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Beating Comcast's Sandvine On Linux With Iptables

HiroDeckard writes "Multiple sites reported a while ago that Comcast was using Sandvine to do TCP packet resets to throttle BitTorrent connections of their users. This practice may be a thing of the past as it's been found a simple rule in the Linux firewall, iptables, can simply just block their reset packets, returning your BitTorrent back to normal speeds and allowing you to once again connect to all your seeds and peer. If blocking the TCP packet resets becomes a common practice, on and off of Linux, it'll be interesting to see the next move in the cat-and-mouse game between customers and service providers, and who controls that bandwidth."

11 of 361 comments (clear)

  1. Tag: !news by Mr2001 · · Score: 5, Insightful

    This trick has been around for a while, hasn't it?

    The problem is, you can only filter out the RST packets on your end of the connection. But Sandvine also sends RSTs to the other end of the connection. That means it isn't enough for you to be running this iptables rule - all the peers you connect to have to be running it too.

    --
    Visual IRC: Fast. Powerful. Free.
    1. Re:Tag: !news by cryptoluddite · · Score: 5, Insightful

      The problem is, you can only filter out the RST packets on your end of the connection.

      That's only a temporary problem. The real problem -- for the ISPs -- is that the same software is running on each end of a p2p, so all of their efforts are guaranteed to fail eventually.

      For instance, p2p programs can start using UDP spread spectrum... pass packets on random ports. The receiver then basically implements a quick and dirty tcp-like connection over this (ie much worse for an ISP than actual TCP). Add encryption and random length so it's harder to filter out. Or there can be a shared random number seed for the shared ports. Just for example...

      There's probably some computer science or information theory law stating this, but they can't ultimately reduce the targeted traffic by more than the loss from encoding it as 'normal' traffic. For instance, if they limit torrents to 100k/s and the loss is 33% from 'base64' encoding the data as some kind of an html-ish doc then if normal web pages get more than 133k/s then torrents would be faster encoding them as 'normal' traffic.

      ... then they have to try to figure out what are real web pages/servers and what are really some other protocol pretending.

  2. You know what I hate? by deek · · Score: 5, Insightful

    It's when I see a comment on Slashdot, that seems to have no relation to the comment above it. Then I discover that the real parent post has been hidden by Slashdot's new comment system, and the child post linked to the grandparent.

    It's damn annoying! Slashdot, please, at least link the child to the "hidden comments" link. That way, I won't get head spins when someone appears to viscously lash out at an interesting post.

  3. Re:It's a trace buster buster buster by Tubal-Cain · · Score: 5, Insightful

    Straight-up blocking it is probably more clearly illegal than throttling.

  4. Re:They are doing it because they are crooks...... by Stormwatch · · Score: 5, Insightful

    But what they are really doing is trying to stop 2% of their customers from using 98% of the bandwidth, bandwidth they have to pay for. Remember, though they are selling "unlimited" internet access at some level *all* bandwidth is measured. Theirs is certainly measured by their upstream provider. There is really no "unlimited" bandwidth.

    Their own damn fault for selling something they don't have!

  5. A Fitness center analogy.. by AftanGustur · · Score: 5, Insightful
    Fitness centers operate similarly, they have numbers on how many times each member comes per week, and based on that (and other parameters) they price access to the center.

    Now, imagine you buy a year membership card.

    Then you start showing up each morning, and again in the evening.

    Then the fitness center comes to you and says: "You can come here, but we are going to lock all the doors when you show up, because you are using up to much resources and thus denying them to our other members.

    Do you think there would be any outrage ?

    --
    echo '[q]sa[ln0=aln80~Psnlbx]16isb572CCB9AE9DB03273snlbxq' |dc
    1. Re:A Fitness center analogy.. by Maxo-Texas · · Score: 5, Insightful

      Say that you found out a way to earn or safe a lot of money by staying on the fitness machines 16 hours a day.

      Suddenly, the 28 fitness machines they expected to service 5,000 people are being used from opening until closing by the same 28 people.

      Do you think the fitness companies and their customers would say "ah well... they've got us because of our advertising unlimited service."

      No- the next time your contract came up, it would have a clause that allowed them to force people to share the machines or something to protect them.

      You are being unreasonable. The cable companies are trying a weaselly scummy way to get out of the situation instead of just doing what they should do up front.

