Computer security "agents" must master the same tools used by the hackers they seek, and many of these programs are available to download for free. The man-in-the middle attack, (also known as the monkey-in-the middle) is a useful method of scanning network data and extracting what is known as interesting data, (passwords, e-mail, data files). Listed below you will find 10 programs used to assault and defend networks around the world.

1. Ethereal is the most widely used network protocol analy...