From: Patrick McHardy <kaber@trash.net>
To: Harald Welte <laforge@netfilter.org>
Cc: Don Cohen <don-netf@isis.cs3-inc.com>,
netfilter-devel@lists.netfilter.org, netdev@oss.sgi.com
Subject: Re: Possible ip_defrag DoS ?
Date: Sun, 16 Feb 2003 21:26:04 +0100 [thread overview]
Message-ID: <3E4FF3DC.7090408@trash.net> (raw)
In-Reply-To: <20030216201154.GA30787@sunbeam.de.gnumonks.org>
Harald Welte wrote:
>On Sun, Feb 16, 2003 at 01:38:56PM +0100, Patrick McHardy wrote:
>
>
>
>>inerestingly, it seems linux defragmentation is vulnerable to dos attack.
>>the evictor (called before defragmentation) just kills the oldest entry
>>of each hash slot, starting with 0 until memory is below
>>sysctl_ipfrag_low_thresh. by sending enough fragments
>>(>sysctl_ipfrag_high_thresh) which hash to the highest bucket you can
>>stop reassembly of valid packets.
>>
>>
>
>I'm forwarding this (from netfilter-devel) to the linux networking
>developers at netdev@oss.sgi.com. If your assumption is valid, they
>might want to have a look at this...
>
>thanks.
>
>
>
>
Hi Harald, it seems this was not (entirely) correct, the evictor only
kills the last
member of each hash slot and then moves on. still, assuming the hash
function is good
there is a good chance we can disturb reassembly noticeable.
Patrick
prev parent reply other threads:[~2003-02-16 20:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20030215232635.25928.78900.Mailman@kashyyyk>
[not found] ` <15950.60635.389199.836425@isis.cs3-inc.com>
[not found] ` <3E4F0881.70302@trash.net>
[not found] ` <15951.10496.914173.716313@isis.cs3-inc.com>
[not found] ` <3E4F8660.5020409@trash.net>
2003-02-16 20:11 ` Possible ip_defrag DoS ? Harald Welte
2003-02-16 20:26 ` Patrick McHardy [this message]
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