      1) Determine the real usage of their desired customer (say 20gb a month).
      2) Advertise 24gb a month for one "low rate" with a "reasonable $1 per gb"

      And eventually they will. Even if you have you current company in an iron clad contract, if it is losing money the situation *will* fix it self.

      ---

      The current isp situation in america is a complete joke and anti-capitalistic. We basically have duopolies in 99% of cities between AT&T and a cable company. That needs to stop and be broken up. The internet wires, like the roads, should put be put by the government.

      --
      She was like chocolate when she drank... semi-sweet at first and then increasingly bitter.
  6. Re:They are doing it because they are crooks...... by Crayon+Kid · · Score: 5, Insightful

    Their own damn fault for selling something they don't have!

    They always have. ISP's, especially those on the last mile, have historically sold 10 to 20 times the actual bandwidth to their customers. Except a while back the last mile was not a hot zone. There weren't so many things you can use huge amounts of bandwidth on.

    Today there are lots. Desktop apps move to the web, there's streaming, online gaming, all kinds of legal, semi-legal and illegal things to download, malware and the list goes on and on.

    The ISP's are caught in the middle of all this. They've entered this time period with pricing policies that belong in gentler times, and their infrastructure is also outdated and getting more so every day.

    On top of everything, everybody seems to think it's their job to carry the Internet on its back and figure it out somehow. The end customer likes to have huge amounts of bandwidth for pennies. The websites and online apps have bulk deals for bandwidth with providers that have efficient distribution infrastructures all over the world. And the last mile ISP is left to fight a dog eat dog fight with other similar local ISP or with a bigger area ISP, both of which will drive it out of business eventually.

    Not to mention the crazy politics involved, where they are required to act as copyright cops and other idiocies.

    So they're desperate. They're trying anything to "fix things". There are a couple of sane solutions but not without problems. The obvious move would be to rethink their pricing and start selling capped amounts of bandwidth. Filtering will always be passed somehow but a hard cap upstream is a hard cap. And nobody will be able to protest they're not getting what they're paying for.

    But this isn't easy either, because of the fierce competition. You do hard caps, you piss of customers. If they have a choice, they'll run to that new ISP that popped up in the neighborhood a week ago. Sure, that ISP will experience the same problems a while from now, but in the meantime you're short some income.

    Another solution is a world-wide effort to update infrastructure (better throughput, either hardware or software). But who's gonna pay for that? The last mile ISP's can't and won't and granted, it's not fair they should pay all of it. But the other interested parties like the status quo and won't pay either, but will bitch just as readily about filtering and caps and whatnot. In the end, the ISP's will probably turn to insightful investors like Google's dark fiber and become their prisoners and people won't like that either, but will conveniently forget they're the ones that pushed the ISP's into that corner.

    It's not just the ISP's fault, it's everybody's. The Internet has become an ecosystem, you gotta work together on all parts of it to see proper overall change.

    --
    i ate crayons when i was a kid and now i have two braincells and the blue ones taste nicer
  7. Re:They are doing it because they are crooks...... by grimwell · · Score: 5, Insightful

    But what they are really doing is trying to stop 2% of their customers from using 98% of the bandwidth, bandwidth they have to pay for. Remember, though they are selling "unlimited" internet access at some level *all* bandwidth is measured. Theirs is certainly measured by their upstream provider. There is really no "unlimited" bandwidth.

    Pisshaw. Large regional and national ISPs don't have "upstream" providers. They have a presence in a NAP(s) and peering agreements with other networks. The only costs they have is for the infrastructure; physical cables, equipment, power and people. They don't pay for bandwidth on a "meter". Their bandwidth is limited by equipment; available technology and costs.

    They are "managing bandwidth" to control last mile congestion. It is cheaper to mangle traffic than to upgrade the last mile. Plain and simple.

    --
    If the govt becomes a lawbreaker, it breeds contempt for law, it invites man to become his own law, it invites anarchy
  8. Re:They are doing it because they are crooks...... by CyberDog3K · · Score: 5, Insightful

    I might be less critical of them if they actually spent some of their abusively high rates on upgrading said failing infrastructure instead of god knows what.

  9. Re:They are doing it because they are crooks...... by PieceofLavalamp · · Score: 5, Insightful

    You've used "fierce competition" to describe the ISP market place. So i must assume you are being sarcastic. You really shouldn't bury sarcasm like that in between rather insightful points, you'll confuse people who aren't familiar with the issue... New ISPs haha funny.