Comcast Throttles BitTorrent Traffic, Seeding Impossible
Written by Ernesto on August 17, 2007Over the past weeks more and more Comcast users started to notice that their BitTorrent transfers were cut off. Most users report a significant decrease in download speeds, and even worse, they are unable to seed their downloads. A nightmare for people who want to keep up a positive ratio at private trackers and for the speed of BitTorrent transfers in general.
ISPs have been throttling BitTorrent traffic for almost two years now. Most ISPs simply limit the available bandwidth for BitTorrent traffic, but Comcast takes it one step further, and prevents their customers from seeding. And Comcast is not alone in this, Canadian ISPs Cogeco and Rogers use similar methods on a smaller scale.
Unfortunately, these more aggressive throttling methods can’t be circumvented by simply enabling encryption in your BitTorrent client. It is reported that Comcast is using an application from Sandvine to throttle BitTorrent traffic. Sandvine breaks every (seed) connection with new peers after a few seconds if it’s not a Comcast user. This makes it virtually impossible to seed a file, especially in small swarms without any Comcast users. Some users report that they can still connect to a few peers, but most of the Comcast customers see a significant drop in their upload speed.
The throttling works like this: A few seconds after you connect to someone in the swarm the Sandvine application sends a peer reset message (RST flag) and the upload immediately stops. Most vulnerable are users in a relatively small swarm where you only have a couple of peers you can upload the file to. Only seeding seems to be prevented, most users are able to upload to others while the download is still going, but once the download is finished, the upload speed drops to 0. Some users also report a significant drop in their download speeds, but this seems to be less widespread. Worse on private trackers, likely that this is because of the smaller swarm size
Although BitTorrent protocol encryption seems to work against most forms of traffic shaping, it doesn’t help in this specific case. Setting up a secure connection through VPN or over SSH seems to be the only solution. More info about how to setup BitTorrent over SSH can be found here.
Last year we had a discussion whether traffic shaping is good or bad, and ISPs made it pretty clear that they do not like P2P applications like BitTorrent. One of the ISPs that joined our discussions said: “The fact is, P2P is (from my point of view) a plague - a cancer, that will consume all the bandwidth that I can provide. It’s an insatiable appetite.”, and another one stated: “P2P applications can cripple a network, they’re like leaches. Just because you pay 49.99 for a 1.5-3.0mbps connection doesn’t mean your entitled to use whatever protocols you wish on your ISP’s network without them provisioning it to make the network experience good for all users involved.”
Customers on the other hand like to fully use their connection, and don’t agree that traffic shaping is the correct solution. One reader commented: “If you pay for an internet connection, that’s what you should get from your ISP — an internet connection. Not a connection that will let you browse the web and check email, but little else. If an ISP has issues with the amount of data a customer is transferring, then the ISP needs to address that issue with that customer, and not restrict every user in one class of traffic.”
I guess this battle will go on for a while and I would advise Comcast users to try setting up a VPN connection to get around the traffic shaping, other users who find out that they are throttles might try BitTorrent encryption first, that seems to work quite well in most cases.
More details about the Sandvine application can be found here.
Previously: BitTorrent Anime Downloaders Identified, $3500 Bill in the Mail
Next: TorrentPod Episode 43
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Chris H.
Encryption. Doesn’t. Work.
Oh, and if you call, CSRs are either kept in the dark or lying through their teeth. They’ll tell you they don’t know what you’re talking about.
just change your DNS
Mwahahaha
Extremaly easy
From the description of Sandvine, it enforces torrent parasites … downloads via BitTorrent are OK, but if the downloader decides to give back to the community for that file, they get shut down. Only Comcast recipients from that user’s up-torrent are OK.
I’m with Comcast (Atlanta area). Cannot seed anything. The party is over. Considering that there is generally only one choice in a given ares for cable and cable internet, changing ISP’s is not an option for me. Seems my torrenting days are over.
[quote comment="148281"]I am as of today the 17th of August a Comcast cable internet subscriber. I’m not sure if this is affecting all Comcast or possibly untrue, but I am currently downloading/seeding without any issues. I seed on timer where day,early evening hours i upload at 32kb/s and late evening early morning at 64 kb/s and have done so for almost 2 years on a 24/7 basis with no problems from Comcast for doing so. I’ve up’d over 500 Terabytes this year so far, and that’s just in bitorrent traffic. I still use my net connection for games and surfing/email as well on top of this. I live in a smaller area so this may be the reason we aren’t affected. I can’t say anything bad about Comcast as of this time period. I had issues with sprint/earthlink dsl and their crap speeds before this but comcast has been reliable and almost always higher than rated speeds.[/quote]
Thats now true. 500 terabytes is impossible in less then 250 years with the speed you are quoting.
First of all, stop using the phrase “ISPs reserve the right to traffic shape”.
ISPs do not have a RIGHT to control diddly squat for any packet leaving MY line. I provide them with money in the agreement that they provide me with a delivery method and routing for my packets, nothing more.
I do not believe that my ISP performs traffic shaping on our business connection, but if I ever suspected they did, I would respond aggressively, rightly asserting that it is a heinous breach of my privacy and personal security for them (My ISP) to read any higher than Level 3 in the OSI Model, as well as the privacy and security of anyone using my connection.
I understand that many of you live in the United States and as such, will live out the rest of your existences without knowing true freedom. For this I am sorry, and I believe there is no hope for any of you receiving the service that you are paying for because none of you are willing to pick up the phone and call your ISP and ask questions and demand answers.
Just imagine if everyone who came across this posting clued in and demanded that ISPs stop breaching your privacy by reading above the Layer 3 layer. If the consensus in the technical community was such that to traffic shape was a heinous breach of privacy, trust, and personal security, then ISPs would be barred from doing so by law.
