Date: Wed, 14 Nov 2007 08:48:18 +0100 From: cpghost <cpghost@cordula.ws> To: Robert Huff <roberthuff@rcn.com> Cc: questions@freebsd.org Subject: Re: How to reset a TCP connection Message-ID: <20071114084818.377cb6c8@epia-2.farid-hajji.net> In-Reply-To: <18234.26375.844671.397739@jerusalem.litteratus.org> References: <200711140234.lAE2Ykp9016352@banyan.cs.ait.ac.th> <18234.24690.239824.947693@jerusalem.litteratus.org> <18234.25217.475159.615201@jerusalem.litteratus.org> <18234.26375.844671.397739@jerusalem.litteratus.org>
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On Tue, 13 Nov 2007 22:09:59 -0500
Robert Huff <roberthuff@rcn.com> wrote:
> Robert Huff writes:
>
> > > Olivier Nicole writes:
> > >
> > > > How can I manually reset an established TCp connection?
> > >
> > > Ask Comcast. :-)
>
> My apologies for being cryptic.
> In the United Stated, cable television and Internet provider
> Comcast has recently come under criticism for "managing" bittorrent
> traffic by sending TCP RST packets to those who are over some
> unannounced traffic limit (i.e. hogging the bandwidth).
This reminds me of an old bug ("sniper bug"):
http://net.tamu.edu/tamunet/announce/1995/19950825-151018.html
I've had a setup with those NICs on a university network
in the '95, and those machines' TCP/IP stack kept wildly
and seemingly randomly shooting down TCP connections between
unrelated Unix hosts (sic!) with TCP RST packets (we've still
had unswitched Ethernet, even a 10-base-5 yellow snake in
the data center with a few PCs tapped on it). It nearly drove
me nuts until I've intercepted and detected those spurious
TCP RST packets with a sniffer (and at first, the sniffer
machine had also one of those buggy NICs, go figure!)
So Comcast is doing it all over again? Shooting down connections
from the middle? Crazy nasty folks over there!
A short-term fix is to filter out TCP RST packets at the
firewall, and let TCP connections time out, even though it
could waste a lot of kernel memory on busy nodes.
cpghost.
--
Cordula's Web. http://www.cordula.ws/
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