BitTorrent Developers Introduce Comcast Busting Encryption
Written by Ernesto on February 15, 2008Several BitTorrent developers have joined forces to propose a new protocol extension with the ability to bypass the BitTorrent interfering techniques used by Comcast and other ISPs. This new form of encryption will be implemented in BitTorrent clients including uTorrent, so Comcast subscribers are free to share again.
BitTorrent throttling is not a new phenomenon, ISPs have been doing it for years. When the first ISPs started to throttle BitTorrent traffic most BitTorrent clients introduced a countermeasure, namely, protocol header encryption. This was the beginning of an ongoing cat and mouse game between ISPs and BitTorrent client developers, which is about to enter new level.
Unfortunately, protocol header encryption doesn’t help against more aggressive forms of BitTorrent interference, like the Sandvine application used by Comcast. A new extension to the BitTorrent protocol is needed to stay ahead of the ISPs, and that is exactly what is happening right now.
Back in August we were the first to report that Comcast was actively disconnecting BitTorrent seeds. Comcast of course denied our allegations, and ever since there has been a lot of debate about the rights and wrongs of Comcast’s actions. On Wednesday, Comcast explained their BitTorrent interference to the FCC in a 57-page filing. Unfortunately they haven’t stopped lying yet, since they now argue that they only delay BitTorrent traffic, while in fact they disconnect people, making it impossible for them to share files with non-Comcast users.
In short, the Comcast interference works like this: A few seconds after you connect to someone in a BitTorrent swarm, a peer reset message (RST flag) is sent by Comcast 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.
For the networking savvy people among us, here’s an example of real RST interference (video) on a regular BitTorrent connection. In this case, the reset happens immediately after the bitfields are exchanged. Evil? Yes - but there is hope.
The goal of this new type of encryption (or obfuscation) is to prevent ISPs from blocking or disrupting BitTorrent traffic connections that span between the receiver of a tracker response and any peer IP-port appearing in that tracker response, according to the proposal.
“This extension directly addresses a known attack on the BitTorrent protocol performed by some deployed network hardware. By obscuring the ip-port pairs network hardware can no longer easily identify ip-port pairs that are running BitTorrent by observing peer-to-tracker communications. This deployed hardware under some conditions disrupts BitTorrent connections by injecting forged TCP reset packets. Once a BitTorrent connection has been identified, other attacks could be performed such as severely rate limiting or blocking these connections.”
So, the new tracker peer obfuscation technique is especially designed to be a workaround for throttling devices, such as the Sandvine application that Comcast uses. More details on the proposal can be found at BitTorrent.org, which aims to become a coordination platform for BitTorrent developers.
TorrentFreak talked to Ashwin Navin, president and co-founder of BitTorrent Inc. who has some of his employees working on the new extension. He told us: “There are some ISPs who would like people to believe that “slowing down” BitTorrent or “metering” bandwidth consumption serves the greater good. Consumers should be very weary of this claim.”
“In recent months, consumers enjoyed unprecedented participation in the political process thanks to the ability to upload opinions and feedback in the YouTube presidential debates. Musicians, filmmakers and artists are finding ways to connect with their audiences across the world thanks to MySpace and BitTorrent. Students are engaging with interactive learning tools in their schools. Which bandwidth intensive application will banned or shaped or metered next by these ISPs? The creative spirit of millions has been ignited, and our need to participate, to communicate will not be silenced.”
“The US government should encourage ISPs to innovate and invest in their networks,” Ashwin said. “Permitting them to interfere or interrupt in the communications of consumers, to protect ISP profit margins, would be a tremendous set back for our country and economy, when we are already slipping behind the first world (UK, EU, Japan, Korea, Singapore, etc) in its broadband capacity.”
We wholeheartedly agree with Ashwin on this one, as we’ve said before. The Internet is only a few years old, if the plan is to keep using it in the future, ISPs need to upgrade their networks. So, invest in more Internet gateway capacity, 10Gbps interconnect ports, and peering agreements. BitTorrent users are not the problem, they only signal that the ISPs need to upgrade their capacity, because customers will only get more demanding in the future. The Internet is not only about sending email, and browsing on text based websites anymore.
The new protocol extension is still under development, but the goal is of course, to get it out as soon as possible.
Hang on…
Previously: Village People Hire Web Sheriff for Assault on The Pirate Bay, ABBA on Standby
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114 Responses
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marijuana for life!
