Select a tool from "Top 100 Network Security Tools". The use of an open-source tool is highly encouraged.
Cain and Abel
UNIX users often smugly assert that the best free security tools support their platform first, and Windows ports are often an afterthought. They are usually right, but Cain & Abel is a glaring exception. This Windows-only password recovery tool handles an enormous variety of tasks. It can recover passwords by sniffing the network, cracking encrypted passwords using dictionary, brute-force and cryptanalysis attacks, recording VoIP conversations, decoding scrambled passwords, revealing password boxes, uncovering cached passwords and analyzing routing protocols. It is also well documented. For downloads and more information, visit the Cain and Abel homepage.
2) It is required that you install and run the tool in an enclosed network environment or use it on your own computer ONLY. An enclosed network environment means a non-operational networked system without any physical connection to other working computing environments (e.g., the Internet). Special attention should be paid when you use network scanners, sniffers, hacking tools or password crackers because their usage may violate an organization's security policies or compromise other computing resources.............