Skype

Skype is a proprietary and closed source software for telephonie over Internet, written by the Kazaa-people. Skype operates on a peer-to-peer model and routes calls through NATs and firewalls. Because of its easy use and a lot of features, it became very popular and has about 9 million users worldwide.


 * official webseite: http://www.skype.com/

Security

 * Article 4.1 of the Skype End User License Agreement allows computers running Skype to be used to route third party traffic. The algorithm which Skype uses to select these so-called "supernodes" appears to take account of bandwidth availability.


 * Philippe BIONDI and Fabrice DESCLAUX presented at the Black Hat Europe Conference 2006 a talk "Silver Needle in the Skype" about the security of Skype: "No way to know if there is/will be a backdoor" (pdf)


 * It looks like the Windows Skype client reads out your Bios data: http://www.pagetable.com/?p=27


 * ausführliche Diskussion auf deutsch http://www.univie.ac.at/comment/06-2/062_27.html

Alternatives
Try a open source alternative: openwengo