I just had an “interesting” experience. While travelling I was alerted that my main office PC was sending out enormous amounts of traffic. According to the tech person involved, the culprit was … Skype. As bizarre as it might seem, the contention seems to be that my PC became a sort of Skype super-supernode, one that was routing all Skype traffic for, you know, the world, and that was causing unfortunate issues, like saturating a centi-megabyte pipe.
Was it really Skype? I don’t know yet, as we’ve disconnected the PC and some diagnostics are going to be done. It would certainly be puzzling, because if Skype was so poorly architected as to network-misbehave like this then you would think that all sorts of people would be reporting the same problem. Similarly, while it’s possible that there’s some trojan mimicking Skype traffic on the PC, that too would be unusual — I practise “safe computing”, and I’ve not heard of any such ‘bot.
Thoughts? Ideas? I certainly got me researching Skype trojans, supernode takeovers, maps of SuperNodes, and reading about others with fears of a Skype planet and their ideas for blocking this fast-morphing, port-randomized, encrypted, virus-like app.
[Update] From a Computerworld article (“Skype supernodes sap bandwidth”) last October:
Testing by Computerworld showed that Skype starts up a large number of TCP and UDP connections when it starts up, but the supernode issue didn’t occur. However, reports elsewhere warn against using Skype on connections with high bandwidth and IP addresses routeable on the internet. In supernode mode, Skype is reputedly able to saturate 100Mbit/s connections. Universities with high-speed connections often ban Skype usage because of this. [Emphasis mine]