From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Paasch Subject: Re: [RFC PATCH 0/2] Faster/parallel SYN handling to mitigate SYN floods Date: Wed, 30 May 2012 10:53:08 +0200 Message-ID: <4FC5DFF4.1020604@uclouvain.be> 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> Reply-To: christoph.paasch@uclouvain.be Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, Eric Dumazet , "David S. Miller" , Martin Topholm , Florian Westphal , opurdila@ixiacom.com, Hans Schillstrom , Andi Kleen To: Jesper Dangaard Brouer Return-path: Received: from smtp.sgsi.ucl.ac.be ([130.104.5.67]:48596 "EHLO smtp6.sgsi.ucl.ac.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932368Ab2E3IxO (ORCPT ); Wed, 30 May 2012 04:53:14 -0400 In-Reply-To: <1338367497.7747.72.camel@localhost> Sender: netdev-owner@vger.kernel.org List-ID: On 05/30/2012 10:44 AM, Jesper Dangaard Brouer wrote: >> >=20 >> > Then the receiver will receive two SYN/ACK's for the same SYN with >> > different sequence-numbers. As the "SYN cookie SYN-ACK" will arriv= e >> > second, it will be discarded and seq-numbers from the first one wi= ll be >> > taken on the client-side. > I thought that the retransmitted SYN packet, were caused by the SYN-A= CK > 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 --=20 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 Universit=C3=A9 Catholique de Louvain --=20