skypeのブロックは困難

中国での中国電信によるversoを使ったskypeのブロックをテストしているが、実際skypeをブロックすることは困難なようだ。

To date all my common tricks for determining VOIP traffic on the Internet have been thwarted by the Skype designers. I have no idea if this result was a deliberate attempt to thwart detection or just an unintended side effect of their design. Perhaps a reader with inside knowledge will step forward and answer this and other questions. For now I have plenty on my plate, so I'll leave the mystery of Skype detection to my contemporaries.

Russell Shaw points to analysis by Art Reisman, CTO of APconnections, a company that specialized in packet shaping technology. Reisman could not detect and block Skype traffic, which is contrary to claims of a Chinese service provider which used Verso’s technology.

http://gigaom.com/2006/04/20/can-skype-be-blocked-maybe-maybe-not/