From: Patrick McHardy <kaber@trash.net>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: Netfilter Developer Mailing List
<netfilter-devel@vger.kernel.org>,
Netfilter Core Team <coreteam@netfilter.org>
Subject: Re: [RFC PATCH] netfilter: nf_nat: support user-specified SNAT rules in LOCAL_IN
Date: Thu, 17 Jun 2010 09:44:23 +0200 [thread overview]
Message-ID: <4C19D257.5090101@trash.net> (raw)
In-Reply-To: <alpine.LSU.2.01.1006170924040.12057@obet.zrqbmnf.qr>
Jan Engelhardt wrote:
> On Wednesday 2010-06-16 17:09, Patrick McHardy wrote:
>
>>
>> This works well, but is needlessly complicated for cases where only
>> a single SNAT/DNAT mapping needs to be applied to these packets. In that
>> case, all that needs to be done is to assign each network to a seperate
>> zone and perform NAT as usual. However this doesn't work for packets
>> destined for the machine performing NAT itself since its corrently not
>> possible to configure SNAT mappings for the LOCAL_IN chain.
>>
>> Example usage with two identical networks (192.168.0.0/24) on eth0/eth1:
>>
>> # assign packets from each interface to a seperate zone and mark them for NAT
>>
>> iptables -t raw -A PREROUTING -i eth0 -j CT --zone 1
>> iptables -t raw -A PREROUTING -i eth0 -j MARK --set-mark 1
>> iptables -t raw -A PREROUTING -i eth1 -j CT --zone 2
>> iptabels -t raw -A PREROUTING -i eth1 -j MARK --set-mark 2
>>
>> # SNAT packets to private networks: eth0 -> 10.0.0.0/24, eth1 -> 10.0.1.0/24
>>
>> iptables -t nat -A INPUT -m mark --mark 1 -j NETMAP --to 10.0.0.0/24
>> iptables -t nat -A POSTROUTING -m mark --mark 1 -j NETMAP --to 10.0.0.0/24
>> iptables -t nat -A INPUT -m mark --mark 2 -j NETMAP --to 10.0.1.0/24
>> iptables -t nat -A POSTROUTING -m mark --mark 2 -j NETMAP --to 10.0.1.0/24
>>
>
> I am not sure I follow whatever this is supposed to do.
>
> Packet from eth0: src=10.0.0.15 dst=10.0.1.22
> INPUT#NETMAP will dst transform that to dst=10.0.0.22
nat/INPUT performs source NAT, not destination NAT.
> POSTROUTING#NETMAP will src transform that to src=10.0.0.15
>
> Is is this step that makes no sense to me.
Does it make sense now?
next prev parent reply other threads:[~2010-06-17 7:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-16 15:09 [RFC PATCH] netfilter: nf_nat: support user-specified SNAT rules in LOCAL_IN Patrick McHardy
2010-06-17 7:28 ` Jan Engelhardt
2010-06-17 7:44 ` Patrick McHardy [this message]
2010-06-17 7:52 ` Jan Engelhardt
2010-06-17 7:55 ` Patrick McHardy
2010-06-17 8:58 ` Jan Engelhardt
2010-06-17 15:22 ` Patrick McHardy
2010-06-20 8:31 ` Jan Engelhardt
2010-06-22 7:20 ` Patrick McHardy
2010-06-28 14:40 ` Jan Engelhardt
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