Comcast Impersonates Users' Computers To Meddle With Internet Traffic

Comcast uses its own computers to masquerade as those of its users in order to disrupt and throttle internet traffic—specifically the peer-to-peer kind—whenever it chooses, according to nationwide independent tests carried out by the Associated Press. A Comcast rep dances around the charge by saying that the company doesn’t “block” access to anything—but he makes no mention of throttling or disrupting connections to shape traffic, probably because if he did, he’d have to admit to it or blatantly lie.

There aren’t many FCC regulations against traffic shaping—“the act of throttling a given piece of Internet traffic based on its type, like BitTorrent or VOIP”—but Comcast’s selective targeting and disruption of P2P services is the strongest evidence of a company intentionally degrading service by “actively impersonating” its customers’ computers.

Comcast’s technology kicks in, though not consistently, when one BitTorrent user attempts to share a complete file with another user.

Each PC gets a message invisible to the user that looks like it comes from the other computer, telling it to stop communicating. But neither message originated from the other computer — it comes from Comcast. If it were a telephone conversation, it would be like the operator breaking into the conversation, telling each talker in the voice of the other: “Sorry, I have to hang up. Good bye.”

The president of BitTorrent tells DailyTech that some Canadian companies also block and/or degrade P2P traffic, but Comcast is the first U.S. company to engage in it this aggressively. Both articles point out that it affects the entire file-sharing network, including companies who use P2P for legitimate business services like Blizzard Entertainment, which distributes World of Warcraft updates via BitTorrent.

“Comcast blocks some Internet traffic” [MSNBC]
“Comcast Screws with File-Sharing Traffic” [DailyTech]
(Photo: Getty)


Edit Your Comment

  1. LionelEHutz says:

    Real net neutrality laws with teeth are the only solution to this nonsense.

  2. Lordy, people do illegal stuff on the Internet with regular downloads. Is Comcast going to start throttling all of their traffic?

  3. Geekybiker says:

    Do we really want our ISP deciding what should be fast/slow or even available when we’re supposedly paying for open access?

  4. tedyc03 says:

    Somebody needs to sue Comcast for violating people’s rights or something.

  5. fredmertz says:

    I have much less of a problem with them throttling some traffic than I do with them not being upfront about it. Heavy bittorrenters can put a pretty big strain on bandwidth. They should just let their customers clearly know what their rules are.

  6. mantari says:

    Impersonating the participants in an active communications session, in order to close that session, is blocking access. And that’s exactly what an RST packet does.

    They’re just playing with words. “No, no. We’re not blocking anyone’s access. We’re just closing connections! They are free to open them up again! We’re not stopping them!”

  7. axiomatic says:

    I had to get my latest World of Warcraft patch via manual download because of Comcast crappy Sandvine “shaping” junk. Just kept restarting the download, no progress ever. While my manual download came to me at 8Mb. Fishy.

    Unfortunately for me, Comcast is the ONLY option for my house as my DSL C.O. is 10,000 ft + from my house so DSL is out. (Tried it already too, 1mb down was the best I could get and that is not fast enough for my needs.)

  8. Jaysyn was banned for: says:

    Can you say bye bye Common Carrier Status?

    Who wants to be the first porn-in-the-Biblebelt related lawsuit to take advantage of this?

  9. Buran says:

    @mantari: except… you’re not, since they’ll just impersonate you again and close it again.

  10. urban_ninjya says:

    If you think about it.. Business usually pay of bandwidth on a per/gigabyte plan instead of a monthly plan..

    With users from the casual web browser, to bandwidth hogs such as gamers and ppl who download movies and music.

    There probably need some sort of better pricing model, whether it is a 2 or 3 tier model where you have casual usage that is throttled and a full unrestricted model where they have what is fully available 24/7. Of some sort of pay per amount of data sent back and forth.

  11. @fredmertz:

    There is no strain on bandwidth, or at least there shouldn’t be a strain if comcrap isnt over selling their areas.

    The bottom line is comcrap is intercepting data they shouldn’t be allowed access to. It’s no business of theirs what I’m doing.

  12. LatherRinseRepeat says:

    Although traffic shaping and throttling sucks, it’s their network and they can pretty much do whatever they want. However, they really should be upfront and clearly state this before customers sign up for service. And they should also state that “unlimited” access isn’t really unlimited.


    Cable internet is not considered a common carrier.

  13. howie_in_az says:

    Let me get this straight… Comcast sells you an internet connection. You use said internet connection. Comcast then says “no you’re using it wrong” and doesn’t let you use it the way you want to.

    Isn’t the next step in this something like “customer leaves company that doesn’t let them use their internet connection the way they want to use it” ?

