Here is a list of the 10 best LiveCD distributions dealing with security. These distros can be run entirely off the CD without any install on the machine. They are great for penetration testing and offer portability. Best of all you get to choose which flavor you need at any given point just by switching a cd.
Some of them are:
BackTrack is the result of the merging of two Innovative Penetration Testing live Linux distributions Whax and Auditor.
check it out here.
Operator is a very fully featured LiveCD totally oriented around network security (with open source tools of course). Check it out here.
Mainly based around Penetration Testing, PHLAK is a must have for any pro hacker/pen-tester. Check it out here or at the mirror here.
The Auditor security collection is a Live-System based on KNOPPIX. With no installation whatsoever, the analysis platform is started directly from the CD-Rom and is fully accessible within minutes. Chec kit out here.
5. L.A.S Linux
Local Area Security Linux is a ‘Live CD’ distribution with a strong emphasis on security tools and small footprint. Check it out here.
STD is a Linux-based Security Tool. Actually, it is a collection of hundreds if not thousands of open source security tools. Check it out here.
Helix is more on the forensics and incident response side. Helix is a customized distribution of the Knoppix Live Linux CD. Check it out here.
FIRE is a portable bootable cdrom based distribution with the goal of providing an immediate environment to perform forensic analysis, incident response, data recovery, virus scanning and vulnerability assessment. check it out here.
The main goal of nUbuntu is to create a distribution which is derived from the Ubuntu distribution. Check it out here.
10. INSERT Rescue Security Toolkit
INSERT is a complete, bootable linux system. It comes with a graphical user interface running the fluxbox window manager while still being sufficiently small to fit on a credit card-sized CD-ROM. Check it out here.