FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to data loss and, more particularly, to techniques for print monitoring. 
     BACKGROUND OF THE DISCLOSURE 
     Modern general-purpose computing systems present a variety of challenges for data loss prevention. It can be difficult to limit the exposure of certain types of data when hundreds of different applications may be available for use on a particular system, each one a potential vector for data loss. 
     Printing is one avenue by which sensitive data may be extracted from a system. A conventional method to prevent sensitive data printing is to monitor each application to determine if it initiates a printing process. However, this potentially requires a hook into each application and can be thwarted if any single application is missed by the monitoring. 
     A loss prevention agent can avoid the problem of having to monitor hundreds of applications if, instead, it can monitor a print management system While such central monitoring methods are known for the WINDOWS operating system, no such monitoring system has previously been developed for a Common UNIX Printing System (CUPS) used by MAC OS X and various Linux platforms. 
     In view of the foregoing, it may be understood that significant problems and shortcomings associated with traditional print monitoring methods may be alleviated in some circumstances by a method for monitoring a CUPS printing system. 
     SUMMARY OF THE DISCLOSURE 
     Techniques for print monitoring are disclosed. In one embodiment, the techniques may be realized as a method including monitoring a spool directory associated with a printing system; identifying, for a print job file, a file management call that is made before the print job file is submitted to a printer driver to carry out a print job; blocking the file management call; analyzing the print job file for sensitive data; in response to determining that the print job file does not include sensitive data, re-initiating the file management call for the print job file; and submitting the print job file to a printer driver to carry out a print job. 
     In accordance with other aspects of this embodiment, the method may further include identifying, for a second print job file, a file management call that is made before the second print job file is submitted to a printer driver to carry out a second print job; blocking the file management call for the second print job file; analyzing the second print job file for sensitive data; and, in response to determining that the second print job file includes sensitive data, deleting the second print job file such that the printer driver does not carry out the second print job. 
     In accordance with further aspects of this embodiment, the method may further include displaying an alert notifying a user that the second print job has been blocked. 
     In accordance with further aspects of this embodiment, the method may further include collecting data from the second print job file and at least one additional file in the spool directory regarding the second print job and recording the collected data in an event log. 
     In accordance with other aspects of this embodiment, the printing system may be a CUPS printing system. 
     In accordance with another embodiment, the techniques may be realized as an article of manufacture including at least one processor readable storage medium and instructions stored on the at least one medium. The instructions may be configured to be readable from the at least one medium by at least one processor and thereby cause the at least one processor to operate so as to carry out any and all of the steps in the above-described method. 
     In accordance with another embodiment, the techniques may be realized as a system comprising one or more processors communicatively coupled to a network; wherein the one or more processors are configured to carry out any and all of the steps described with respect to any of the above embodiments. 
     The present disclosure will now be described in more detail with reference to particular embodiments thereof as shown in the accompanying drawings. While the present disclosure is described below with reference to particular embodiments, it should be understood that the present disclosure is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other fields of use, which are within the scope of the present disclosure as described herein, and with respect to which the present disclosure may be of significant utility. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to facilitate a fuller understanding of the present disclosure, reference is now made to the accompanying drawings, in which like elements are referenced with like numerals. These drawings should not be construed as limiting the present disclosure, but are intended to be illustrative only. 
         FIG. 1  shows a block diagram depicting a network architecture in accordance with an embodiment of the present disclosure. 
         FIG. 2  shows a block diagram depicting a computer system in accordance with an embodiment of the present disclosure. 
         FIG. 3  shows a block diagram illustrating a print server including a DLP agent for print monitoring in accordance with an embodiment of the present disclosure. 
         FIG. 4  shows a method for print monitoring in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     A loss prevention agent monitors the content of the directory where print files are created and managed before being sent to the printer driver. The agent interrupts the print call and determines whether a print file includes sensitive data, only allowing files without such data to be passed to the driver. Files in the directory related to the print file can be identified and analyzed to determine metadata associated with the print job. 
       FIG. 1  shows a block diagram depicting a network architecture  100  in accordance with an embodiment of the present disclosure.  FIG. 1  is a simplified view of network architecture  100 , which may include additional elements that are not depicted. Network architecture  100  may contain client systems  110 ,  120  and  130 , as well as servers  140 A- 140 N (one or more of each of which may be implemented using computer system  200  shown in  FIG. 2 ). Client systems  110 ,  120  and  130  may be communicatively coupled to a network  150 . Server  140 A may be communicatively coupled to storage devices  160 A( 1 )-(N), and server  140 B may be communicatively coupled to storage devices  160 B( 1 )-(N). Servers  140 A and  140 B may be communicatively coupled to a SAN (Storage Area Network) fabric  170 . SAN fabric  170  may support access to storage devices  180 ( 1 )-(N) by servers  140 A and  140 B, and by client systems  110 ,  120  and  130  via network  150 . 
