netdev - Re: [PATCH net-next] netfilter: nf_conntrack: introduce conntrack limit per-zone

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Date:   Wed, 23 Oct 2019 13:07:56 +0200
From:   Florian Westphal <fw@...len.de>
To:     Tonghao Zhang <xiangxia.m.yue@...il.com>
Cc:     Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        netfilter-devel@...r.kernel.org,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] netfilter: nf_conntrack: introduce conntrack
 limit per-zone

Tonghao Zhang <xiangxia.m.yue@...il.com> wrote:
> > openvswitch supports per zone limits already, using nf_conncount
> > infrastructure.
> This path limits the UNREPLIED conntrack entries. If we SYN flood one
> zone, the zone will consume all entries in table, which state
> SYN_SENT.
> The openvswitch limits only the +est conntrack.

Why?  Can't it be fixed to work properly?

> > iptables -t mangle -A PREROUTING -m conntrack --ctstate NEW -m connlimit \
> >    --connlimit-above 1000 --connlimit-mask 0 -j REJECT

This should work for the synflood case, too.