Messages in this thread | | | Subject | Re: Update: Subtle data corruption of TCP streams | Date | Sat, 25 Mar 2000 00:20:12 -0500 (EST) | From | (Wietse Venema) |
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Seems that routers don't do the packet rewriting that I'm observing here. It's the domain of bandwith management systems. There are at least four players. I got reactions from several.
Disabling TCP options in the Linux kernel does help, especially when you're talking to non-Linux systems.
Wietse
Austin Schutz: > [bugtraq removed from cc:] > > I've noticed this problem on my network. I'm behind an Ascend > pipeline 50. I had thought that this might be the root of the problem. > Supposedly there's something similar reported as a problem with older > ascend software. > > Any idea what the other people experiencing the prolbem are using > as gateway routers? > > Austin > On Fri, Mar 24, 2000 at 04:26:13PM -0800, Blu3Viper wrote: > > How about taking this to linux-kernel for discussion since it appears to be > > a development kernel bug possibly? > > > > -d > > > > On Fri, 24 Mar 2000, Wietse Venema wrote: > > > > > Date: Fri, 24 Mar 2000 10:38:36 -0500 > > > From: Wietse Venema <wietse@PORCUPINE.ORG> > > > To: BUGTRAQ@SECURITYFOCUS.COM > > > Subject: Update: Subtle data corruption of TCP streams > > > > > > Apparently, once instance of this data corruption problem is caused > > > by an unnamed bandwidth management system. It runs as a bridge, > > > and does not show up in traceroute etc. output. We were able to > > > estimate its location (at 5 ms round-trip time from one endpoint) > > > by analyzing packet arrival times. > > > > > > Until now, this TCP data corruption problem has been observed only > > > when one of the connection endpoints runs a recent LINUX version. > > > Sightings have been reported by sites in Germany and in France. > > > > > > Only recent LINUX versions request the use of timestamp options > > > that cause the tell-tale patterns of "01 01 08 0a" in TCP packets, > > > and that end up being regurgitated as ^A^A^H^J data. > > > > > > I have updated the analysis at ftp://ftp.porcupine.org/pub/debugging/ > > > > > > Wietse > > > > > > Wietse Venema: > > > > This note is about a subtle data corruption problem with TCP data > > > > streams that may bite people as more and more (LINUX) systems are > > > > sending network traffic with TCP-level options turned on. > > > > > > > > Last week, several Postfix users reported mail delivery failures > > > > because sequences of control characters (for example, ^A^A^H) were > > > > being inserted into their SMTP connections, resulting in SMTP > > > > protocol errors and non-delivery of email. > > > > > > > > These data corruption problems are not host specific: they are > > > > observed with both Linux and BSD/OS systems, and with mail sent to > > > > and/or received from systems running Postfix, Sendmail and qmail. > > > > > > > > Over the weekend of March 18, 2000, a few people left tcpdump > > > > running on their machines, in order to record some of these corrupted > > > > SMTP sessions. This note is based on an analysis of that data. > > > > > > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.rutgers.edu > > Please read the FAQ at http://www.tux.org/lkml/ > >
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