From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [RFC PATCH 2/2] tcp: Early SYN limit and SYN cookie handling
 to mitigate SYN floods
Date: Thu, 31 May 2012 16:09:21 +0200
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Cc: Rick Jones <rick.jones2@hp.com>, Andi Kleen <andi@firstfloor.org>,
	Jesper Dangaard Brouer <jbrouer@redhat.com>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
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To: Hans Schillstrom <hans.schillstrom@ericsson.com>
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On Thu, 2012-05-31 at 10:45 +0200, Hans Schillstrom wrote:

> I can see plenty "IPv4: dst cache overflow"
> 

This is probably the most problematic problem in DDOS attacks.

I have a patch for this problem.

Idea is to not cache dst entries for following cases :

1) Input dst, if listener queue is full (syncookies possibly engaged)

2) Output dst of SYNACK messages.