  14. Xkeeper says:

    “Not blocking acccess”…

    There’s a website I occasionally visit(ed). I can ping the server it’s one just fine. Everybody else can access it great. But no connecting on port 80 there!

    The site I visit even knows about it, and it’s a problem only Comcast users suffer from. Hm!

  15. Xkeeper says:

    @howie_in_az: Makes sense, unless you have no other option. A lot of people forget there’s either one cable provider or one DSL provider, and sometimes both. You don’t exactly have choices.

  16. JeffMc says:

    Does anyone else hope the juror who accused the lady in the big RIAA case of lying about it being possible to spoof an IP is following this? Here we have an ISP spoofing traffic from one computer to another.

    Maybe Comcast was the one sharing those MP3s! :)

  17. MPHinPgh says:

    @urban_ninjya: If you think about it.. Business usually pay of bandwidth on a per/gigabyte plan instead of a monthly plan..

    This is untrue. Businesses typically pay for a guaranteed bitrate (1.5 Mbps or such). I have not seen the first company that pays for a maximum nunber of bytes in a set time period (and after that you either have to pay more money or you get no more bytes).

    Granted, there is no SLA on residential class service, but even still, Comcast has no right to randomly block traffic. If the network can’t handle the load, drop the committed rate or something, but like one of the other posters said, be upfront about it…

  18. mac-phisto says:

    methinks home depot is going to have a run on hammers this weekend…

  19. JustAGuy2 says:


    Of course they’re overselling their areas. If they weren’t, your service cost would be much higher. Want 6Mbps of committed bandwidth without oversubscription? Get 4 T-1s. That’s about $1600/month.

  20. Raziya says:

    FFS, maybe that’s why my WoW patches download so slow and I have to get them from another site…thanks, Comcast! …you assholes!

  21. whydidnt says:

    This is one of the reasons I always ignore Comcast’s “great” Triple-Play offer. I don’t even use Bit-torrent, but if they are picking on Bit-Torrent today, it will probably be NetFlix, or some other service/download I like to use, tomorrow. Fortunately, I have the option of using fast (5 Mbps) DSL in my area, so it’s not a huge problem for me.

    The bottom line is if Comcast wants to “protect their network and provide a high level of service to all of their customers” than they need to market their service as limited use. We hear how the first 10 MB of a file are at a lightning fast 12 MB/second, then we should also hear that if you are uploading a large file, then they block it. I doubt many people would complain if they had a $29.00/month service that was limited in this or other manners from time to time, but had the option to get pay for a $89 or $99 service that did not impose those same limitations.

    That’s true consumer choice and would be the norm if our stupid government hadn’t gone off the deep end with locally granted monopolies on wire to our houses in years past.

  22. Bay State Darren says:

    @mac-phisto: Hilarious! It’s a good thing they’re having a big clearance sale.

  23. spevman says:

    Okay, so does anyone actully have some useful info on if there is any way (software solution, bittorrent client settings/plugins) to circumvent Concast’s efforts to traffic shape? Is there any way to encrypt/mask the data so it can’t be identified as bittorrent traffic?

  24. Corydon says:

    My reading of the article is that Comcast doesn’t prevent downloads using BitTorrent, but only prevents the uploads (please correct me if I’m wrong).

    Now my understanding is that most ISPs have a clause in their Terms of Service that forbid you to run a server. Isn’t that what you’re doing if you’re making a file available for download from your home computer?

    So if you’re violating the Terms of Service, what’s the problem with Comcast’s response? I suppose it would be better if they came right out and said “You’re violating the TOS; cease and desist or we’ll cut off your service,” instead of obfuscating and denying.

    Am I way off base here? Can any computer geeks speak to the point?

  25. weave says:

    @spevman: []

    Linux to the rescue! :)

  26. And who was the idiot who said we don’t need Net Nuetrality?

  27. gnubian says:

    In regards to tiering, I already have the upper tier Comcast service .. couldn’t tell you if my torrents are getting whacked, I’m usually into huge swarms .. I maintain a sustained 50kbits up ..

    You should be encrypting everything .. read this .. []

    Having linux doesn’tmake a difference .. they aren’t throttling based on OS ..

    What’s more disturbing is this .. []

    It isn’t just torrents .. torrents might just be the noticed tip of the iceberg ..

  28. meehawl says:

    “Comcast is the first U.S. company to engage in it this aggressively.”

    No, RCN started injecting interrupt packets into BT sessions three years ago, preventing seeding of 100% torrents. Apparently, though, Comcast is far more hated than RCN, and larger, so *now* finally everyone notices.