John The Ripper

John The Ripper (JtR) is a password cracking program.

Basic Usage

Dumb Brute Force

To brute force a password and to have John iterate through all the possible sequences:

john --incremental --stdout

This defaults to the incremental mode parameters. You can specify a different mode, say to use only integers:

john --incremental=digits --stdout

Bruting with an External Program

You can pipe the brute force attack to an external program if for some reason you can't get John to do what you want (or can't figure it out like me).

# john --incremental=pstoken --stdout

TODO: How do you resume?

Further Reading

• http://www.openwall.com/john/doc/RULES.shtml
• http://www.openwall.com/john/doc/EXAMPLES.shtml
• http://linuxconfig.org/password-cracking-with-john-the-ripper-on-linux
• http://contest-2010.korelogic.com/rules.html
• http://backreference.org/2009/10/26/password-recovery-with-john-the-ripper/