John the Ripper is a UNIX password cracker, currently available for UNIX (tested with Linux x86, FreeBSD x86, Solaris 2.x SPARC, OSF/1 Alpha), DOS, WinNT/Win95. John the Ripper supports the following cracking modes: - wordlist with or without rules; - "single crack", makes use of the login/GECOS information; - incremental, tries all character combinations; - external, allows you to define your own cracking mode. - MD5 based password files support WWW: http://www.openwall.com/john/