John the Ripper is a fast password cracker, currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. It supports several crypt(3) password hash types commonly found on Unix systems, as well as Windows LM hashes. On top of this, many other hash types are added with contributed patches, and some are added in John the Ripper Pro. This is the community enhanced version.
Source: John The Ripper 1.7.7 Jumbo 6