[Infowarrior] - BitTorrent Developers Introduce Comcast Busting Encryption

[Richard Forno]

BitTorrent Developers Introduce Comcast Busting Encryption
Written by Ernesto on February 15, 2008
http://torrentfreak.com/bittorrent-devs-introduce-comcast-busting-encryption
-080215/

Several 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 doesn¹t 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
Comcast¹s actions. On Wednesday, Comcast explained their BitTorrent
interference to the FCC in a 57-page filing. Unfortunately they haven¹t
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, here¹s 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.

³This 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.²

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:
³There are some ISPs who would like people to believe that ³slowing down²
BitTorrent or ³metering² bandwidth consumption serves the greater good.
Consumers should be very weary of this claim.²

³In 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.²

³The US government should encourage ISPs to innovate and invest in their
networks,² Ashwin said. ³Permitting 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.²

We wholeheartedly agree with Ashwin on this one, as we¹ve 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.