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
440 Responses (Add yours or TrackBack)
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I’m using Comcast with Azureus. I have noticed no problems with seeding. It works just fine
I’ve read the white paper. Reading between the lines, it looks like they’re intercepting the communications with the tracker. Anyone affected should tunnel tracker communications over Tor and see if it helps.
Thanks for the white paper. It’s amazing to me that these guys thought we wouldn’t notice our seeding being screwed with so dramatically. It looks like Sandvine sold this to Comcast as being a painless way to limit bandwidth. All of you who are similarly afflicted should contact them and threaten to walk. At the prices they charge, I’m sure they make money off of even heavy P2P users. Max upload speeds aren’t that fast to begin with. Now that this has been on Slashdot, maybe they will get enough complaints to make a difference. Please do your part.
BTW, it looks like popular torrents seed better because you pick up new peers as fast as the old ones are dropped. It doesn’t max out my upload bandwidth, but it sure helps.
[quote comment="148763"]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.[/quote]
Wow - you ARE a moron, aren’t you?
Read your agreement with them, and see just what you agreed to let them do to you.
Sorry, the tube of vaseline isn’t included.
– RF
I’m not surprised that Comcast is doing this. They have a pretty long history of not giving you what you payed for. Thankfully, Speakeasy DSL has been a fantastic alternative. I can saturate my upstream bandwidth for weeks on end and not hear a word from them. It costs about $100 for a 3.0 down 768 up connection, but you get exactly what you pay for.
Jesus. About five people out of all you posters actually have a clue. How utterly pathetic the rest of you are.
Go ahead and keep living in your little dream world where it costs “peanuts” for an ISP to add more WAN bandwidth, or to split a fiber node, or to deploy another RT. All it takes is a *small handful* of abusive users to be able to consume all the available bandwidth on ANY network. That includes LAN’s, broadband, you name it! Bandwidth is a commodity, not an endless resource.
Another thing that no one here knows or seems to be capable of understanding is the incredible load that thousands of simultaneous connections from each P2P user can place on an ISP’s routers and switches. This shit is expensive, and having to replace it once a year instead of once every five years does not make providers happy.
I know you all think that your ISP is somehow on a mission to defraud you of your money, and that they don’t want you to download pirated movies and whatnot. The truth of it is, at least from my experience, ISP’s don’t give a shit what you’re doing as long as it doesn’t impact other users on the network. They can’t be held responsible for you torrenting Sopranos, so stop thinking that they’re out to get you. The same exact thing applies to ISP’s that forbid users from running their own servers.
PLEASE, do a little research before you continue pissing and moaning about how unfair your ISP’s practices are!
FUCK!
- Tate
Twice in the past 24 hours my Verizon FIOS connection has gone dead. Checked System alerts and no sign of any internal event.
What in heavens name do they think people are using high speed connections FOR?
Verizon keeps trying to sell me their TV service but I get all of the TV shows I want to watch via BT.
Sometimes I wonder if they really have ever thought this whole high speed thing through.
so my room mate downloads/seeds and this is why i keep getting disconnected while playing WoW?
Wow, after reading this article and responses, I really am happy to live on another side of Atlantic ocean, where the bandwidth is cheap and there is no such thing as a “traffic limit”.
Guys, move to Europe :)
Can any of you give me some pointers on where to enter this using DD-WRT on a Linksys router?
iptables -A INPUT -p tcp –dport $MY_BITTORRENT_PORT –tcp-flags rst rst -j DROP
Do I do it via SSH or through the web interface Administration->Commands?
> Can any of you give me some
> pointers on where to enter this
> using DD-WRT on a Linksys router?
Do not bother. It does not work unless both sides of all (or at least most) of your peer connections also block RST-flagged packets.
[quote comment="148283"]
Funny. Then don’t oversell the lines.
[/quote]
That’s how the “lines” are run, and will continue to be run.
[quote comment="148970"]Jesus. About five people out of all you posters actually have a clue. How utterly pathetic the rest of you are.
Go ahead and keep living in your little dream world where it costs “peanuts” for an ISP to add more WAN bandwidth, or to split a fiber node, or to deploy another RT. All it takes is a *small handful* of abusive users to be able to consume all the available bandwidth on ANY network. That includes LAN’s, broadband, you name it! Bandwidth is a commodity, not an endless resource.
