Last week, the Associated Press published evidence that U.S. cable operator Comcast is deliberately disrupting the file-sharing service BitTorrent; shortly thereafter, the Electronic Frontier Foundation published a report that the cable operator seems to also be deliberately disrupting the file-sharing service Gnutella, and possibly also interfering with message exchanges with the corporate messaging system Lotus Notes if they involved large file attachments.
The EFF reports that attempts to operate a Gnutella peer-to-peer sharing node on a machine connected to the Internet via Comcast produced inconsistent results ownin to the reception of forged reset packets which, essentially, tell the sending and receiving computer to stop talking to each other. These reset packets aren’t being sent by the computers on either end of the connection, however; instead, they are apparently being forged within Comcast’s network and directed to the machines, each with forged address information.
The shutdown technique is virtually identical to that cited by the Associated Press in its investigation of BitTorrent sharing on machines using Comcast Internet service. These so-called “man in the middle” attacked involving forged packets are typical of network attacks; however, in this case, they appear to be generated by the ISP itself in a deliberate effort to either block or manage certain types of network traffic.
The EFF also noted a report from Kevin Kanarski that Comcast is apparently using a similar technique to disrupt messages sent via Lotus Notes which bear large file attachments.
Although peer-to-peer service BitTorrent is best-known as a haven for illegal distribution of copyrighted video, music, and software, the company also transfers fully licensed video and music, and can (and is) used to transfer perfectly legitimate content. Similarly, peer-to-peer transfer technologies power services like Skype and Joost. Some of these services could compete directly with Comcast’s cable television and on-demand video offerings.
Comcast has not commented on the nature of any filtering techniques it may employ on its network, or whether it used forged packets to regulate traffic and services.
