From: Jan Engelhardt <jengelh@inai.de>
To: Wouter <wouter-netfilter@publica.duodecim.org>
Cc: netfilter@vger.kernel.org
Subject: Re: module order: tcp/conntrack vs. conntrack/tcp
Date: Mon, 2 Jul 2012 14:16:10 +0200 (CEST) [thread overview]
Message-ID: <alpine.LNX.2.01.1207021414160.9210@frira.zrqbmnf.qr> (raw)
In-Reply-To: <9bfb14742a7ec35d775699fc955f437b@localhost>
On Monday 2012-07-02 14:02, Wouter wrote:
>I'm wondering about the practical difference between these seemingly
>equivalent rules (notice the module order):
>
>iptables -A INPUT -i eth0 -p tcp --dport 8140 -m state --state NEW -j
>ACCEPT
>iptables -A INPUT -i eth0 -p tcp -m state --state NEW -m tcp --dport 8140
>-j ACCEPT
>
>While I always use the form of rule 1 (filter first, then state NEW), I
>found some systems configured like rule 2 – which appears to have the same
>end result – and I wonder if rule 2 (state first, then filter) has any side
>effects or causes more overhead.
The use of -m conntrack (state is obsolete) is cheaper than people
think, because the ct belonging to a packet is already long determined,
so looking at the state is quite simple.
next prev parent reply other threads:[~2012-07-02 12:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-02 12:02 module order: tcp/conntrack vs. conntrack/tcp Wouter
2012-07-02 12:16 ` Jan Engelhardt [this message]
2012-07-02 12:49 ` Wouter
2012-07-03 1:57 ` Julien Vehent
2012-07-03 11:56 ` Jan Engelhardt
2012-07-04 5:47 ` Julien Vehent
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