In the middle of summer 2007, I was contacted by my big boss at TorrentFreak, Ernesto van de Sar, to investigate a report he’d had. According to some reports on forums like DSLreports, Comcast users were having issues keeping or making BitTorrent connections, especially seeding, and could I take a look at it?
So I did.
I reached out to my friends, and friends-of-friends, looking for Comcast customers (and non-Comcast customers), and started some research going. I was nearly a hermit for 2 weeks, as I talked people through setting up the data collection systems, and then processed the data. It did, however, pay off as it led to proof that there was indeed something screwy going on with Comcast connections. Not all connections, mind, but most, and spread all over the US, from Utah to New England.
Basically, Comcast was using a product from Sandvine to disrupt the use of BitTorrent. When it detects BitTorrent seeding, it would perform a man-in-the-middle attack, and send RST packets to both ends of the connection, terminating the connection, made to look like it came from the other end. Imagine a phone call, and the phone company decides to terminate it but makes it seem like the other side deliberately hung up on you. Continue reading…