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Message-ID: <20160505205418.GA21687@breakpoint.cc> Date: Thu, 5 May 2016 22:54:18 +0200 From: Florian Westphal <fw@...len.de> To: Brian Haley <brian.haley@....com> Cc: Florian Westphal <fw@...len.de>, netfilter-devel@...r.kernel.org, netdev@...r.kernel.org Subject: Re: [PATCH nf-next 0/9] netfilter: remove per-netns conntrack tables, part 1 Brian Haley <brian.haley@....com> 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.
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