back to article Comcast cops to BitTorrent busting

Eight months after an independent researcher revealed that Comcast was secretly throttling BitTorrent and other P2P traffic, the beleaguered American ISP has at last admitted that's exactly what it's doing. Of course, Comcast thinks this throttling is one great idea. And the company continues to deny it did this for months …


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  1. Steve Evans

    Very curious...

    Given that the simplest method of looking after a network is to just throttle traffic, it's odd that they go out of their way to get/make a system that injects fake tcp packets to knock out the customers application.

  2. Mark

    As I said to begin with

    If the problem is BT requests produce a storm when it starts, resetting the connection is the LAST thing you want to do. Because what will you do then? Start it up again.


    And have they copped to impersionation and fraudulent misrepresentation, seeing as they were pretending to be customers outside their network?

  3. Chad H.


    even when their trying to tell the truth they lie... Can companies be diagnosed with mental health problems? cos this one could be diagnosed as a pathological liar.

  4. Anonymous Coward
    Anonymous Coward

    Yep. Exactly as I suspected

    The title should be: Comcast does not know Cable specs, has no idea of how to manage IP and QoS, but tries to manage network through silver bullets and vendor voodoo. This is a popular diseases in large cablecos and telcos.

    It manages uplinks only. For uplinks on a CMTS interface you can specify a proportion where the user stations try a collision-detect/retry Ethernet style and a slice to each station which tells it when and how it is allowed to transmit. All it takes is to make use of the spec. From there on a station that transmits too much can be easily throttled and other users allowed to transmit instead.

    Further to this, the traffic in question traverses the CMTS. It is trivial on the CMTS to hierarchically queue traffic for different users. You specify a minimal bandwidth for each user and "abusers" are pushed back to make space for other users demand as necessary. Granted this works well only for TCP, but most P2P traffic is indeed that - TCP.

    If the CMTS vendor has not implemented either of these methods, making it implement them costs nothing. For Comcast it is just a part of their normal vendor relationship. No need to buy special kit and do special rocket-science style P2P busting.

    So the subtitle should be "Comcast has officially declared itself clueless".

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  6. Nexox Enigma


    @Steve Evans:

    Throttling traffic is actually a non-trivial task, especially when you can't do it based on ports, and even more especially when you've got to do it on ISP-scale traffic. Killing a tcp connection every time it starts up means you just have to deal with it once, as opposed to once per packet. I imagine that a single regexp could take care of it. Plus they obviously don't value the BT service (or their customers,) so they don't see a problem with terminating uploads instead of adding some delay.


    BT actually produces a storm all the time. It is probably a bit more hectic when a client is trying to connect out to the swarm when it first loads a torrent, but killing a single upload connection at a time isn't going to re-trigger any storms. Most clients will retry upload connections once they're killed, and I imagine that some will just give up on peers that never connect.

    I really kinda hope some sort of precedent gets set (Comcast getting clobbered for spoofing packets on a wide scale, preferably) which keeps ISPs docile for at least a couple more years.

    The upside is that they probably wouldn't start throttling any decent protocols( judging by their statement in the article,) so (if I was a poor Comcast customer) I would probably see better bandwidth on my downloads.

  7. Kamilion Schnook of Second Life

    I'm a comcast user...

    I live in California, I use comcast, and I bittorrent linux ISOs constantly (damn ubuntu's Hardy alphas).

    As a network admin, I don't mind that they're throttling the bandwidth, as I do the same with Thibor on my WRT54G.

    What DOES bother me is that Comcast is throttling traffic and not TELLING ANYONE how, why, or when they're doing this. The silence and lies are what pisses me off about this.

    Oh well, one more reason to turn torrent protocol encryption on. I don't have anything to hide, but I prefer to manage my own bandwidth, thankyaverymuch.

  8. Anonymous Coward
    Paris Hilton

    Network Socialism

    and the trees are all kept equal by hachet, axe and saw.

  9. Paul

    My heart bleeds...

    Poor musicians; "slaving" away all day making music and expecting to get rich out of it... then blaming someone else when you don't... years ago people used to blame A&R or radio for ignoring them... now they blame "pirates"... NOTHING has really changed....

    Artists are, on the whole, not rich people. If you enjoy what you do and make a little money then great... if one day you are recognised as a special talent, even better - but if you're not satisfied with your income then why not get a proper job like the rest of us?

    The world has plenty of musicians; if you're not prepared to put in a little time and passion for the love, rather than for your wallet, perhaps you're in the wrong job?

  10. Morely Dotes

    Anyone want to give odds...

    ...on which new version of a BT client will have a checkbox: "ignore RST packets?"

  11. Nick Palmer
    Thumb Down

    @Network Socialism

    Odd title when the situation has arisen because unregulated market economics allowed Comcast to swallow or freeze out competitors meaning that they now have an effective monopoly position in many areas, which they can and obviously do.

  12. RW

    @ Chad H

    Corporations are run by people who simply don't understand that you are supposed to tell the truth as a matter of course. The funny thing is that telling the truth is a lot simpler, in both the short- and long run, than lying and trying to cover your ass.

    So-called executives, bean counters, spin doctors, and lawyers: they're all guilty of violating social norms. The excuse is "maximizing shareholder value"; I hope Milton Friedman is being fried in molten sulfur in hell for inventing *that* one.

    Time to radically overhaul the parameters under which corporations operate to make it clear that their first duty is to society as a whole.

  13. P. Lee

    Where are comcast running resets?

    Warning: Uninformed opinion ahead!

