[21524] in bugtraq
Re: Small TCP packets == very large overhead == DoS?
daemon@ATHENA.MIT.EDU (Pavel Machek)
Mon Jul 16 01:18:21 2001
Date: Mon, 9 Jul 2001 11:59:28 +0000
From: Pavel Machek <pavel@ucw.cz>
To: Darren Reed <avalon@coombs.anu.edu.au>
Cc: bugtraq@securityfocus.com
Message-ID: <20010709115928.B38@toy.ucw.cz>
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In-Reply-To: <200107071547.BAA00642@caligula.anu.edu.au>; from avalon@coombs.anu.edu.au on Sun, Jul 08, 2001 at 01:47:21AM +1000
Hi!
> If any of you have tested what happens to the ability of a box to
> perform well when it has a small MTU you will know that setting the
> MTY to (say) 56 on a diskless thing is a VERY VERY bad idea when NFS
> read/write packets are generally 8k in size. Do not try it on a NFS
> thing unless you plan to reboot it, ok ? Last time I did this was
> when I worked out you could fragment packets inside the TCP header
> and that lesson was enough for me ;_)
AFAI can remember, there's minimum MTU defined for IP (something like 576)...
...and then there are networks like hamradio that use lower MTU. They are
really non-compliant, but Linux wants them to work.
Pavel
--
Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt,
details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html.
