How does dictionary password cracking work with Unix?
Dictionary password cracking is the most popular method for cracking Unix passwords. The cracking program will take a word list, and one at a time try to crack one or all of the passwords listed in the password file. Some password crackers will filter and/or mutate the words as they try them, such as substitute numbers for certain letters, add prefixes or suffixes, or switch case or order of letters. The most popular cracking utility is probably Alex Muffet’s program, Crack. Crack can be configured by an administrator to periodically run and automagically mail a nastygram to a user with a weak password, or run in manual mode. Crack can also be configured to run across multiple systems and to use user-defined rules for word manipulate/mutation to maximize dictionary effectiveness – very flexible. However it is probably too much program for the novice script kiddie. Another popular favorite is John the Ripper, based off of the popular DOS-based Jack the Ripper. Jack had a number of easy-
