From: Florian Weimer <fw@deneb.enyo.de>
To: Valdis.Kletnieks@vt.edu
Cc: Willy Tarreau <willy@w.ods.org>,
Miquel van Smoorenburg <miquels@cistron.nl>,
linux-kernel@vger.kernel.org
Subject: Re: TCP-RST Vulnerability - Doubt
Date: Tue, 29 Jun 2004 23:22:56 +0200 [thread overview]
Message-ID: <87brj212kv.fsf@deneb.enyo.de> (raw)
In-Reply-To: <200406292003.i5TK3Y6o017275@turing-police.cc.vt.edu> (Valdis Kletnieks's message of "Tue, 29 Jun 2004 16:03:34 -0400")
* Valdis Kletnieks:
> The latest numbers I saw on the NANOG list estimated that only 30%
> to 40% of core peerings were using MD5 even several weeks after the
> Great MD5-Fest...
30% to 40% is extremely high. Are you sure these numbers are correct?
> I am told that at least some versions of IOS got it Very Very Wrong
> - rather than first checking the simple things like "is the
> source/dest addr/ports/seq on the RST in bounds?" or "is a BGP
> packet?", it would check the MD5 *first* - meaning you could swamp
> the real CPU by sending it a totally bogus stream of allegedly
> MD5-signed traffic..
I think the MD5 option is designed to be processed *before* semantic
analysis of the TCP header. This way, it will protect the router in
case of TCP header parsing bugs. So it's not "Very Very Wrong", just
a different trade-off.
next prev parent reply other threads:[~2004-06-29 21:23 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-25 21:20 TCP-RST Vulnerability - Doubt saiprathap
2004-06-25 22:05 ` David S. Miller
2004-06-26 2:22 ` Andre Tomt
2004-06-28 19:18 ` Florian Weimer
2004-06-28 13:22 ` Miquel van Smoorenburg
2004-06-28 14:49 ` Chris Wedgwood
2004-06-28 18:34 ` Florian Weimer
2004-06-28 18:37 ` Willy Tarreau
2004-06-28 19:26 ` Florian Weimer
2004-06-29 20:03 ` Valdis.Kletnieks
2004-06-29 21:22 ` Florian Weimer [this message]
2004-06-29 21:45 ` Valdis.Kletnieks
2004-06-29 2:34 ` Daniel Roesen
2004-06-29 21:28 ` Florian Weimer
2004-06-29 2:34 ` Lincoln Dale
2004-06-29 21:27 ` Florian Weimer
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