    Comcast *could* be doing this at their network egress points. ADSL connections are naturally throttled by lower upload speeds than cable connections. That makes the comcast network disproportionately attractive to *non-comcast* torrent users. That is, people who don't pay comcast anything at all. This is only *upload* traffic remember - unless they are running a commercial p2p server, comcast customers are hardly being deprived of anything. If you are a commercial user, you'd suspect you would be breaking the comcast T's&C's and can't really complain.

    Having said that, the whole affair has been badly managed. Comcast should have come clean about what was going on. Maybe they could provide an certificate-signed open-source azeurus/ktorrent plugin which throttles upload bandwidth at critical times (perhaps just for non-comcast IP addresses) and registers with a comcast server that it is doing so. Comcast could then provide a discount on their monthly fees based on the traffic volume throttled. I'm sure it could be abused, but for uploads, where's the incentive to do so? It only has to mostly work to have the required effect.

  14. Anonymous Coward

    @Andrew Crystall

    >> i.e. Anything stupid enough to obey RFC's and obey reset packets

    You mean the Windows TCP stack? Cause BitTorrent isn't responsible for obeying those particular packets. God help us all if they go as far as to write their own hacked TCP drivers and write directly to the NIC at layer 2. God only knows what kind of chaos that would cause.

    @Comcast: WTF? I understand the need to manage traffic, but to lie about it? Someone should go to jail for fraud on that one. Of course that will never happen, as they will claim operational ignorance.

  15. Jeff Dickey

    @Brent Gardner

    Of course they're operationally ignorant. Name one corporate monopoly that actually *satisfies* its victims (no, then they'd be 'customers') as a matter of course, and doesn't spend millions of its victims' payment dollars on The Best Congress Money Can Buy. If they need to buy more Congresscritters, they just up the subscription rates - it's not like they have to worry about competitors. Sort of like Congress... though I'm not quite clear on who learned that trick from whom. But the point is, Comacast et al are spending money and time (money again) on this sort of BS when they could be at least marginaly keeping up with what residential customers in the Free World consider marginally acceptable Net access (like the 10 Mbps down/2 up that is mid-range in Singapore, or the 1 Gbps being rolled out in Korea. Think about that for a minute, and then go back to your 1.5 Mbps 'high-speed' connection.)

    If there was ever a poster child for striking down the whole concept of corporate personhood (see for a discussion) and the century-plus of Really Bad Law based on it, Comcast and the other megacomms would be on the *very* short list.

  16. Nexox Enigma

    @P. Lee

    """This is only *upload* traffic remember - unless they are running a commercial p2p server, comcast customers are hardly being deprived of anything."""

    You'll want to look into the BT protocol. Clients that get data from you will preferentially give data back to you. No ability to upload will make it harder to download. Plus any decent BT tracker will require that you keep up a decent download/upload ratio, which would be impossible.

    Moreover, they disturb the entire mechanism by which BT operates. It assumes that any download will upload in order for the system to work.

    Comcast needs to remember that the Internet was made for porn... and thats about all BT is useful for these days.

  17. Richard Bennett

    Odd remark.

    "So there you have it. Comcast throttles your BitTorrent uploads only when you're most interested uploading them."

    No, they only throttle your uploads after your download has finished, when you're least interested in them. It's not very complicated, Cade.

  18. James Henstridge


    One problem with the "impersonation" argument against Comcast's behaviour is that many ISPs impersonates services to some extent.

    A common one is to redirect port 80 requests to their proxy server so they can cache pages, reducing use of their internet links and providing better service to their users.

    Another is redirecting SMTP connections to their server, so they can monitor the traffic (and potentially cut off spammers). This one is a bit more controversial, and is a pain if you are trying to access a corporate SMTP server while on the road.

    Now I realise that these two examples are quite different to inserting TCP reset packets into an overwise untouched stream, but it makes arguments like "the ISP should never interfere with customer TCP connections" a bit less clear cut.

  19. Anonymous Coward

    @Impersonation, and the technical difficulties argument.

    The telephone company has the right to manage traffic on their network too, but if they tried to do it by getting you to use your phone less, by calling you up with the spoofed caller ID of a friend and faking a message in their voice telling you never to call them again, you wouldn't think it anything less than completely clear cut.

    The examples you gave /don't/ muddy the waters all that much. Transparent http proxies don't alter the content. If they /do/ alter the content (such as Rogers have been doing lately), it is seriously controversial, as recent events have shown.

    So the degree of acceptance toward ISPs' impersonation practices that currently occur is _predicated_ on them not *interfering* with your use of the service nor *falsifying* the data through abuse of their position, which is essentially that of a man-in-the-middle. Conveying our packets is a very serious social and moral responsibility, like conveying our postal mail or phone calls, and tampering with either should be equally taboo.

    Re. the technical difficulties argument: I'm not buying that one either, or only marginally convinced that it couldn't be addressed pretty straightforwardly using existing technologies and only a modicum of development and deployment effort. If you can spot a p2p syn+ack packet flying across the network and send a rst, you can just as easily slap a tag on the traffic and shunt the punter sideways onto a lower traffic priority vlan, or I would like to know why not?

  20. SImon Hobson Bronze badge

    It seems to me that ...

    ... the "problem" is trying to control traffic before it gets to their first upstream box capable of 'normal' queuing/throttling. Ie, unlike ADSL where the uplink is a non-shared resource until it gets through the mux at the exchange, here we have a shared medium with multiple users fighting over it.

    In this case, it does seem like the only, but very drastic, measure available is to terminate the session(s) that take up too much of the shared medium.

    From comments I've read, and I have no direct knowledge of this, it does sound like modern cable kit DOES support some form of traffic control where it is needed, so the question really should be "why doesn't this ISP use it ?" I suspect the answer is porbably something along the lines of "We don't want to spend any money on it !" which seems to be the response of UK ISPs to criticism that their networks are over congested and need upgrades !

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