From: Pascal Hambourg <pascal.mail@plouf.fr.eu.org>
To: Scott Shambarger <scott-netfilter@shambarger.net>
Cc: netfilter@vger.kernel.org
Subject: Re: Returning nat packets vanishing after mangle:PREROUTING and conntrack processing
Date: Sat, 19 Dec 2009 14:12:29 +0100 [thread overview]
Message-ID: <4B2CD13D.504@plouf.fr.eu.org> (raw)
In-Reply-To: <7ad63010a18944d3264b5ba158c236df@localhost>
Hello,
Scott Shambarger a écrit :
> I have a multi-homed server, and have been routing packets selectively
> between the public interfaces using iptables marking and iproute2 tables.
[...]
> With the setup below, bringing down either public interface results in
> normal conntrack behavior (packets are correctly nat'd back to their
> source).
It may be a source validation issue, which is common in multihomed
setups. If sysctl net.ipv4.conf.<input_interface>.rp_filter is set to 1,
does setting it to 0 fix the problem ?
[...]
> And that's where the packet dissappears... it apparently has been seen by
> conntrack, but fails to appear in the nat:PREROUTING chain.
AFAIK, only the first NEW packet of a connection appears in the nat
chains. Subsquent packets don't. If the packet does not appear in the
FORWARD nor INPUT chain, chances are it was dropped at the routing
decision stage, where source validation is performed.
next prev parent reply other threads:[~2009-12-19 13:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-18 18:23 Returning nat packets vanishing after mangle:PREROUTING and conntrack processing Scott Shambarger
2009-12-19 13:12 ` Pascal Hambourg [this message]
2009-12-19 14:37 ` Scott Shambarger
2009-12-19 18:39 ` Pascal Hambourg
2009-12-20 20:43 ` Scott Shambarger
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