux. 17 %post. 17 what it looks like.
94 physical extent. 71 logical volume group. 43 pxeboot. 24 from CD-ROM #1 with a diskette. network-to-network. 142 managing DNS Settings. 282 refresh rate. 281 Log Viewer alerts. 70 logical volume. 297 starting in text mode. 224. 141 managing hosts. 147 IPsec. 293 monitor settings for dual head. 71 creating physical volumes. 136 overview. 281 examining. 244 settings for X. 281 syslogd. 297 Mail User Agent. 134 logical network devices. 244 mounting NFS file systems. 225 loading kernel modules. 65. 281 viewing. 282 searching. 10 LVM2 explanation of. 143 managing /etc/hosts.325 from a boot CD-ROM. 71 logical volume group. 63 Logical Volume Manager (see LVM) logrotate. 63. 142 modem connection. 68 volume groups. 63 installing automatic partitioning. 281 lpd. 281 (see also Log Viewer) description. 66 creating a logical volume. 24 M Mail Transport Agent (see MTA) Mail Transport Agent Switcher. 281 rotating. 46 pxeos.conf. 63 additional resources. host-to-host. 225 memory usage. 169 mouse how to use. 134 activating. 63 LVM tools and utilities. 68 creating the boot partition. 303 mkfs. 258 lsmod. 67 creating volume groups. 92 mkpart. 91 modem connection (see network configuration) modprobe. 70 with kickstart. 145 DHCP. 132 . 294 modprobe. 63. 297 L LDAP. 64 N neat (see network configuration) Network Administration Tool (see network configuration) Network Booting Tool. 297 Master Boot Record. 297 switching with Mail Transport Agent Switcher. 71 physical volume. 65 explanation of. 132 activating. vi MTA setting default. 297 MUA. 64 configuring LVM during installation. 50 using with PXE installations. 283 locating. 148 ISDN connection. 44 using with diskless environments. 283 filtering. 293 lspci. 53 reinstalling. 132 Ethernet connection. 63. 56 MD5 passwords. 281 logical volume. 293 log files. 43 network configuration device aliases. 135 activating. 133 IPsec. 305 LVM. 281 log file locations.
173 configuration. 174 stopping the server. 315 opcontrol. 312 unit mask. 312 op_help. 236 ntsysv. 316 op_help. 308 separating profiles.. 163 ssh-add. 175 status of the server. 138 activating. 312 saving data. 171 NIS. 175 autofs (see autofs) command line configuration. 164 . 171 starting the server. 164 sftp. 169 diskless environment. 310 O O'Reilly & Associates. 151 saving to file. 163 /etc/ssh/sshd_config. 167 ssh-keygen DSA. 314 oprofiled. 168 opreport (see OProfile) (see OProfile) OProfile. 141 xDSL connection. 169 over TCP.326 PPPoE connection. 167 OpenSSL additional resources. 318 configuring. 171 hostname formats. 163 starting and stopping. 166 RSA Version 1. 166 RSA Version 1 keys generating. 236 ntpd. 312 --vmlinux=. 308 --start. 175. 168 ssh-agent. 307 /dev/oprofile/. 132 token ring connection. 224 NTP configuring. 143 activating. 224 OpenSSH. 313 on a single executable. 174 mounting. 50 exporting. 168 client. 160 DSA keys generating. 167 server. 208 opannotate (see OProfile) opcontrol (see OProfile) OpenLDAP. 139 wireless connection. 140 activating. 308 opannotate. 151 static IP. 144 restoring from file. 165 RSA keys generating. 138 Network Device Control. 166 generating key pairs. 311 oprofiled (see OProfile) oprof_start. 310 setting. 164 scp. 307 reading data. 315 additional resources. 310 overview of tools. Inc. 136 profiles. 165 ssh. 224. 144 Network File System (see NFS) Network Time Protocol (see NTP) NFS /etc/fstab. 169 additional resources. 175 NFS Server Configuration Tool. 308 opreport. 312 log file. 308 --no-vmlinux. 309 monitoring the kernel. 312 starting. 236 ntpd. configuring for. 168 with GNOME. 311 events sampling rate. 166 RSA. 136 activating. 225 openldap-clients. 163 additional resources.
