Comcast really does block BitTorrent traffic after all

Comcast for months has denied blocking BitTorrent traffic, but new tests show that it takes aggressive filtering steps that AT&T, Time Warner Cable, and Cablevision do not.

Declan McCullagh Former Senior Writer
Declan McCullagh is the chief political correspondent for CNET. You can e-mail him or follow him on Twitter as declanm. Declan previously was a reporter for Time and the Washington bureau chief for Wired and wrote the Taking Liberties section and Other People's Money column for CBS News' Web site.
Declan McCullagh
2 min read

For a few months Comcast has been the subject of scattered reports that say it throttles BitTorrent traffic.

TorrentFreak saidin August that Comcast was surreptitiously interfering with file transfers by posing as one party and then, essentially, hanging up the phone. But when we contacted Comcast at the time, it flatly denied doing it.

Thanks to testsreported Friday by the Associated Press, however, it's clear that Comcast is actively interfering with peer-to-peer networks even if relatively small files are being transferred.

The testsinvolved transferring a copy of the King James Bible through the BitTorrent network on Time Warner Cable, Cablevison, AT&T and two Comcast connections (in Philadelphia, Boston and San Francisco). Only the Comcast-connected computers were affected.

This is significant. The Gutenberg versionof the King James Bible is only 4.24MB, which is relatively tiny and indicates that Comcast was singling out even small files.

Now, even though there's been some musing that Comcast can't do this, I'd be surprised if a court would say that it was somehow unlawful. Comcast's Terms of Service says: "You further agree to comply with all Comcast network, bandwidth, and data storage and usage limitations. You shall ensure that your bandwidth consumption using the Service does not exceed the limitations that are now in effect or may be established in the future. If your use of the Service results in the consumption of bandwidth in excess of the applicable limitations, that is a violation of this Policy...if the Service is used in a way that Comcast or its suppliers, in their sole discretion, believe violate this AUP, Comcast or its suppliers may take any responsive actions they deem appropriate.

Which is pretty broad.

The danger for Comcast is twofold. First, its hyperactive filtering may zap perfectly legitimate file transfers, which seems to have happened in one case involving a customer using Lotus Notes.

Second, it encourages countermeasuressuch as obfuscating BitTorrent traffic or encrypting it. That means that future efforts by Comcast to manage its traffic may be far more difficult. (If Comcast had merely slowed down BitTorrent transfers instead of cutting them off completely, users wouldn't be escalating this arms race as quickly.)

Probably the best result would be tiered pricing. BitTorrent users who are heavy users of bandwidth would pay more, while average home users would pay less. It's not perfect, and lots of Internet users may not like a tiered pricing model, but it's probably better than escalating a technological arms race, or not being able to use BitTorrent at all.