Another thing that no one here knows or seems to be capable of understanding is the incredible load that thousands of simultaneous connections from each P2P user can place on an ISP’s routers and switches. This shit is expensive, and having to replace it once a year instead of once every five years does not make providers happy.
I know you all think that your ISP is somehow on a mission to defraud you of your money, and that they don’t want you to download pirated movies and whatnot. The truth of it is, at least from my experience, ISP’s don’t give a shit what you’re doing as long as it doesn’t impact other users on the network. They can’t be held responsible for you torrenting Sopranos, so stop thinking that they’re out to get you. The same exact thing applies to ISP’s that forbid users from running their own servers.
PLEASE, do a little research before you continue pissing and moaning about how unfair your ISP’s practices are!
FUCK!
- Tate[/quote]
This is quoted for truth.
[quote]
ISP’s don’t give a shit what you’re doing as long as it doesn’t impact other users on the network
[/quote]
Also, qft^
See you in the ether…^d
[quote comment="148857"][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]
Since you just typed it at the command-line, it will reset on reboot. I wouldn’t recommend messing around with ipfw manually unless you know what you are doing. Here’s a tutorial for you:
http://www.freebsd-howto.com/HOWTO/Ipfw-HOWTO
Too many people assume erroneously that most P2P traffic is illegal. As one example of a high volume, LEGITIMATE use of P2P, consider the sharing of lossless audio files among music fans. These files are legal recordings made at concerts with the permission of the performing bands (e.g., Grateful Dead, Dave Matthews, Govt Mule, Phil & Friends, John Mayer, Widespread Panic, etc.). They are also, for the most part, shared via a lossless compression format (primarily flac or shn files), which means that when uncompressed, the files retain all of the data, and therefore audio quality, of the original recording. A typical 2-3 hour concert will require approximately 1GB of storage media capacity. Consequently, it is very easy for fans of these “jambands” to acquire hundreds of gigabytes, if not terabytes of concert recordings, all of which can be and are actively and legally shared via P2P. If I’m not mistaken, this was the original point for the development of Azureus/Vuze.
To put this in perspective, if any of the same concerts were converted to mp3 format, the storage capacity required for the same 2-3 hour average concert would roughly equal 100 MB.
If you want some idea of the volume of concerts circulating legally, go to the music section of the Internet Archive, which also offers these same files for download via browser downloads. If you don’t want to do that, just think about how many Deadheads there are, and how many concerts the Dead played over 40 plus years, and that each year there are another group of teenagers that become Deadheads and just HAVE to HAVE that music.
Lots of LEGAL torrent files and filesharing, none of which anyone’s ISP has any business interfering with.
Tate you gobshite know what you’re talking about, right? Are you running an Internet Service? Are you a chadband lawyer? Are you an anti-share cunt? Blimey, people like you just make me sick.
Low capacity ISP?
Any possibility to change?
Tate:
You make a good argument about shared bandwidth and how bandwidth-hogging p2p software impacts other users, HOWEVER.. I still fail to understand how its *MY* fault that using the bandwidth I signed up for affects other users. *I* didnt build the (shared) infrastructure. If you cant provide a reliable 5mb pipe, then dont advertise a 5mb pipe. (and dont be subversive by filling your advertisement with small “fine print”.. that smacks of “used car salesman” tactics)
As far as high speed connections go,.. I certainly think tiered pricing and “a la carte” model would be much more fair and reasonable. If nothing else it would certainly get people aware of how much bandwidth they use, and to think more carefully about choices they make downloading. The only reason we’re so freaked out about an option like that is because we’ve been dealing with such a broken system for so long. Its very similar to gasoline prices rising due to market changes.
All things considered, we new a new broadband model (end to end gig+ fiber-optic). Our digital infrastructure seems to be in about the same shape as our bridges :)
http://findarticles.com/p/articles/mi_qn4188/is_20060327/ai_n16179217
Comcast CEO Brian Roberts salary in 2005 was 12.8 MILLION dollars (salary, compensation and other perks)
in 2004, his salary was 9.4 million.
“Roberts also entered into a four-year employment contract expiring in 2009 that gives him an annual base salary of $2.5 million, which may not be lowered unless it’s part of a plan to cut pay of senior executives. He also gets bonuses and other perks.”
I recognize that businesses need to make money, otherwise they wont be in business. But you also dont need to pay your CEO 12 farking millions dollars a year.
Wow what a CRAP page design! Black letters on a black background! Unreadble. Try again and do it right.
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