266 text-based application. 91 table of commands. 263 local printer. command line. 272 remote LPD printer. 257 default printer. 89 viewing partition table. 268 Media Source. 260 rename existing printer.327 P Package Management Tool. 71 physical volume. 122 removing packages. 112 with Package Management Tool. 251 forcing expiration of. 266 networked CUPS (IPP) printer. 114 with Package Management Tool. 266 exporting settings. 43 printconf (see printer configuration) printer configuration. 258 LPD printer. 263 local printer. 63. 297 PPPoE. 115 verifying. 270 viewing print spool. 121 installing packages. 91 removing. 268 sharing. 260 Novell NetWare (NCP) printer. 93 resizing. 90 partition table viewing. 119 preserving configuration files. 115 querying. 123 packages dependencies. 116 querying uninstalled. 273 test page. 118 upgrading. 267 Samba (SMB) printer. 272 command line options. 268 setting default printer. 251 PCI devices listing. 259 IPP printer. 266 delete existing printer. 119 finding deleted files from. 269 add a printer. 263 Samba (SMB) printer. 271 Printer Configuration Tool (see printer configuration) printtool . 115 installing. 269 restore configuration. 259 notification icon. 92 labeling e2label. 89 removing partitions. 257 viewing print spool. 268 GhostScript pre-filtering. 117 pam_smbpass. 257 adding CUPS (IPP) printer. 269 remove a printer. 93 resizing partitions. 268 Page Size. 233 parted. 259 JetDirect printer. 118 freshening with RPM. 92 making mkpart. 271 Novell NetWare (NCP) printer. 261 cancel print job. 90 password aging. 123 tips. 270 change printer settings. 263 printing from the command line. 258 managing print jobs. 268 Prerender Postscript. 114 determining file ownership with. 267 edit driver. 182 pam_timestamp. 267 edit existing printer. 91 formating mkfs. 91 overview. 273 system-wide options. 267 Effective Filter Locale. 93 selecting device. 259 JetDirect printer. 268 save configuration. 68 pixels. 268 IPP printer. 268 GNOME Print Manager. 136 Pre-Execution Environment. 272 allowed hosts. 243 postfix. 270 importing settings. 119 removing. 90 partitions creating. 122 locating documentation for. 261 save configuration to file. 270 modifying existing printers. 270 CUPS. 119 obtaining list of files. 89 creating partitions. 305 physical extent. 93 viewing list. 266 driver options.
303 rcp. 47. 74 level 1. 101 quotaoff. 45 boot message. 122 md5sum. 111 additional resources. 117 dependencies. 120 Red Hat Update Agent. 121 installing. 115 querying. 111 determining file ownership with. 114 design goals. 74 level 5. 294 RPM. 50 Network Booting Tool. 43 pxeboot. 80 creating the RAID partitions. 74 levels. 114 with Package Management Tool. 119 documentation with. 77 explanation of. 301 PXE. 167 runlevel 1. 73 Hardware RAID. 118 uninstalling. 43 overview. 77 level 0. 119 querying uninstalled packages. 149 RAID. 120 checking package signatures. 119 tips. 46 pxeos. 117 graphical interface. 56 runlevels. 43 PXE installations. 73 RAM. 116 querying for file list.328 (see printer configuration) processes. 55 resize2fs. 125 registering your subscription. 73 configuring software RAID during installation. 47 setting up the network server. 74 reasons to use. 112 with Package Management Tool. 119 file conflicts resolving. 54 utilities available. 77 creating the mount points. 120 book about. 118 freshen. 43 adding hosts. 243 RHN (see Red Hat Network) rmmod. 47 configuration. 157 Q quotacheck. 61 . 166 RSA Version 1 keys generating. 74 level 4. 115 freshening packages. 123 upgrading. 301 ps. 115 using. 98 quotacheck command checking quota accuracy with. 44 resolution. 117 preserving configuration files. 43 performing. 113 finding deleted files with. 112 verifying. 43 DHCP configuration. 73 Software RAID. custom. 125 Red Hat Package Manager (see RPM) Red Hat RPM Guide. v rescue mode definition of. 115 GnuPG. 80 creating the RAID devices. 100 R racoon. 100 quotaon. 147. 117 website. 120 RSA keys generating. 73 installing creating the boot partition. 164 Red Hat Network.
