EFF proves Comcast is screwing with BitTorrent, releases instructions for testing your own ISP

A pair of new Electronic Frontier Foundation reports prove that Comcast is degrading and interfering with BitTorrent, and shows how you can use free software to test your own ISP to see if it is doing the same:
In addition to providing evidence of network interference, the EFF study also explains how Comcast's selective degradation of BitTorrent traffic undermines future Internet innovation. "The Internet has enabled a cascade of innovations precisely because any programmer--whether employed by a huge corporation, a startup, or tinkering at home for fun--has been able to create new protocols and applications that operate over TCP/IP, without having to obtain permission from anyone," the EFF wrote. "Comcast's recent moves threaten to create a situation in which innovators may need to obtain permission and assistance from an ISP in order to guarantee that their protocols will operate correctly. By arbitrarily using RST packets in a manner at odds with TCP/IP standards, Comcast threatens to Balkanize the open standards that are the foundation of the Internet."

The EFF also published a second report (PDF), which provides detailed technical instructions explaining how to use Wireshark to reproduce their study and test for ISP packet injection.


See also:
How the AP busted Comcast for blocking BitTorrent
Why Comcast's BitTorrent-fux0r is bad for quality of service
Comcast also screwing with Gnutella and Lotus Notes (!?!)
Comcast actively blocks P2P traffic
Modest proposal for Comcast's net-filtering


  1. The Wireshark instructions are a good start, but a bit hard to use. Even a technologist would need some time to set it up. Could one of you open-source wizards create an easy-to-use tool for this.

  2. I’m pretty sure my ISP (Shaw cable in Canada) screws with Bittorrent too… it takes ages to download anything, and I have to reload the program when it slows to a tiny trickle.

    I suspect there are more ISPs than we know who control their Bittorrent traffic.

  3. Traffic shaping across consumer Internet service networks is absolutely happening, and for very good reason. The principal reason this is necessary is that most peer-to-peer applications will seek to fill all available capacity, essentially disregard network congestion, taking a fire-and-forget approach to sending data. It can overwhelm network infrastructure very easily.

    Consumer Internet service is NOT a tier one, committed information rate service. You can not expect to have your peak data rate available to you individually at all times. It falls to your network provider to determine which traffic gets priority, and which traffic does not, when there is contention for network resources. Since peer-to-peer traffic verges on abusive of network resources, disregarding inherent contention and congestion controls, it tends to be at the top of the list of traffic that gets dropped.

    All this fuss about spoofed packets is much ado about nothing. When an excessive number of flows is being generated by a particular application on a particular host, sending a TCP reset to flows that are not going to receive service is the most elegant way of terminating those flows. Face it, your 3000 BitTorrent connections are not always going to be served by your ISP, and resetting the ones that aren’t going to get served is simply being blunt about it, and frankly, it is doing you a favour.

    This whole tide of outrage about Comcast or Insert-ISP-Name-Here throttling peer-to-peer traffic is going to end in exactly one place. ISPs are going to have to spell out that if you want all of your traffic passed to and from your host at a certain data rate with no QoS or policing, you can pay full commercial rate for committed data rate services. Expect to pay $150/Mbps for that per month at the very least. If you want your $30, $40, $50 home Internet service your traffic is going to be shaped, full stop.

    This is NOT a net neutrality issue, this is a network management, and ISP marketing issue. The EFF needs to give their head a shake, and people need to lose their sense of entitlement to run abusive network applications across a consumer broadband service.

  4. I agree with Greyhame above – most people want broadband over dial-up, and 8Mb/s over 2Mb/s etc. because of the responsiveness.

    The typical household wants pages that load quickly for the time that they use their web-browser / email, rather than to potentially transfer 8Mb/s of data 24/7, 365 days a year, which is what BitTorrent could attempt to do.

    The solution I’d prefer to see is a service that degrades based on total bandwidth transferred – serve up the first 1Gb a day at full rate, then progressively throttles back to something that the network could sustain 24/7, in order to prevent people who leave BitTorrent running from causing congestion.

    That keeps the neutrality aspect – only total bandwidth is counted – and protects the system against overload.

    The other thing that’s needed is to make it explicitly clear what is and is not permitted in the contract that comes with the Broadband service. Most firms sell “unlimited” bandwidth packages, even though that can’t really be the case.

  5. “Utorrent uses encryption so you wont get throttled no mater who your provider is.”

    Are you sure? I definitely noticed that uploads stopped a few months ago. Now the downloads are disabled for the most part. I can see plenty of seeders.

  6. I am a shaw user in Canada also. They seem to be shaping traffic by interrupting my internet connection for 5 seconds whenever my bandwidth usage is high (over 1Mps). The affect of this is that I lose any connections to anyone I am sharing data with and have to reestablish that connection. It slows file transfers to a crawl if they continue at all.

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