This article will show how to use Hydra to check for weak passwords. Hydra tries all possible password combination against a server on the Internet until one valid one is found to log in to the server. It is a powerful tool for hackers and network administrators alike.
You can download it from the following link: https://packetstormsecurity.com/files/download/105503/thc_hydra_article_r3.pdf
Source: https://packetstormsecurity.com/files/105503/Password-Authentication-Cracking.html