220 websites. 155 saving. 157 security level (see Security Level Configuration Tool) Security Level Configuration Tool enabling and disabling. 88 LVM2 creating. 213 security explanation of. 87 removing. 215 testing. 217 moving it after an upgrade. 183 pam_smbpass. 85 explanation of. 183 mounting. 56 SMB. 211 key generating. 220 security. v swap space. 183 Software RAID (see RAID) ssh (see OpenSSH) ssh-add. 184 graphical configuration. 155 trusted services. 219 connecting to. 85 expanding. 155 trusted devices. 214 URLs. 184 smbclient. 183 syncing passwords with passwd. 213 upgrading from. 182 stopping the server. 221 certificate authorities. 214 self-signed.conf.conf. 218 test vs. 168 with GNOME. 178 managing Samba users. 86 reducing. 179 list of active connections. 214 pre-existing. 220 URLs for. 180 configuring server settings. 220 explanation of security. 231 single-user mode. 104 Setup Agent via Kickstart. 154 sendmail. 181 scp (see OpenSSH) secure server accessing. 182 with Windows NT 4. 2000. 159 setfacl. 177 smb. 183 status of the server. 177. 157 Services Configuration Tool. 177 smbclient. 181 default. signed vs. 168 ssh-agent. 86.0. 177 share connecting to via the command line. 155 setting custom ports. 220 books. 213 installing.329 S Samba. 154 iptables service. 73 subscription registration. 7 sftp (see OpenSSH) shadow passwords. 225 smb. 215 choosing a CA. 85 creating. 177 encrypted passwords. 220 providing a certificate for. 87 syslogd. 85 file creating. 182 reasons for using. 184 connecting to with Nautilus. 211 port numbers. 215 packages. 185 configuration. 167 star. 182 findsmb. 304 . 177 additional resources. 86 extending. 105 striping RAID fundamentals. ME. 297 services controlling access to. 184 starting the server. 85 removing. 88 recommended size. 225 shutdown disablingCtrlAltDel . 87 moving. 177. 215 creation of request. and XP. 184 smbstatus. 177 adding a share. 281 system analysis OProfile (see OProfile) system information file systems. self-signed.
249 command line configuration. 301 tune2fs converting to ext3 with. 43. 53 reinstalling the boot loader. 250 passwd. 131. 247 adding users to groups. 60 reverting to ext2 with. 305 memory usage. 244 volume group. 61 U user configuration adding users. 301 system recovery. 301 currently running. 239 system-config-kickstart (see Kickstart Configurator) system-config-mouse (see Mouse Configuration Tool) system-config-netboot. 47. 249 modify groups for a user. 249 changing password. 158 telinit. 214 video card settings for dual head. 151 system-config-packages (see Package Management Tool) system-config-printer (see printer configuration) system-config-securitylevel (see Security Level Configuration Tool) system-config-time (see Time and Date Properties Tool) system-config-users (see user configuration and group configuration) system-logviewer (see Log Viewer) system-switch-mail (see Mail Transport Agent Switcher) system-switch-mail-nox (see Mail Transport Agent Switcher) timetool (see Time and Date Properties Tool) token ring connection (see network configuration) top. 249 additional information. 56 unable to boot into Red Hat Enterprise Linux. 145. 236 time zone configuration. 70 T TCP wrappers. 163 tftp. 250 useradd. 249 viewing list of users. 249 setting user account expiration. 249 changing home directory. 247 locking user accounts. 304 gathering. 63 volume groups. 235 synchronize with NTP server. 158 telnet.330 /dev/shm. 247 User Manager (see user configuration) useradd command user account creation using. 43 system-config-network (see network configuration) system-config-network-cmd. 251 password expiration. 53 hardware/software problems. 248 password forcing expiration of. 237 . 244 settings for X. 250 users (see user configuration) V VeriSign using existing certificate. 249 changing login shell. 303 processes. 53 system-config-authentication (see Authentication Configuration Tool) system-config-date (see Time and Date Properties Tool) system-config-display (see X Configuration Tool) system-config-httpd (see HTTP Configuration Tool) system-config-keyboard. 53 common problems. 254 changing full name. 250 filtering list of users. 248 modifying users. 53 forgetting the root password. 49 time configuration. 301 hardware.