     With reference to computer system  200  of  FIG. 2 , modem  247 , network interface  248 , or some other method may be used to provide connectivity from one or more of client systems  110 ,  120  and  130  to network  150 . Client systems  110 ,  120  and  130  may access information on server  140 A or  140 B using, for example, a web browser or other client software (not shown). Such a client may allow client systems  110 ,  120  and  130  to access data hosted by server  140 A or  140 B or one of storage devices  160 A( 1 )-(N),  160 B( 1 )-(N), and/or  180 ( 1 )-(N). 
     Networks  150  and  190  may be local area networks (LANs), wide area networks (WANs), the Internet, cellular networks, satellite networks, or other networks that permit communication between clients  110 ,  120 ,  130 , servers  140 , and other devices communicatively coupled to networks  150  and  190 . Networks  150  and  190  may further include one, or any number, of the exemplary types of networks mentioned above operating as a stand-alone network or in cooperation with each other. Networks  150  and  190  may utilize one or more protocols of one or more clients or servers to which they are communicatively coupled. Networks  150  and  190  may translate to or from other protocols to one or more protocols of network devices. Although networks  150  and  190  are each depicted as one network, it should be appreciated that according to one or more embodiments, networks  150  and  190  may each comprise a plurality of interconnected networks. 
     Storage devices  160 A( 1 )-(N),  160 B( 1 )-(N), and/or  180 ( 1 )-(N) may be network accessible storage and may be local, remote, or a combination thereof to server  140 A or  140 B. Storage devices  160 A( 1 )-(N),  160 B( 1 )-(N), and/or  180 ( 1 )-(N) may utilize a redundant array of inexpensive disks (“RAID”), magnetic tape, disk, a storage area network (“SAN”), an internet small computer systems interface (“iSCSI”) SAN, a Fibre Channel SAN, a common Internet File System (“CIFS”), network attached storage (“NAS”), a network file system (“NFS”), optical based storage, or other computer accessible storage. Storage devices  160 A( 1 )-(N),  160 B( 1 )-(N), and/or  180 ( 1 )-(N) may be used for backup or archival purposes. Further, storage devices  160 A( 1 )-(N),  160 B( 1 )-(N), and/or  180 ( 1 )-(N) may be implemented as part of a multi-tier storage environment. 
     According to some embodiments, clients  110 ,  120 , and  130  may be smartphones, PDAs, desktop computers, laptop computers, servers, other computers, or other devices coupled via a wireless or wired connection to network  150 . Clients  110 ,  120 , and  130  may receive data from user input, a database, a file, a web service, and/or an application programming interface. In some implementations, clients  110 ,  120 , and  130  may specifically be network-capable mobile devices such as smartphones or tablets. 
     Servers  140 A and  140 B may be application servers, archival platforms, backup servers, network storage devices, media servers, email servers, document management platforms, enterprise search servers, or other devices communicatively coupled to network  150 . Servers  140 A and  140 B may utilize one of storage devices  160 A( 1 )-(N),  160 B( 1 )-(N), and/or  180 ( 1 )-(N) for the storage of application data, backup data, or other data. Servers  140 A and  140 B may be hosts, such as an application server, which may process data traveling between clients  110 ,  120 , and  130  and a backup platform, a backup process, and/or storage. According to some embodiments, servers  140 A and  140 B may be platforms used for backing up and/or archiving data. One or more portions of data may be backed up or archived based on a backup policy and/or an archive applied, attributes associated with the data source, space available for backup, space available at the data source, or other factors. 
     According to some embodiments, clients  110 ,  120 , and  130  may contain one or more portions of software for implementation of data loss prevention such as, for example, data loss prevention (DLP) agent  154 . Further, one or more portions of the DLP agent  154  may reside at a network centric location. For example, server  140 A may be a server, a firewall, a gateway, or other network element that may perform one or more actions to support management of system and network security elements. According to some embodiments, network  190  may be an external network (e.g., the Internet) and server  140 A may be a gateway or firewall between one or more internal components and clients and the external network. According to some embodiments, analysis and approval of resource references including DLP agent  154  may be implemented as part of a cloud computing environment. 
       FIG. 2  shows a block diagram of a computer system  200  in accordance with an embodiment of the present disclosure. Computer system  200  is suitable for implementing techniques in accordance with the present disclosure. Computer system  200  may include a bus  212  which may interconnect major subsystems of computer system  200 , such as a central processor  214 , a system memory  217  (e.g. RAM (Random Access Memory), ROM (Read Only Memory), flash RAM, or the like), an Input/Output (I/O) controller  218 , an external audio device, such as a speaker system  220  via an audio output interface  222 , an external device, such as a display screen  224  via display adapter  226 , serial ports  228  and  230 , a keyboard  232  (interfaced via a keyboard controller  233 ), a storage interface  234 , a printer  237  operative to receive data and/or images for printing, a host bus adapter (HBA) interface card  235 A operative to connect with a Fibre Channel network  290 , a host bus adapter (HBA) interface card  235 B operative to connect to a SCSI bus  239 , and an optical disk drive  240  operative to receive an optical disk  242 . Also included may be a mouse  246  (or other point-and-click device, coupled to bus  212  via serial port  228 ), a modem  247  (coupled to bus  212  via serial port  230 ), network interface  248  (coupled directly to bus  212 ), power manager  250 , and battery  252 . 
