From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: [RFC PATCH 0/2] Faster/parallel SYN handling to mitigate SYN floods Date: Thu, 31 May 2012 15:04:23 +0200 Message-ID: <1338469463.7747.167.camel@localhost> References: <20120528115102.12068.79994.stgit@localhost.localdomain> <4FC3A465.4030203@uclouvain.be> <1338322661.7747.17.camel@localhost> <4FC53353.2050801@uclouvain.be> <1338367497.7747.72.camel@localhost> <4FC5DFF4.1020604@uclouvain.be> <1338417630.7747.156.camel@localhost> <1338468693.7747.162.camel@localhost> <1338469100.2760.1341.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: christoph.paasch@uclouvain.be, netdev@vger.kernel.org, "David S. Miller" , Martin Topholm , Florian Westphal , Hans Schillstrom , Andi Kleen To: Eric Dumazet Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47532 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756853Ab2EaNEv (ORCPT ); Thu, 31 May 2012 09:04:51 -0400 In-Reply-To: <1338469100.2760.1341.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2012-05-31 at 14:58 +0200, Eric Dumazet wrote: > On Thu, 2012-05-31 at 14:51 +0200, Jesper Dangaard Brouer wrote: > > 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. > > > > How many different IP addresses are used by your generator ? In this attack I reduced the IPs to 255, and also the source port numbers, and then simply cloned some of the SKBs. But normally I use 65535 IPs 198.18.0.0/16 (the range reserved for benchmarking). > Or maybe you disabled IP route cache ? Why do you think I have disabled the IP dst route cache?