331 W Windows file and print sharing. 181 Windows ME connecting to shares using Samba. 244 X Window System configuration. 224 .0 connecting to shares using Samba. 177 Windows 2000 connecting to shares using Samba. 181 Windows 98 connecting to shares using Samba. 181 Windows NT 4. 158 Y ypbind. 181 X X Configuration Tool display settings. 243 dual head display settings. 243 xDSL connection (see network configuration) xinetd. 181 Windows XP connecting to shares using Samba. 244 hardware settings.
Primary Writer/Maintainer of the Red Hat Enterprise Linux Installation Guide for the IBM® POWER Architecture. The Red Hat Localization Team consists of the following people: Amanpreet Singh Alam — Punjabi translations Jean-Paul Aubry — French translations David Barzilay — Brazilian Portuguese translations Runa Bhattacharjee — Bengali translations Chester Cheng — Traditional Chinese translations Verena Fuehrer — German translations Kiyoto Hashida — Japanese translations N. Itanium™. Contributing Writer to the Red Hat Cluster Suite Configuring and Managing a Cluster Mark Johnson — Primary Writer/Maintainer of the Red Hat Desktop Deployment Guide. The DocBook SGML files are written using Emacs with the help of PSGML mode. Contributing Writer of Red Hat Network Documentation Lucy Ringland — Red Hat Enterprise Linux Documentation Editor. The HTML and PDF formats are produced using custom DSSSL stylesheets and custom jade wrapper scripts. and Intel® Extended Memory 64 Technology (Intel® EM64T) Karsten Wade — Primary Writer/Maintainer of the Red Hat SELinux Guide. important. Contributing Writer to the Red Hat Enterprise Linux System Administration Guide Paul Kennedy — Primary Writer/Maintainer of the Red Hat GFS Administrator's Guide. and Intel® Extended Memory 64 Technology (Intel® EM64T). Co-writer/Co-maintainer of the Red Hat Enterprise Linux Security Guide. Primary Writer/Maintainer of the Red Hat Enterprise Linux Installation Guide for the IBM® S/390® and IBM® eServer™ zSeries® Architectures John Ha — Primary Writer/Maintainer of the Red Hat Cluster Suite Configuring and Managing a Cluster. Primary Writer/Maintainer of the Release Notes. They may be freely redistributed with the Red Hat documentation. caution. Garrett LeSage created the admonition graphics (note. Contributing Writer to the Red Hat Enterprise Linux System Administration Guide Andrius T.1 format. Jayaradha — Tamil translations Michelle Jiyeen Kim — Korean translations Yelitza Louze — Spanish translations Noriko Mizumoto — Japanese translations . Bailey — Primary Writer/Maintainer of the Red Hat Enterprise Linux Introduction to System Administration. Contributing Writer of Red Hat Network documentation Melissa Goldin — Primary Writer/Maintainer of the Red Hat Enterprise Linux Step By Step Guide. Benokraitis — Primary Writer/Maintainer of the Red Hat Enterprise Linux Reference Guide. AMD64. Contributing Writer to the Red Hat Enterprise Linux Installation Guide for x86. Maintainer of custom DocBook stylesheets and scripts Edward C. Moore — Primary Writer/Maintainer of the Red Hat Enterprise Linux Installation Guide for x86.Colophon The manuals are written in DocBook SGML v4. Itanium™. The Red Hat Product Documentation Team consists of the following people: Sandra A. AMD64. Co-writer/Co-maintainer of the Red Hat Enterprise Linux Security Guide. tip. and warning).
334 Ankitkumar Rameshchandra Patel — Gujarati translations Rajesh Ranjan — Hindi translations Nadine Richter — German translations Audrey Simons — French translations Francesco Valente — Italian translations Sarah Wang — Simplified Chinese translations Ben Hung-Pin Wu — Traditional Chinese translations Tongjie Tony Fu — Simplified Chinese Translations Manuel Ospina — Spanish Translations .