Armory
netcat 
(4 ratings)
Netcat is a featured networking utility which reads and writes data across network connections, using the TCP/IP protocol. It is designed to be a reliable "back-end" tool that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging ...
Snort (1 rating)
Snort is an open source network intrusion prevention and detection system utilizing a rule-driven language, which combines the benefits of signature, protocol and anomaly based inspection methods. With millions of downloads to date, Snort is the most widely deployed intrusion detection and prevention technology worldwide and has become the de ...
Metasploit Framework (3 ratings)
The Metasploit Framework is a development platform for creating security tools and exploits. The framework is used by network security professionals to perform penetration tests, system administrators to verify patch installations, product vendors to perform regression testing, and security researchers world-wide. The framework is written in the Ruby programming language ...
tcpdump (1 rating)
A command-line packet sniffer capable of dumping varying amounts of detail per packet to stdout, in real time. Originally written for UNIX-like systems, a port for Microsoft Windows was created and named WinDump.
John the Ripper (1 rating)
John the Ripper is a fast password cracker, currently available for many flavors of Unix (11 are officially supported, not counting different architectures), Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. Besides several crypt(3) password hash types most commonly found on various Unix flavors, ...
OpenSSH (1 rating)
OpenSSH is a FREE version of the SSH connectivity tools that technical users of the Internet rely on. Users of telnet, rlogin, and ftp may not realize that their password is transmitted across the Internet unencrypted, but it is. OpenSSH encrypts all traffic (including passwords) to effectively eliminate eavesdropping, connection ...
ShowIP (1 rating)
Firefox plugin by Jan Dittmer. Shows the IP address of the current page in the status bar. It also allows querying custom services by IP (right mouse button) and Hostname (left mouse button), like whois, netcraft. Additionally you can copy the IP address to the clipboard. This extension was formerly ...
Tamper Data (1 rating)
Firefox plugin by Adam Judson. Use Tamper Data to view and modify HTTP/HTTPS headers and post parameters, trace and time http response/requests, and security test web applications by modifying POST parameters.
aircrack (1 rating)
aircrack is an 802.11 WEP and WPA-PSK key cracking program that can recover keys once enough data packets have been captured. It implements the standard FMS attack along with some optimizations like KoreK attacks, thus making the attack much faster compared to other WEP cracking tools. In fact, aircrack is ...
wget (1 rating)
GNU Wget is a free software package for retrieving files using HTTP, HTTPS and FTP, the most widely-used Internet protocols. It is a non-interactive commandline tool, so it may easily be called from scripts, cron jobs, terminals without X-Windows support, etc. GNU Wget has many features to make retrieving large ...
Scapy (5 ratings)
Scapy is a powerful interactive packet manipulation program. It is able to forge or decode packets of a wide number of protocols, send them on the wire, capture them, match requests and replies, and much more. It can easily handle most classical tasks like scanning, tracerouting, probing, unit tests, attacks ...
BackTrack (5 ratings)
BackTrack is the most Top rated linux live distribution focused on penetration testing. With no installation whatsoever, the analysis platform is started directly from the CD-Rom and is fully accessible within minutes. It's evolved from the merge of the two wide spread distributions - Whax and Auditor Security Collection. By ...
RANCID (2 ratings)
RANCID monitors a router's (or more generally a device's) configuration, including software and hardware (cards, serial numbers, etc) and uses CVS or Subversion to maintain history of changes. Rancid currently supports Cisco routers, Juniper routers, Catalyst switches, Foundry switches, Redback NASs, ADC EZT3 muxes, MRTd (and thus likely IRRd), Alteon ...
Firebug (1 rating)
Firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
KeePass (4 ratings)
KeePass is a free open source password manager, which helps you to manage your passwords in a secure way.
Vistumbler (2 ratings)
A wireless network scanner for Windows Vista and Windows 7, which wraps Window's netsh utility to obtain wireless information. Also includes GPS support.
