Nmap

Nmap ("Network Mapper") is a free and open-source network scanner created by Gordon Lyon (also known by his pseudonym "Fyodor Vaskovich"). Nmap is used to discover hosts and services on a computer network by sending packets and analyzing the responses.
Nmap provides a number of features for probing computer networks, including host discovery and service and operating system detection. These features are extensible by scripts that provide more advanced service detection, vulnerability detection, and other features. Nmap can adapt to network conditions including latency and congestion during a scan.
Nmap started as a Linux utility and was ported to other systems including Windows, macOS, and BSD. It is most popular on Linux, followed by Windows.
Features.
Nmap features include:
Nmap can provide further information on targets, including reverse DNS names, device types, and MAC addresses.
Typical uses of Nmap:
User interfaces.
NmapFE, originally written by Kanchan, was Nmap's official GUI for Nmap versions 2.2 to 4.22. For Nmap 4.50 (originally in the 4.22SOC development series) NmapFE was replaced with Zenmap, a new official graphical user interface based on UMIT, developed by Adriano Monteiro Marques.
Web-based interfaces exists that allow either controlling Nmap or analysing Nmap results from a web browser, such as IVRE.
Output.
Nmap provides four possible output formats. All but the interactive output is saved to a file. Nmap output can be manipulated by text processing software, enabling the user to create customized reports.
History.
Nmap was first published in September 1997, as an article in Phrack Magazine with source-code included. With help and contributions of the computer security community, development continued. Enhancements included operating system fingerprinting, service fingerprinting, code rewrites (C to C++), additional scan types, protocol support (e.g. IPv6, SCTP), and new programs that complement Nmap's core features.
Major releases include:
Legal issues.
Nmap is a tool that can be used to discover services running on Internet connected systems. Like any tool, it could potentially be used for black hat hacking, as a precursor to attempts to gain unauthorized access to computer systems; however, Nmap is also used by security and systems administrators to assess their own networks for vulnerabilities (i.e. white hat hacking).
System administrators can use Nmap to search for unauthorized servers, or for computers that do not conform to security standards.
In some jurisdictions, unauthorized port scanning is illegal.
License.
Nmap was originally distributed under the GNU Public License (GPL). In later releases, Nmap's authors added clarifications and specific interpretations to the license where they felt the GPL was unclear or lacking. For instance, Nmap 3.50 specifically revoked the license of SCO Group to distribute Nmap software because of their views on the SCO-Linux controversies.
In popular culture.
In "The Matrix Reloaded", Trinity is seen using Nmap to access a power plant's computer system, allowing Neo to "physically" break into a building. The appearance of Nmap in the film was widely discussed on Internet forums and hailed as an unusually realistic example of hacking.
Nmap and NmapFE were used in "The Listening", a 2006 movie about a former NSA officer who defects and mounts a clandestine counter-listening station high in the Italian alps.
Nmap source code can be seen in the movie "Battle Royale", as well as brief views of the command line version of Nmap executing in "Live Free or Die Hard" and "Bourne Ultimatum". In 2013, Nmap continued to make appearances in movies including popular sci-fi movie "Elysium".
The film "Dredd", a film adaptation of the famous Judge Dredd comics, was released in 2012 and also contains multiple Nmap scenes. Nmap is used for network reconnaissance and exploitation of the slum tower network. It is even seen briefly in the movie's trailer.
The command Nmap is widely used in the video game "Hacknet", allowing to probe the network ports of a target system to hack it.
In "Snowden", Nmap is used in the aptitude test scene about 14 minutes into the movie.
In academia.
Nmap is an integral part of academic activities. It has been used for research involving the TCP/IP protocol suite and networking in general. Besides being a research tool, Nmap has also become a research topic.
Examples.
$ nmap -A scanme.nmap.org
Starting Nmap 6.47 ( https://nmap.org ) at 2014-12-29 20:02 CET
Nmap scan report for scanme.nmap.org (74.207.244.221)
Host is up (0.16s latency).
Not shown: 997 filtered ports
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 5.3p1 Debian 3ubuntu7.1 (Ubuntu Linux; protocol 2.0)
80/tcp open http Apache httpd 2.2.14 ((Ubuntu))
9929/tcp open nping-echo Nping echo
Warning: OSScan results may be unreliable because we could not find at least 1 open and 1 closed port
Device type: general purpose|phone|storage-misc|WAP
Running (JUST GUESSING): Linux 2.6.X|3.X|2.4.X (94%), Netgear RAIDiator 4.X (86%)
OS CPE: cpe:/o:linux:linux_kernel:2.6.38 cpe:/o:linux:linux_kernel:3 cpe:/o:netgear:raidiator:4 cpe:/o:linux:linux_kernel:2.4
Aggressive OS guesses: Linux 2.6.38 (94%), Linux 3.0 (92%), Linux 2.6.32 - 3.0 (91%), Linux 2.6.18 (91%), Linux 2.6.39 (90%), Linux 2.6.32 - 2.6.39 (90%), Linux 2.6.38 - 3.0 (90%), Linux 2.6.38 - 2.6.39 (89%), Linux 2.6.35 (88%), Linux 2.6.37 (88%)
No exact OS matches for host (test conditions non-ideal).
Network Distance: 13 hops
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel
TRACEROUTE (using port 80/tcp)
HOP RTT ADDRESS
1 14.21 ms 151.217.192.1
2 5.27 ms ae10-0.mx240-iphh.shitty.network (94.45.224.129)
3 13.16 ms hmb-s2-rou-1102.DE.eurorings.net (134.222.120.121)
4 6.83 ms blnb-s1-rou-1041.DE.eurorings.net (134.222.229.78)
5 8.30 ms blnb-s3-rou-1041.DE.eurorings.net (134.222.229.82)
6 9.42 ms as6939.bcix.de (193.178.185.34)
7 24.56 ms 10ge10-6.core1.ams1.he.net (184.105.213.229)
8 30.60 ms 100ge9-1.core1.lon2.he.net (72.52.92.213)
9 93.54 ms 100ge1-1.core1.nyc4.he.net (72.52.92.166)
10 181.14 ms 10ge9-6.core1.sjc2.he.net (184.105.213.173)
11 169.54 ms 10ge3-2.core3.fmt2.he.net (184.105.222.13)
12 164.58 ms router4-fmt.linode.com (64.71.132.138)
13 164.32 ms scanme.nmap.org (74.207.244.221)
OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 28.98 seconds