From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: Re: [PATCH nf-next 0/9] netfilter: remove per-netns conntrack tables, part 1 Date: Thu, 5 May 2016 22:54:18 +0200 Message-ID: <20160505205418.GA21687@breakpoint.cc> References: <1461863628-23350-1-git-send-email-fw@strlen.de> <572BACA3.6070303@hpe.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Florian Westphal , netfilter-devel@vger.kernel.org, netdev@vger.kernel.org To: Brian Haley Return-path: Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:55390 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755918AbcEEUyW (ORCPT ); Thu, 5 May 2016 16:54:22 -0400 Content-Disposition: inline In-Reply-To: <572BACA3.6070303@hpe.com> Sender: netfilter-devel-owner@vger.kernel.org List-ID: Brian Haley wrote: > Openstack networking creates virtual routers using namespaces for isolation > between users. VETH pairs are used to connect the interfaces on these > routers to different networks, whether they are internal (private) or > external (public). In most cases NAT is done inside the namespace as > packets move between the networks. > > I've seen cases where certain users are attacked, where the CT table is > filled such that we start seeing "nf_conntrack: table full, dropping packet" > messages (as expected). But other users continue to function normally, > unaffected. Is this still the case - each netns has some limit it can't > exceed? The limit is global, the accounting per namespace. If the bucket count (net.netfilter.nf_conntrack_buckets) is high enough to accomodate the expected load and noone can create arbitrary number of net namespaces things are fine. I haven't changed the way this works yet because I did not have a better idea so far.