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Message-ID: <4BD1A755.1020201@trash.net>
Date: Fri, 23 Apr 2010 15:57:41 +0200
From: Patrick McHardy <kaber@...sh.net>
To: Jesper Dangaard Brouer <hawk@...u.dk>
CC: Eric Dumazet <eric.dumazet@...il.com>,
Changli Gao <xiaosuo@...il.com>, hawk@...x.dk,
Linux Kernel Network Hackers <netdev@...r.kernel.org>,
netfilter-devel@...r.kernel.org,
Paul E McKenney <paulmck@...ux.vnet.ibm.com>
Subject: Re: DDoS attack causing bad effect on conntrack searches
Jesper Dangaard Brouer wrote:
> On Fri, 23 Apr 2010, Patrick McHardy wrote:
>
>> That sounds like a good idea. But lets what for Jesper's test results
>> before we start fixing this problem :)
>
> I will first have time to perform the tests Monday or Tuesday.
>
> BUT I have just noticed there seems to be a corrolation between
> conntrack early_drop and searches. I have upload a new graph:
>
> http://people.netfilter.org/hawk/DDoS/2010-04-12__001/conntrack_early_drop002.png
I guess that's somewhat expected when your conntrack table is full
and all you're seeing is new connection setup attempts.
First you have a search for an existing conntrack, then it attempts
to create a new one and tries to early_drop and old one.
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