BackTrack – Linux security distribution

Matriux – Debian based security distron

Ubuntu –Samurai – Web Testing Framework

OWASP Live CD project – Web application security distro

Pentoo – Security-focused livecd based on Gentoo

Katana – Portable multi-boot security suite

KON-BOOT – Change contents of a linux/windows kernel while booting

Linux from scratch! – Building your own custom Linux system

SUMO Linux –Pentesting packages for ubuntu – A script to configure Ubuntu box for pentesting

BackBox Linux – Flexible penetration testing distribution