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

From: Jesper Dangaard Brouer <[email-masked]>
Date: Thu, 31 May 2012 14:51:33 +0200

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