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