Linux - Penetration Testing, Digital Forensics, and Hacking Distributions

CAINE (Computer Aided INvestigative Environment)

http://www.caine-live.net 

BlackBox

http://www.backbox.org

DEFT  (Digital Evidence & Forensic Toolkit)

http://www.deftlinux.net/download

KALI
 
http://www.kali.org/downloads

Matriux
 
http://www.matriux.com

HELIX

http://www.e-fense.com 

Hakin9
 
http://www.hakin9.org

Network Security Toolkit (NST)

http://www.networksecuritytoolkit.org