Yes it is. Even the very rudimentary ARPANET is not over 40 years old yet.
Excellent!
It should be noted that if you download a torrent file over an unencrypted connection, the attacker could know the shared secret of this obfuscation protocol.
Thus everyone affected by throttling should make sure to download their torrent files over HTTPS.
Websites that provide torrent files should make that option available, or even default.
46- awesome idea imo
I could kiss you.
in Argentina we have the same problems, at PRIMA S.A. (Flash Multicanal) they use netenforcer hardware and kill our connection at day time… we can download about 2.1 GB per night… KILL THEM PLEASE!
useless.
emule did such implement also but only manage to last not even a year before isp find the solution
[quote comment="291161"]File sharing increases the load on the networks so users who share files should pay for the bandwidth they use. This is the only way ISPs can finance network capacity increase.[/quote]
Hmm.. Funny European ISPs dont need to do that. Look at sweden 80% bandwith is used for filesharing the ISPs are doing great!
I think the flaw is somewhere else, not bandwith but greed and pressure..
Just part of a normal arms race, except what’ll happen at some point is that you get what you wish for and all the ISPs using this technology stop doing so (saving equipment $). Then they move to metered pricing so that they truly do not care what you use your IP connection for — and in fact want you to use more as it generates more money for them. Then a lot of people using torrents won’t want to anymore, because it’ll cost them a lot more than they’re paying. And once one ISP breaks out of flat-rate pricing, they’ll all rush to it because it’ll be more profitable.
To all Comcast Users - Change your ISP and say goodbye to Comcast! This company sucks.
Has anyone actually tried whether dropping RST packets on both sides helps? I think Sandvine sends 20x RST to both sides and drops the actual TCP packet, but TCP recovers from dropped packets, so ignoring the RST packets should work albeit there’d still be some throttling effect. While it’s not possible for application layer software to avoid that the TCP/IP stack handles the RST and resets the connection, the software can notice the RST by looking at the error code. Therefore you could simply aggressively re-establish connections which are reset. This would also have the effect which someone mentioned here. If the ISP tries to inject RSTs, they’ll just make it worse for themselves because it will result in a flood of connection attempts.
It’s kinda interesting that nobody mentions UDP as an option. You can’t really modify TCP because it’s officially standardized and the operating system handles it, leaving very little control to the applications using it - which of course is the idea and usually a good thing. However, it’s not difficult to design a TCP-like protocol over UDP, you could in fact tunnel TCP over UDP. Then all you have to do is adding a little modification that makes it impossible - or at least very difficult - that a connection can be trivially reset.
I find it really odd that neither ed2k or bittorrent support file transfers over UDP because it has several advantages especially in today’s NAT-crippled internet. There are disadvantages too but none of them are so bad, that it justifies complete ignorance of this option.
this could be awesome
Getting rid of Comcast isn’t an option for me. They are EVERYWHERE :(
Awesome!
[quote comment="291496"]To all Comcast Users - Change your ISP and say goodbye to Comcast! This company sucks.[/quote]
Your stupidity is showing.
@59 - (quoting Wikipedia)
“The UDP tracker is better optimized and puts less strain on the tracking server, however it is not supported by all BitTorrent clients. On the other hand the HTTP tracker is supported by all BitTorrent clients, is more reliable for ratio updates, but more of a strain on the server. Neither tracker has any effect on transfer speeds, except that if a user wanted to use a web browser (transfers via HTTP) then the UDP downloads would not be as affected by the increase in local traffic.”
Now you know.
i’m psyched about this. the exact same thing happens to me on my cox connection, but only when uploading, not downloading.
64, you didn’t understand a single word I wrote. I’m very well aware of DHT and UDP trackers but this absolutely nothing to do with what I wrote. I wouldn’t quote Wikipedia to save my life because it’s full of shit, misinformation and it’s getting worse with every edit.
So when are we going to get it?
Great Job To the dev team! keep it up
While Comcast wastes there profits in a traffic shaping battle. Other isps are making better faster networks useing fiber optics. They are shooting themselves in the foot
People Listen to Me I busted through Comcast with a modem fix my daughters boyfriend did for me, I seed I seedI seed I Dl and I Dl no interferance-Any TV repair shop can do it also any electronics student can too..
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