AntiCrack [IA][Direct] -
Checks vulnerability of UNIX passwords in the same manner as Crack does, but it's faster because it checks "raw (not encrypted)" passwords.
Index - Irish Computer Security Archives [IA][Direct] -
Includes bug listings and fixes, Security Mailists, Security Newsgroups, security system tools, hacker groups mags, hacking tools & more
MLD's Unix Security Page [IA][Direct] -
Unix & TCP/IP Network Security Page. Focused on system penetration and system designs which lead to security failures. Software available online.