From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Schillstrom Subject: Re: [PATCH 1/1] netfilter: Add possibility to turn off netfilters defrag per netns Date: Wed, 4 Jan 2012 10:47:53 +0100 Message-ID: <201201041047.54579.hans.schillstrom@ericsson.com> References: <1325664443-10320-1-git-send-email-hans.schillstrom@ericsson.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Jozsef Kadlecsik , Patrick McHardy , Pablo Neira Ayuso , "netfilter-devel@vger.kernel.org" , "netdev@vger.kernel.org" , "hans@schillstrom.com" To: Jan Engelhardt Return-path: Received: from mailgw10.se.ericsson.net ([193.180.251.61]:48720 "EHLO mailgw10.se.ericsson.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754856Ab2ADJr5 (ORCPT ); Wed, 4 Jan 2012 04:47:57 -0500 In-Reply-To: Content-Disposition: inline Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Wednesday 04 January 2012 10:32:14 Jan Engelhardt wrote: > On Wednesday 2012-01-04 10:03, Jozsef Kadlecsik wrote: > > >On Wed, 4 Jan 2012, Hans Schillstrom wrote: > > > >> On Wednesday 04 January 2012 09:28:05 Jozsef Kadlecsik wrote: > >> > > >> > On Wed, 4 Jan 2012, Hans Schillstrom wrote: > >> > > >> > > In some cases it not desirable to have auto defrag. > >> > > Ex. in a cluster where packets can arrive on different blades. > >> > > In that case it is possible to use containers (LXC) and send > >> > > all fragments to one place where defrag is enabled. > >> > > > >> > > This patch makes it possible to turn off the defrag per network name space, > >> > > by setting net.netfilter.nf_conntrack_nodefrag to 1. > >> > > Both IPv4 and IPv6 is effected by this sysctl. > >> > > Default is 0 which is defrag. > >> > > >> > Conntrack assumes that the packets are defragmented and will drop any > >> > unfragmented one. So your patch results packet drops. > >> > >> Hmmm, more work... > >> > > >> > Also, if you want to disable defragmentation then why don't you simply > >> > "mark" the packets with the NOTRACK target? > >> > >> I don't think that will work since NF_IP_PRI_CONNTRACK_DEFRAG is -400 > > > >Then change NF_IP_PRI_RAW so that it precedes NF_IP_PRI_CONNTRACK_DEFRAG. > >The raw table should be made possible to completely override conntack and > >defrag is implicit part of the latter. > > We've been there (me in the thread even) - defrag is running before raw, > because otherwise you could not select packets based upon L4 > parameters for non-defrag in the first place: > > -t raw ... -p udp --dport 53 -j CT --notrack > > Not that I overly care about whether defrag is before/after raw.. > What about a mod param for ip{6}table_raw so it could be changed ? -- Regards Hans Schillstrom