The Electronic Frontier Foundation noticed the same sort of packet forging that the AP did (and that Broadband Reports readers did some time ago), and continued its testing to see if other applications are affected. The answer is a disturbing “yes.” The results of additional testing done by the EFF indicate Comcast is sending forged reset packets with some Gnutella traffic. When the EFF ran a Gnutella node on a Comcast connection, the forged reset packets disrupted communication between the nodes.
What’s particularly insidious about Comcast’s packet forging is that it’s transparent to both its customers and those on the opposite ends of the connection. Applications such as BitTorrent and Gnutella retain some of their functionality, but they’ll also appear to malfunction for no apparent reason.
Even if you accept the argument that all P2P traffic is inherently evil, and that Comcast has the right to disrupt it in order to put a stop to copyright infringement, Comcast’s traffic-shaping efforts have apparently extended beyond the realm of P2P and into good old enterprise groupware. Kevin Kanarski, who works as a Lotus Notes messaging engineer, noticed some strange behavior with Lotus Notes when hooked up to a Comcast connection last month.
When Lotus Notes users attempt to send e-mail with larger attachments over Comcast’s network, Notes will drop its connection. Instead of a successfully sent e-mail, they’re greeted with the error message, “Remote system no longer responding.” Kanarski did some digging and has managed to verify that Comcast’s reset packets are the culprit. Instead of passing the legitimate e-mail through its network, Comcast’s traffic monitoring tool (likely Sandvine) is sitting in the middle, imitating both ends of the connection, and sending reset packets to both client and server.