Some people know these laws as Net Neutrality.
It’s amazing what apathy will get you these days. Loss of respect from your peers, diminished sense of self, and even George W Bush for President two terms in a row.
Just a Canadians 0.2c/CA
Uh, the Valve platform STEAM uses BitTorrent protocol for its content downloading part. I’ve gotten a lot of people talking to me about how they can’t download/extremely low download rates for STEAM. Isn’t Comcast breaking some sort of law if they are stopping people from downloading the games they spent money to buy?
[quote comment="148765"]Uh, the Valve platform STEAM uses BitTorrent protocol for its content downloading part. I’ve gotten a lot of people talking to me about how they can’t download/extremely low download rates for STEAM. Isn’t Comcast breaking some sort of law if they are stopping people from downloading the games they spent money to buy?[/quote]
Correction, Comcast users can’t download/extremely low download rates.
I’m on a mac, but my router is connected to a windows machine. can someone please explain how to use either ipfw or iptables? i’m desperate! I can’t upload for more than 10 seconds until comcast bumps my P2P connection, and my ratio has been sufferbing because of it. Thanks for the help you guys.
[quote comment="148737"]Just encrypt the data transfer within the Bit Torrent client. It causes the CPU to spike a little more, but the ISP cannot track what is going in and out of your comp…[/quote]
Does NOT work.
Comcast is evil- it is that simple. I would have canceled my service a long time ago had Comcast been my ISP. I understand some people have no other options for high speed internet access. In my view dialup surpasses high speed when an ISP beging putting restricitons on the line. These are severe restrictions. People need to contact Comcast and complain and then cancel the service. If I were up to it I’d start a class action lawsuit for deceptive practices.
I am using Comcast of Beaverton, Oregon.
I’m using Azureus with full RC4 (no fall backs and crypto port extension set) and I’m routing all my tracker communications through The Onion Router. I’m not seeing any major slowdowns in leaching/seeding popular .torrents (1000+ peers).
There has been a recent mysterious inability to connect to peers as of late. Usually when I first start up a .torrent. But, it clears up after the first 10 minutes or so. Then I get full throttle.
OFF TOPIC: It’s also important for all of you in the U.S. to visit all .torrent related index sites (isohunt.com, for example) with The Onion Router for your anonymity. I say this because of recent court decisions to require some web sites - like TorrentSpy - to disclose their connection logs to the MPAA/RIAA gang. And also make sure you are using Safepeer and/or Peer Guardian 2. Take care =)
-Balkin
St. Helens, OR
Try this to seed: With Bitcomet (sorry utorrent doesn’t have all the features needed) recheck a finished file but stop it at 99.9%. Then set the file to seed only so it never downloads the last .1%.
[quote comment="148330"]does anyone know the ipfw equivalent for the iptables command:
iptables -A INPUT -p tcp –dport $TORRENT_CLIENT_PORT –tcp-flags RST RST -j DROP
i’m running osx, and i’d like to give it a shot.[/quote]
ipfw add deny tcp from any to any 54367 in tcpflags rst
Replace 54367 with whatever port you are using for your bittorrent client.
I used to have an ISP called Adelphia but then Comcast bought them out almost a year ago. Ever since then service has been horrible and my internet speed is down.
I am with Comcast and haven’t really noticed a difference yet. This will suck, because alot of the material I share with Bittorent isn’t copyrighten, its alot of family videos I share of my daughter. My cousins do the same, its pretty much the best way to share a few months worth of video to stay in touch. If Comcast starts to hit my connection, I will leave them.
[quote comment="148757"][quote comment="148281"] I am currently downloading/seeding without any issues. I seed on timer where day,early evening hours i upload at 32kb/s and late evening early morning at 64 kb/s and have done so for almost 2 years on a 24/7 basis with no problems from Comcast for doing so. I’ve up’d over 500 Terabytes this year so far, and that’s just in bitorrent traffic. I still use my net connection for games and surfing/email as well on top of this.
Thats now true. 500 terabytes is impossible in less then 250 years with the speed you are quoting.[/quote]
Sorry my bad. I must have had a brain fart while typing this. I meant 500 gig’s. But then maybe you too should reread what you type before criticizing next time.
[quote comment="148807"][quote comment="148330"]does anyone know the ipfw equivalent for the iptables command:
iptables -A INPUT -p tcp –dport $TORRENT_CLIENT_PORT –tcp-flags RST RST -j DROP
i’m running osx, and i’d like to give it a shot.[/quote]
ipfw add deny tcp from any to any 54367 in tcpflags rst
Replace 54367 with whatever port you are using for your bittorrent client.[/quote]
So I used the command in terminal “sudo ipfw add deny tcp from any to any 54367 in tcpflags rst” (with my port number). what is this gonna do, and can i change this back if need be? i don’t even know what i just did and if it’s working yet. it seems to be doing something… i’m seeing green smiley faces for the first time in months in azureus…
[quote comment="148694"]… Cox has been nothing but great since we got broadband five years ago.[/quote]
I have Cox too, and it’s great here (I’m in the DC area): fast upload and they’ve never complained to me about using it. And I love them more for every story I read about a different ISP doing something lame like this…
The reason Comcast gets away with this shit is they have no competition; Comcast users can’t switch ISPs unless they move.
I’m lucky enough to live in an area with both Cox cable and Verizon FiOS. Cox service, which was already pretty good, got even better when FiOS came into town (I remember my upload cap tripling one day). Competition is good, folks.
If you want the facts instead of hype or speculation, read Sandvine’s whitepaper…
http://www.sandvine.com/general/getfile.asp?FILEID=16
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