Open Source

Accesstream
Open-source identity and access management software provides authentication, authorization, reporting and audit functions. Can be embedded in existing applications or installed standalone.
http://accesstream.com

dradis
Open-source software for sharing information during penetration testing.
http://dradis.nomejortu.com/

The Freefire Project
Provides information about open source security software.
http://sites.inka.de/lina/freefire-l/index.en.html

FreeNAC
LAN access control tool providing VLAN assignment and management, access control, live network inventory and documentation of patch cabling.
http://www.freenac.net

Libssh project
Libssh is a free C library implementing the SSH protocol in conjunction with libcrypto from OpenSSL.
http://0xbadc0de.be

NetworkTools
A Java based toolkit made up of a protocol analyzer and a port scanner to monitor and troubleshoot security and network problems.
http://networktools.sourceforge.net

Winpooch
Free watchdog for Windows, it monitors modifications in directories and in the registry so as to detect spywares and trojans when they are installed.
http://winpooch.free.fr/