netdev - Re: [RFC PATCH 0/2] Faster/parallel SYN handling to mitigate SYN floods

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Date:	Wed, 30 May 2012 10:53:08 +0200
From:	Christoph Paasch <christoph.paasch@...ouvain.be>
To:	Jesper Dangaard Brouer <brouer@...hat.com>
CC:	netdev@...r.kernel.org, Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Martin Topholm <mph@...h.dk>, Florian Westphal <fw@...len.de>,
	opurdila@...acom.com,
	Hans Schillstrom <hans.schillstrom@...csson.com>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [RFC PATCH 0/2] Faster/parallel SYN handling to mitigate SYN
 floods

On 05/30/2012 10:44 AM, Jesper Dangaard Brouer wrote:
>> > 
>> > Then the receiver will receive two SYN/ACK's for the same SYN with
>> > different sequence-numbers. As the "SYN cookie SYN-ACK" will arrive
>> > second, it will be discarded and seq-numbers from the first one will be
>> > taken on the client-side.
> I thought that the retransmitted SYN packet, were caused by the SYN-ACK
> didn't reach the client?

Or, if the SYN/ACK got somehow delayed in the network and the
SYN-retransmission timer on the client-side fires before the SYN/ACK
reaches the client.


Christoph


-- 
Christoph Paasch
PhD Student

IP Networking Lab --- http://inl.info.ucl.ac.be
MultiPath TCP in the Linux Kernel --- http://mptcp.info.ucl.ac.be
Université Catholique de Louvain
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