[100216] in North American Network Operators' Group
RE: Comcast blocking p2p uploads
daemon@ATHENA.MIT.EDU (Andrew Odlyzko)
Fri Oct 19 16:38:03 2007
To: nanog@nanog.org
Date: Fri, 19 Oct 2007 14:59:42 -0500 (CDT)
From: odlyzko@dtc.umn.edu (Andrew Odlyzko)
Errors-To: owner-nanog@merit.edu
Has anyone (any lawyers here on the list?) investigated the legality
of this action? With the FCC eliminating common carriage limits on
ISPs, it seems that blocking traffic to/from particular IP addresses,
etc., is acceptable. But from this description of Comcast's activities,
it appears that they are using active measures to interfere with their
customers' actions (fooling their customers' equipment into believing the
machines at the other end have terminated the interactions). Could not
this be construed as violating DMCA and a dozen other laws that have been
invoked against malicious hackers?
Andrew Odlyzko
> On Fri Oct 19, Scott Berkman wrote:
I agree, they have been doing this in select locations for some time. I
live in Atlanta and have seen this happening for about the 3 months, but I
have friends in the suburbs that have (or had) no issues. I imagine they
have been deploying their traffic shaping in more and more headends. Here
is some actual operational details:
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.
Comcast is making no effort to determine if the traffic they are blocking
is legal or not. No one blocks all web traffic because some sites have
illegal content or questionable/undesired material.
Personally I think this is inappropriate behavior for an ISP and I hope it
causes a mass exodus of Comcast customers.
-Scott
-----Original Message-----
From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of
Clinton Popovich
Sent: Friday, October 19, 2007 3:02 PM
To: 'Steven M. Bellovin'; nanog@nanog.org
Subject: RE: Comcast blocking p2p uploads
This is old news man, that's been happening for at least 3 months now.
Clinton Popovich
Systems Administrator
Nauticom Internet Services - An NPSI Company
2591 Wexford-Bayne Road, Suite 400
Sewickley, PA 15143
Tel: 724-933-9540
Fax: 724-933-9888
Email: crpopovi@nauticom.net
Web: http://www.nauticom.net
-----Original Message-----
From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of
Steven M. Bellovin
Sent: Friday, October 19, 2007 2:51 PM
To: nanog@nanog.org
Subject: Comcast blocking p2p uploads
http://www.nytimes.com/aponline/technology/AP-Comcast-Data-Discrimination.
ht
ml
http://www.nytimes.com/aponline/technology/AP-Comcast-Data-Discrimination-
Te
sts.html
Not a lot more I can say, other than argghhh!
--Steve Bellovin, http://www.cs.columbia.edu/~smb