john

Featureful Unix password cracker

John the Ripper is a fast password cracker, currently available for many flavors of Unix (eleven are officially supported, not counting different architectures), DOS, Win32, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. Besides several crypt(3) password hash types most commonly found on various Unix flavors, supported out of the box are Kerberos AFS and Windows NT/2000/XP/2003 LM hashes, plus several more with contributed patches (over 40 of additional hash and cipher types).