     Bus  212  allows data communication between central processor  214  and system memory  217 , which may include read-only memory (ROM) or flash memory (neither shown), and random access memory (RAM) (not shown), as previously noted. The RAM may be the main memory into which the operating system and application programs may be loaded. The ROM or flash memory can contain, among other code, the Basic Input-Output system (BIOS) which controls basic hardware operation such as the interaction with peripheral components. Applications resident with computer system  200  may be stored on and accessed via a computer readable medium, such as a hard disk drive (e.g., fixed disk  244 ), an optical drive (e.g., optical drive  240 ), a printer  237 , a removable disk unit (e.g., Universal Serial Bus drive), or other storage medium. According to some embodiments, DLP agent  154  may be resident in system memory  217 . 
     Storage interface  234 , as with the other storage interfaces of computer system  200 , can connect to a standard computer readable medium for storage and/or retrieval of information, such as a fixed disk drive  244 . Fixed disk drive  244  may be a part of computer system  200  or may be separate and accessed through other interface systems. Modem  247  may provide a direct connection to a remote server via a telephone link or to the Internet via an internet service provider (ISP). Network interface  248  may provide a direct connection to a remote server via a direct network link to the Internet via a POP (point of presence). Network interface  248  may provide such connection using wireless techniques, including digital cellular telephone connection, Cellular Digital Packet Data (CDPD) connection, digital satellite data connection or the like. 
     Many other devices or subsystems (not shown) may be connected in a similar manner (e.g., document scanners, digital cameras and so on). Conversely, all of the devices shown in  FIG. 2  need not be present to practice the present disclosure. The devices and subsystems can be interconnected in different ways from that shown in  FIG. 2 . Code to implement the present disclosure may be stored in computer-readable storage media such as one or more of system memory  217 , fixed disk  244  or optical disk  242 . Code to implement the present disclosure may also be received via one or more interfaces and stored in memory. The operating system provided on computer system  200  may be MS-DOS®, MS-WINDOWS®, OS/2®, OS X®, UNIX®, Linux®, or another known operating system. 
     Power manager  250  may monitor a power level of battery  252 . Power manager  250  may provide one or more APIs (Application Programming Interfaces) to allow determination of a power level, of a time window remaining prior to shutdown of computer system  200 , a power consumption rate, an indicator of whether computer system is on mains (e.g., AC Power) or battery power, and other power related information. According to some embodiments, APIs of power manager  250  may be accessible remotely (e.g., accessible to a remote backup management module via a network connection). According to some embodiments, battery  252  may be an Uninterruptable Power Supply (UPS) located either local to or remote from computer system  200 . In such embodiments, power manager  250  may provide information about a power level of an UPS. 
       FIG. 3  shows an example of a print server  300 , which may be any client device or server as described above. Notably, the print server  300  includes a DLP agent  302  for data loss prevention and a print daemon  304  for managing print jobs associated with a printer. The print daemon  304  is configured to manage the printer in accordance with a Common UNIX Printing System (CUPS) protocol, which includes the use of a spool directory  306  in which print files are stored. 
     In one implementation, the print server  300  receives a print instruction and passes it to the print daemon  304 , which translates the request into an intermediate file that is temporarily stored in the spool directory  306 . As shown in  FIG. 3 , the intermediate file  308  named “00059” is stored in the spool directory  306  along with a cache file  310 , a control file  312 , and a set of print job files  314  each of which represent previously completed print jobs in the history of the print server  300 . After updating the cache and control files  310 ,  312  with information about the new job, the intermediate file  308  is renamed according to the naming scheme for the print job files, and the renamed file is then passed to the printer driver for printing. 
     To avoid the printing of sensitive data, the DLP agent includes the capability of identifying and intercepting sensitive data before it can be printed. A spool monitor module  316  monitors the creation and modification of files in the spool directory  306 . It detects when an intermediate file  308  is created in the directory  306 . The print daemon  304  then generates a call to the underlying file management system to rename the intermediate file as a print job file, and this call is intercepted by a call intercept module  318  of the DLP agent  302 . Rather than being renamed and sent to the print driver, the file is instead submitted to a content analysis module  320 . 
