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
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The following, if turned into a *.bat file will monitor packet loss. I went from 100% packet loss with RST injectionsComcast servers down to about 6% after updating DD-WRT firewall rules from command.
*.bat application ****
@echo off SETLOCAL FOR /F “usebackq tokens=2 delims==” %%i IN (`netstat -s ^| find “Active Opens” ^| find /V “= 0″`) DO set /A CESTABL1=%%i FOR /F “usebackq tokens=2 delims==” %%i IN (`netstat -s ^| find “Passive Opens” ^| find /V “= 0″`) DO set /A CESTABL1=%CESTABL1%+%%i FOR /F “usebackq tokens=2 delims==” %%i IN (`netstat -s ^| find “Failed Connection Attempts” ^| find /V “= 0″`) DO set /A CESTABL1=%CESTABL1%-%%i FOR /F “usebackq tokens=2 delims==” %%i IN (`netstat -s ^| find “Reset Connections” ^| find /V “= 0″`) DO set /A CRESETS1=%%i SET /A TESTCYCLE=0 SET /A TESTMINS=0 cls echo results will begin to be reported shortly, echo please wait or use Ctrl-c to quit… :repeatcycle ping -n 9 localhost >nul FOR /F “usebackq tokens=2 delims==” %%i IN (`netstat -s ^| find “Active Opens” ^| find /V “= 0″`) DO set /A CESTABL2=%%i FOR /F “usebackq tokens=2 delims==” %%i IN (`netstat -s ^| find “Passive Opens” ^| find /V “= 0″`) DO set /A CESTABL2=%CESTABL2%+%%i FOR /F “usebackq tokens=2 delims==” %%i IN (`netstat -s ^| find “Failed Connection Attempts” ^| find /V “= 0″`) DO set /A CESTABL2=%CESTABL2%-%%i FOR /F “usebackq tokens=2 delims==” %%i IN (`netstat -s ^| find “Reset Connections” ^| find /V “= 0″`) DO set /A CRESETS2=%%i SET /A TESTCYCLE=%TESTCYCLE%+1 SET /A TESTMINS=%TESTCYCLE% / 6 SET /A TESTSECS=%TESTCYCLE%%%6*10 IF %TESTSECS% EQU 0 SET TESTSECS=00 SET /A CESTABL=%CESTABL2%-%CESTABL1% SET /A CRESETS=%CRESETS2%-%CRESETS1% SET /A PCTRST=(%CRESETS% * 100)/%CESTABL% ECHO %TESTMINS%:%TESTSECS% - %CRESETS% out of %CESTABL% connections reset (%PCTRST%%%) [Ctrl-c quit] goto repeatcycle
Router commands ***
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -i lo -j ACCEPT
#Comcast BitTorrent seeding block workaround
-A INPUT -p tcp –dport 44936 –tcp-flags RST RST -j DROP
-A INPUT -m state –state ESTABLISHED,RELATED -j ACCEPT
#BitTorrent
-A INPUT -m state –state NEW -m tcp -p tcp –dport 44936 -j ACCEPT
-A INPUT -m state –state NEW -m udp -p udp –dport 44936 -j ACCEPT
-A INPUT -j REJECT –reject-with icmp-host-prohibited
COMMIT
As far as i know in the sates verizon DSL doesn’t throttle p2p shareing.
Comcast got me. They sent me the dreadded “Notice of Action under the Digital Millennium Copyright Act” email.
I’m outta here. I don’t like being watched. I encourage everyone to drop Comcast and let’s break up this monopoly. The worst part is losing your freedom…what’s next…actually turning over our information so we can get sued? No thanks.
Later f*ckwads
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Quit trying to draw attention to your crappy website. This is about Comcast infringing on our constitutional rights.
It’s like phone companies restricting your calls. Stupidity!
Aussies have had to deal with this for years, up until now I have been jealous of other countries ISPs. Currently I have a 25g peak and 45 gig off peak limit before we are shaped to dial up speed grr on a 1.5 mb/256kb line of course depending on what I am connected to I can be over limit in 7 days (Usenet is the fastest way lol).
My previous ISP was similar ( I was loyal for 4 years) but then started charging new customers for uploads!! And even though this never effected me I was so disgusted I took my money elsewhere.
If one company is doing it you can bet ya buck it will spread to all.
hey comcast eat a dick, youll never stop file sharing, you think just cuz you throttle you will stop it? hahahhahahahahhhaaahahahahahahhaa
get a brain fuckholes
[quote comment="315466"]Comcast got me. They sent me the dreadded “Notice of Action under the Digital Millennium Copyright Act” email.
I’m outta here. I don’t like being watched. I encourage everyone to drop Comcast and let’s break up this monopoly. The worst part is losing your freedom…what’s next…actually turning over our information so we can get sued? No thanks.
Later f*ckwads[/quote]
scan a picture of your big cock, and send it too them with a notice that they could suck it for all you care, and that they are faggot niggers.
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