single: Single crack mode. This is only recommended for weak passwords as it includes only a few rules and a small wordlist.
Usage: john -single crackme.txt
wordfile: Uses a wordlist (basically a dictionary attack). What this does is tries every word in the list until it finds a match or you reach the end of the list. This is quicker than the default (bruteforce) attack, but I don't recommend this because it doesn't always find a match. More notes on wordlists below.
Usage: john -wordfile:password.lst crackme.txt
rules: Lets you define the rules for using wordlists. I don't use wordlists, so if you want to use this option I wont help you. Ok, ok, I'm just lazy. Shoot me.
incremental: I like this method. It allows you to do a bruteforce attack under certain modes.
Usage: john -incremental:alpha crackme.txt (only letters) john -incremental:digits crackme.txt (only numbers) john -incremental:lanman crackme.txt (letters, numbers, and some special characters) john -incremental:all crackme.txt (all characters)
-- Edited by so9or on Thursday 31st of March 2011 10:20:24 AM