Cox Caught Blocking BitTorrent

Remember that web-based tool to test whether your ISP is blocking BitTorrent that we linked to a couple weeks back? Thousands of broadband users around the world have tried it in the last couple of weeks. Well the results are in, and guess what? Comcast isn’t the only U.S. ISP with anti-P2P network management in place. Fellow cable provider Cox was also caught interrupting its subscribers’ BitTorrent uploads.

The Max Planck Institute for Software Systems, out of Germany, found that Cox interfered with roughly 50 percent of all measured transmissions. It also confirmed that Comcast is still actively blocking BitTorrent, despite numerous assurances to favor a protocol-neutral approach to network management. In fact, Comcast seems to be even stricter than Cox, disrupting roughly two-thirds of all uploads.

The Max Planck Institute is using a Java applet that simulates BitTorrent uploads to detect manipulations, such as the forged reset messages used by Comcast to end P2P transmissions. The applet doesn’t test for throttling, meaning ISPs that simply slow down transfers and prioritize other types of traffic aren’t detected, but the institute is working on proper ways to detect these types of interferences as well.

The current tests also found cases of BitTorrent blocking at seven other U.S. cable ISPs, but Max Planck researcher Krishna Gummadi told the AP that those results weren’t conclusive. His team didn’t find any signs of interference from DSL providers.

Regular NewTeevee readers shouldn’t be too surprised by these findings. We reported back in February that virtually all major U.S. cable ISPs have provisions in their Terms of Service that allow them to use Comcast-style BitTorrent blocking. Cox, for example, tells its subscribers that it might engage in “traffic prioritization and protocol filtering.” The cable company’s subscriber agreement also contains another red flag: “You expressly accept that such action on the part of Cox may affect the performance of the Service.”

The new findings include another interesting tidbit that could give Network Neutrality advocates new ammunition. Comcast has in the past defended its measures stating that it would only interfere with BitTorrent to minimize network congestion. That’s not true, according to the German researchers. They found instances of blocking around the clock and on every day of the week on the networks of both Comcast and Cox.

Free Press Policy Director Ben Scott used these findings to once again call for Net Neutrality legislation. “This research proves beyond a shadow of a doubt that consumers, Congress and the FCC must urgently pursue the complaints against network providers,” said Scott. “Consumers have no reason left to trust their cable company.”