Tracking cyberspies
Tracking Cyberspies Through the Web Wilderness
http://www.nytimes.com/2009/05/12/science/12cyber.html?_r=2&partner=rss&emc=rss
Many of the spying operations are government sponsored and they too have certain drawbacks. The open source software used is Wireshark.
Can be downloaded at http://www.wireshark.org .