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

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Message-ID: <1338468693.7747.162.camel@localhost>
Date:	Thu, 31 May 2012 14:51:33 +0200
From:	Jesper Dangaard Brouer <jbrouer@...hat.com>
To:	christoph.paasch@...ouvain.be
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>,
	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 Thu, 2012-05-31 at 00:40 +0200, Jesper Dangaard Brouer wrote:
> That seems like a very unlikely situation, which we perhaps should
> neglect as we are under SYN attack.
>
> I will test the attack vector, if we instead of dropping the reqsk,
> fall back into the slow locked path.

I can provoke this attack vector, and performance is worse, if not
dropping the reqsk early.

Generator SYN flood at 750Kpps, sending false retransmits mixture.

- With early drop: 406 Kpps
- With return to locked processing: 251 Kpps

Its still better than the approx 150Kpps, without any patches.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer

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