Comcast’s secret war on file sharing

Pub date December 5, 2007


TECHSPLOITATION For the past several months, Comcast has been covertly sending commands to your computer that tell it to stop receiving information — especially if that information is coming to you via BitTorrent, Gnutella, or other file-sharing applications. In May disgruntled Comcast users started posting on message boards about how BitTorrent and Gnutella weren’t working for them anymore. So researchers at the Electronic Frontier Foundation, along with an AP investigative journalist, started running tests on the Comcast network, using software tools to examine what exactly Comcast was doing to BitTorrent.

What they found was disturbing. Without telling customers, Comcast had begun a secret program to send automatic reset commands to customers’ computers if they were using BitTorrent, Gnutella, or a few other programs. None of these programs are illegal. Moreover, Comcast had sold its services to customers without informing them that this popular Internet software wouldn’t work on its network. And Comcast is still doing it.

To make matters worse, the method the folks at Comcast are using to shut down file sharing is underhanded. They stop BitTorrent by injecting reset data packets into information streaming between two computers on the Comcast network. Then Comcast makes the reset packets appear to be from one of the computers using BitTorrent — not Comcast. So even if customers know to look for these reset packets, they’ll believe the problem comes from the computer they’re trying to share files with.

When the EFF and angry customers confronted Comcast about its sneaky system, the company claimed that it was merely "slowing down" certain programs. But as the EFF pointed out last week in a research paper on the topic, reset packets are designed only to shut down communication between two computers. If Comcast wanted to slow down BitTorrent, it could have used a common program called a traffic shaper, which can adjust data speeds.

Comcast spokesperson Charlie Douglas told the Guardian that "Comcast is delaying peer-to-peer applications but not blocking them." He added that there is "no other technical way to delay" these applications than the method the company has chosen.

Without further explanation from Comcast, one is left wondering why the company would engage in such outrageously anticonsumer behavior. One possibility is that it views BitTorrent as a competitor. BitTorrent has made deals with various Hollywood studios to distribute movies online, which is something Comcast cable does for television. So maybe Comcast is playing dirty so its customers will turn to cable TV for movies instead of getting them online via BitTorrent.

For people who don’t care about using BitTorrent, though, Comcast’s behavior is still a gesture of bad faith. The company is demonstrating quite plainly that it won’t hesitate to deny basic Internet services to its customers without warning, and without even acknowledging that it’s doing it. Today those services are for file sharing. But tomorrow they could be for sending e-mail that doesn’t use Comcast’s Web mail system.

I also think Comcast’s actions are a harbinger of what’s to come as Internet service providers get sucked into larger media companies with cable or content-making divisions. No laws guarantee network neutrality online, so Comcast is free to engage in network prejudice. The company can block any service it wants, especially if there’s a financial incentive. Certainly, consumers can choose to go with another Internet service provider, and I hope they do. But in the future, market competition may not be enough.

If Comcast blocks BitTorrent, then another company might welcome BitTorrent traffic but block my favorite game services. Internet service will become like cable TV, where getting the full range of channels is incredibly expensive. Except it will be worse, because the Internet is a far richer and more diverse place than cable TV. Selectively blocking the Internet is like selectively blocking expression itself.

Annalee Newitz is a surly media nerd who gets her movies on BitTorrent.