Observium (1 rating)
Observium is an auto-discovering PHP/MySQL based network monitoring system focused primarily on Cisco and Linux networks but includes support for a wide range of network hardware and operating systems. Observium has grown out of a lack of easy to use NMSes. It is intended to provide a more navigable interface ...
Ostinato (1 rating)
Ostinato is an open-source network packet and traffic generator and analyzer with a friendly GUI. It aims to be "Wireshark in Reverse" and become complementary to Wireshark. It features custom packet crafting with editing of any field for several protocols: Ethernet, 802.3, LLC SNAP, VLAN (with Q-in-Q), ARP, IPv4, IPv6, ...
mRemoteNG (1 rating)
mRemoteNG is a fork of mRemote, an open source, tabbed, multi-protocol, remote connections manager. mRemoteNG adds bug fixes and new features to mRemote. It allows you to view all of your remote connections in a simple yet powerful tabbed interface. mRemoteNG supports the following protocols: * RDP (Remote Desktop/Terminal Server) ...
Netdisco (1 rating)
Netdisco is an Open Source web-based network management tool first released publically in 2003. The target users are large corporate and university networks administrators. Data is collected into a Postgres database using SNMP and presented with a clean web interface using Mason. Configuration information and connection data for network devices ...
inSSIDer 
(7 ratings)
inSSIDer is an award-winning free Wi-Fi network scanner for Windows Vista and Windows XP. Because NetStumbler doesn't work well with Vista and 64-bit XP, we built an open-source Wi-Fi network scanner designed for the current generation of Windows operating systems. A year later, inSSIDer was discussed by Lifehacker and Tekzilla!
TrueCrypt (4 ratings)
TrueCrypt is a software system for establishing and maintaining an on-the-fly-encrypted volume (data storage device). On-the-fly encryption means that data are automatically encrypted or decrypted right before they are loaded or saved, without any user intervention. No data stored on an encrypted volume can be read (decrypted) without using the ...
Cacti (6 ratings)
Cacti is a complete network graphing solution designed to harness the power of RRDTool's data storage and graphing functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and user management features out of the box. All of this is wrapped in an intuitive, easy to use ...
Nagios (5 ratings)
Nagios is a host and service monitor designed to inform you of network problems before your clients, end-users or managers do. It has been designed to run under the Linux operating system, but works fine under most *NIX variants as well. The monitoring daemon runs intermittent checks on hosts and ...
Dynagen (2 ratings)
Dynagen is a front-end for use with the [Dynamips](/armory/dynamips/) Cisco router emulator. It uses an INI-like configuration file to provision Dynamips emulator networks. It takes care of specifying the right port adapters, generating and matching up those pesky NIO descriptors, specifying bridges, frame-relay, ATM switches, etc. It also provides a ...
GNS3 (6 ratings)
GNS3 is a graphical network simulator that allows you to design complex network topologies and to launch simulations on them. To allow complete simulations, GNS3 is strongly linked with [Dynamips](/armory/dynamips/), an IOS emulator which allows users to run IOS binary images from Cisco Systems, and [Dynagen](/armory/dynagen/), a text-based front-end for ...
Zabbix (2 ratings)
Zabbix is a network management system created by Alexei Vladishev. It is designed to monitor and track the status of various network services, servers, and other network hardware. It uses MySQL, PostgreSQL, SQLite or Oracle to store data. Its backend is written in C and the web frontend is written ...
Wireshark 
(17 ratings)
Wireshark is the world's foremost network protocol analyzer, and is the de facto (and often de jure) standard across many industries and educational institutions.
PuTTY (12 ratings)
PuTTY is a free implementation of Telnet and SSH for Win32 and Unix platforms, along with an xterm terminal emulator. It is written and maintained primarily by Simon Tatham.
nmap (3 ratings)
Nmap ("Network Mapper") is a free and open source utility for network exploration or security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Nmap uses raw IP packets in novel ways to ...