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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[quote comment="149035"]> 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]
ummm that is not correct as far as I can tell since comcast is only doing this to their customers on their network. So all the other peers world wide not on comcast are not facing this issue so this will let you connect to them and stay connected.
[quote comment="149187"]Wow what a CRAP page design! Black letters on a black background! Unreadble. Try again and do it right.[/quote]
???????????
What page? This page is fine. The link directly above your post is fine. What are you smoking?
[quote comment="148523"]“iptables -A INPUT -p tcp –dport $TORRENT_CLIENT_PORT –tcp-flags RST RST -j DROP
is the solution, and soon torrent clients / peerguardian and alike hopefully implements it for windows aswell =)”
Is there any way to get this to work on a windows network through ICS with a server instead of a router??[/quote]
Yep. Use Linux instead. I’m running Kubuntu (Ubuntu that looks more like Windows), and it’s great.
[quote comment="148770"]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]
Glad to help. Here’s your solution:
http://www.kubuntu.org
That’s what I use. I was a MS Windows user for years before I switched. You can do all sorts of neat things with packets (including BitTorrent packets) with Linux that Windows simply doesn’t let you do.
Oh, and your virus threat goes way down, too, as a nice side benefit.
if I find that comcast is throttling my home connection when I get back from travel on monday, they will be getting more than just nastygrams and lost business.
[quote comment="149329"]if I find that comcast is throttling my home connection when I get back from travel on monday, they will be getting more than just nastygrams and lost business.[/quote]
VD? :-)
Tate has some good points but I can’t help thinking he works for the RIAA.
Try Usenet people - Bittorrent is dead for me.
I can still seed to non Comcast ips so maybe you have to be flagged as heavy user or something.
My Comcast upload speeds have gone into the crapper in the last week. I pay Comcast $70 a month for 8.0 mbps downloads and 756 upload speeds. Since Comcast has pretty much eliminated file sharing on their network, i downgraded my service to 4mbps at $56 a month until i find a new provider who believes in growing a network to meet demand not stifle existing connections to minimize traffic on their network. I hope Verizon Internet access is available in my area (sales office closed today), if not i will go with Dircttv and AT&T access with 6mpbs download 756mpbs uploads at only $34.95 a month. That is one half of what I am currently paying Comcast who won’t let me file share. Why would anyone need 8mpbs 768mpbs High Speed Access for $70 if you can’t file share. To download emails faster? Come on. I am sort of glad Comcast pissed me off, it force me to look at other isps in my area and realize potential savings of $35 a month or $400 a year. More and more legal sites are using bit torrent to sell movies and music downloads, yet obvioulsy Comcast refuses to recognize this fact. Hollywood has alreay started a few bittorent sites to sell current movies but on a comcast network. these sites won’t have any comcast seeders.
Again, if you have the $70 comcast package change to the 56.00 package. You won’t tell the difference. In the meantime look for another ISP - Verizon is rated the best. Go with them. Screw Comcast I hope they lose a significant number of users this quater. I bet Comcast sales revenue the 4th quarter of 2007 will be lower than the 4th quarter of 2006. If we can make this happen and force Comcast stock to take a dive on wall street would be sweet revenge.
[quote comment="148970"]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 [/quote]
Tate, you’re right that all these things are expensive, but ISPs (all of them) keep saying they’re upping their bandwidth to astronomical levels. If they can’t do it, then they shouldn’t advertise it that way.
They should advertise Minimum Upload and Download rates. There is absolutley NO excuse for me to be unable to upload to etree (ok 1.7kb/s).
There’s no excuse for saying that upstream is now raised to 512kbs, when A) you can never EVER get that rate and B) you can’t get even get the 384kbs they were advertising before.
I don’t mind prioritizing, but advertise up front what the minimum is, so I can make an informed decision. Advertising up to 1.2 Gigabytes Upstream (in microscopic print it says if everyone in the world, aside from you, is knocked off the internet) is just a lie. You’ll never EVER get it. I’ve never gotten 5 or 6mb downloads. I’m lucky if I can hit 2mb (even in the middle of the night).
My experience with Comacast is not good. I’ve had them in 2 different states, and they were awful the first place and here they were so-so until the last few days.
This is what I think happen. Comcast has been growing its internet service not by attracting new customers but by buying their competitors. By doing so, there debt is at a all-time high of about 29,000,000,000. They can’t grow the network because they don’t have the money to pay for the expansion. Comcast has oversold its network. It has too many coustomers and not enough broadband width. So if you can’t expand, you start limiting traffic on your network. Also, since Comcast sells on demand video, bittorents are a threat to that business. Comcast tries to contol internet content by preventing their customers to seed certain files so the bittorrent dies a quick death. If people can’t get their videos anymore from the internet, those fools at comcast believe they will sign on to On Demand services. However, most customers will not roll over and comply, and will sign up for another ISP.
