KeePass is a free open source password manager, which helps you to manage your passwords in a secure way. You can put all your passwords in one database, which is locked with one master key or a key file. So you only have to remember one single master password or select the key file to unlock the whole database. The databases are encrypted using the best and most secure encryption algorithms currently known (AES and Twofish).
No Script is a firefox add on that blocks active content from running in the browser.
Nipper (short for Network Infrastructure Parser, previously known as CiscoParse) audits the security of network devices such as switches, routers, and firewalls. It works by parsing and analyzing device configuration file which the Nipper user must supply.
ClamAV is an open source (GPL) antivirus engine designed for detecting Trojans, viruses, malware and other malicious threats. It is the de facto standard for mail gateway scanning. It provides a high performance mutli-threaded scanning daemon, command line utilities for on demand file scanning, and an intelligent tool for automatic signature updates. The core ClamAV library provides numerous file format detection mechanisms, file unpacking support, archive support, and multiple signature languages for detecting threats.
Splunk is a tool to search, report, monitor and analyze real-time streaming and historical IT data. It collects logs from a variety of sources and makes them searchable in a unified interface.
fgdump is a newer version of the pwdump tool for extracting NTLM and LanMan password hashes from Windows. It is also capable of displaying password histories if they are available. It outputs the data in L0phtCrack-compatible form, and can write to an output file. fgdump attempts to disable antivirus software before running. It then runs pwdump, cachedump (cached credentials dump), and pstgdump (protected storage dump).
The OpenSSL Project is a collaborative effort to develop a robust, commercial-grade, full-featured, and Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library. The project is managed by a worldwide community of volunteers that use the Internet to communicate, plan, and develop the OpenSSL toolkit and its related documentation.
OSSIM is the de facto standard Open Source SIEM. The goal of AlienVault's OSSIM is to provide a comprehensive compilation of tools that work together to provide a detailed view over each and every aspect of your networks, hosts, physical access devices, server, etc.
PGP is the famous encryption system originally written by Phil Zimmerman which helps secure your data from eavesdroppers and other risks. GnuPG is a very well-regarded open source implementation of the PGP standard (the actual executable is named gpg). While the excellent GnuPG is always free, PGP is now owned by Symantec and costs a lot of money
OpenVAS is a framework of several services and tools offering a comprehensive and powerful vulnerability scanning and vulnerability management solution. It is a forked version of nessus. It can be a stand alone package, or an operating system.