The tabs above list tools and some tutorials for their use. All of the tools presented are open source and free for download. Visit Sectools for a more comprehensive list.
For a full functionality penetration testing, security-enhanced operating system, try Backtrack 4. BackTrack contains many of the utilities you might be looking for. It includes utilities for packet sniffing, network mapping, privilege escalation, digital forensics, vulnerability scanning, etc. Among the utilities included are: Wireshark, Ettercap, Metasploit, Kismet, Nmap, Hydra, and RFMON.