     The content analysis module  320  may use any set of methods known in the art to detect sensitive data in the print job file. In some implementations, the file may be a PDF or Post-Script file. Text recognition algorithms may be used if necessary. In some implementations, the format of the data may be used to identify it as sensitive data (such as personnel or medical records). In some information, particular content (such as a list of key words associated with non-public projects) may be used to identify sensitive data. Any method for analyzing a file to determine the presence or absence of sensitive data may be used by the content analysis module  320  as appropriate to the print file. 
     If the content analysis module  320  determines that the file does not include sensitive data, then the intercepted call is allowed to proceed as normal. The print job file is renamed and the print job data is sent to the printer driver for printing. If the content analysis module  320  determines that the file does include sensitive data, then the intercepted call is halted and the file is deleted rather than being renamed. Thus, no print job data is sent to the printer driver and the sensitive information is not printed. 
     In some implementations, the DLP agent may include an alert module  322  that generates an alert whenever sensitive information is intercepted and printing is prevented. The alert module  322  may, using the job identification number from the name of the print job file, collect both data and metadata regarding the prevented print job. In some implementations, information may be collected from associated cache and/or control files produced as part of the spooling process for the print job. The DLP agent  302  may record any of the collected information in an event log and may provide some or all of this information in an alert which is displayed to the user when the print job is prevented. 
       FIG. 4  illustrates a method  400  for print monitoring by a data loss prevention agent. The agent monitors the spool directory in which print job files are first created and then renamed under the CUPS print system ( 302 ). In some implementations, the monitoring may occur through the use of any appropriate framework, such as a file system driver. As described above, the agent may monitor the creation of any file in the directory and may specifically identify the creation of intermediate print files which are then renamed before being submitted to the print driver for printing. 
     Upon identifying a rename call for an intermediate file, the DLP agent intercepts and blocks the rename call, thus interrupting the print process ( 404 ). Blocking the call prevents the file from being renamed and submitted to the print driver, and therefore prevents the print job from completing unless the agent later reinitiates the job. 
     While the print job is blocked from proceeding, the agent analyzes the print file to identify sensitive data ( 406 ). Sensitive data may be identified by any method known in the art, which may include identifying the formatting of any text included in the data and may also include matching the data against data known to be sensitive. The agent may also take other factors into account; for example, the identity of the user, the computer system originating the print request, the particular printer designated for carrying out the request, and even time and date information may potentially impact whether the data associated with a particular print job is considered to be too sensitive to print or allowed to be printed. 
     If the agent determines that the print file does not include sensitive data (“no” from  408 ), then the print job is allowed to proceed as normal ( 410 ). In some embodiments, the agent may have to supply one or more instructions to the system in order to reinitialize the interrupted print process, including the rename call. In some implementations, when the print job is allowed to proceed, there may be no indication to the user that any monitoring or interception occurred by the DLP agent. The system informs the user of the print job being successfully queued and printed. 
     If the agent determines that the print file includes sensitive data that should not be printed (“yes” from  408 ), then the print job may not be allowed to proceed. Instead of reinitializing the print job in the system, the agent may delete the intermediate print job file ( 412 ). In some implementations, the system may also generate and display an alert to one or more users indicating that the print job was prevented ( 414 ). 
     In addition to the immediate alert, the system may also record the print job prevention event ( 416 ). As noted above, this may involve collecting data from the intermediate print job file as well as any cache or control file included in the spool directory or otherwise accessible within the print system. In some implementations, the agent may take further steps if an event log shows multiple blocked printing jobs, such as informing a system administrator of the multiple attempts to print system information, or limiting system access for users with a history of blocked print jobs. 
     At this point it should be noted that techniques for print monitoring in accordance with the present disclosure as described above may involve the processing of input data and the generation of output data to some extent. This input data processing and output data generation may be implemented in hardware or software. For example, specific electronic components may be employed in DLP agents or similar or related circuitry for implementing the functions associated with print monitoring in accordance with the present disclosure as described above. Alternatively, one or more processors operating in accordance with instructions may implement the functions associated with print monitoring in accordance with the present disclosure as described above. If such is the case, it is within the scope of the present disclosure that such instructions may be stored on one or more non-transitory processor readable storage media (e.g., a magnetic disk or other storage medium), or transmitted to one or more processors via one or more signals embodied in one or more carrier waves. 
     The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Further, although the present disclosure has been described herein in the context of at least one particular implementation in at least one particular environment for at least one particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full breadth and spirit of the present disclosure as described herein.
Techniques for print monitoring are disclosed. In one embodiment, the techniques may be realized as a method including monitoring a spool directory associated with a printing system; identifying, for a print job file, a file management call that is made before the print job file is submitted to a printer driver to carry out a print job; blocking the file management call; analyzing the print job file for sensitive data; in response to determining that the print job file does not include sensitive data, re-initiating the file management call for the print job file; and submitting the print job file to a printer driver to carry out a print job.