Also just look at Comcast financials. This is one company I would not invest in. Even their emplyoees are not to eager to buy the stock at reduced prices. Fair value of a share of stock was 7.30 in 2006 down from $8.67 in 2005, so even though revenues increased the acquistion costs were even greater.
They have what Comcast calls Goodwill which is the excess of the acquisition cost of an acquired entity over the fair value of the identifiable net assets acquired. “Comcast evaluates
the recoverability of goodwill annually,” blah blah blah.
It sounds like they are making up assets by calling goodwill an asset of 14,000,000,000. It is determined by the difference in what they paid for a company and what its true value is. So if the company is worth less than what they paid for it would be counted as a goodwill asset. Sounds like vodoo accounting and I think Comcast spend a lot more than those comanpies real value. $14,000,000,000 too much.
They can’t change users behavior once habits are formed. People aren’t going to stop file sharing and sign up for Comcast in Demand. The internet has a much much better variety of videos than on demand will ever have.
I found out today, My parents are also dropping comcast not because of file sharing but becaise those advertised speeds, they never got over 1 mpbs from comcast even though they were promised 6. They like me has found comcast not to be user friendly. So screw them - hope their revenues go into the tank for the third and fourth quarter.
I have comcast and have had nothing but problems lately, not just with torrents, but in general. Torrents especially, I can connect to users, but get no download/upload at all.
CAN WE ALL SAY CENSORSHIP
TIME WARNER ROAD RUNNER HAD FOR 5 YRS
ZERO PROBLEM PERFECT UP TIME AN CUSTOMER SUPPORT ZERO PROBLEMS
4 MONTHS OF COMSPASTIC FIRST 4 WEEKS OF CABLE TV PROBLEMS THEM MY NET DIES EVERY FEW HOURS OF USE MAN I LOVE THESE PEOPLE IM THINKING OF JUST INVITING THEM OVER TO SHOOT ME THE PAIN WOULD BE A LOT QUICKER TO REMOVE
IS VERISON FIOS NOT ANTI AMERICAN LIKE THESE A HOLES - THIS IS INTER NET TERRORISM SO MUCH FOR WHAT THE INVERNTORS OF THE NET INTENDED IT THAT WE ALL LOVED SO LONG OPEN COMMUNICATION SO MUCH FOR MEET GREET EXPLORE SHARE AND GROW NOW ITS GET PAYED THINK WE ALL NEED TO FUND REARCH TO ANOTHER PLANET AND ALL MOVE THEIR THIS ONE IS GOING TO HADES IN A HAND BASKET ALLPOLITICAL PARTYS ARE NOW BIASED RICH OLD GOATS
AND BAGS WHO IF LEFT TO DEAL WITH WHAT WE ARE NOW DEALING WITH DUE TO THEIR IGNORANCE THEY WOULD WAKE UP.
VERIZON HERE I COME IF YOU OFFER NO BS PRIVACY TO YOUR CUSTOMER WHO PAYED YOUR SAL
I am tired of crap like this I get an advertised up to 5.0MB/s and I dont even get near 700Kb/s thats bull crap and now Comcast is throttling P2P f them. But then again verizon is fing crazy too i get a 1.5MB/s line for the same price that I get the comcast line at.
Also How does one even get 700KB/s on bittorent? I have never gotten more than 250kb/s on my 5mbit line.
Well, My Comcast service now doesn’t work at all - for even the web or email. It just stopped when downloading a torrent, and will not work either way - any bright ideas before I call them to cancel?
3 mbps / 8 = 375 kbps jackass
This is such a shame: Cache Logic is the customer-friendly way to manage bandwidth; my own ISP (Virgin Media, formerly NTL World) uses it.
http://robert.accettura.com/archives/2004/06/02/isps-should-run-bittorrent-caches/
Clearly, Comcast’s behaviour here begins from a mentality of punishing criminals. The fact that they’ve bought in a technical solution for packet detection shows that it’s not technical difficulty that has led them to eg. simple throttling. Rather, Comcast want to combine punishment with lock-in (since one can seed to Comcast’s own customers).
Greed and a desire to police has led to this result. This kind of throttling could lead to the creation of several internet islands, for it is the beginning of packet discrimination. The ISPs have their holy grail in sight: the aim of controlling both the user and the media.
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