From: Florian Westphal <fw@strlen.de>
To: Aaron Fischer <mail@aaron-fischer.net>
Cc: netfilter@vger.kernel.org
Subject: Re: nftables: origin sport after dstnat
Date: Wed, 7 Dec 2022 12:29:00 +0100 [thread overview]
Message-ID: <20221207112900.GA28507@breakpoint.cc> (raw)
In-Reply-To: <20221206230347.205a59c1@deskFu>
Aaron Fischer <mail@aaron-fischer.net> wrote:
> The problem is that the DOCKER-USER chain is behind the dnat, so I
> can't use "sport", because it is already a random port from the dnat :(
>
> With a trace in that chain, I got this (sport is 57484, a random port)
> and the filter rule does not work.
>
> trace id 2a3fb2fd ip filter DOCKER-USER packet: iif "eth0" oif "docker0" ether saddr 52:54:00:8e:37:c7 ether daddr 52:54:00:9c:e5:b7 ip saddr 192.168.122.1 ip daddr 172.17.0.2 ip dscp cs0 ip ecn not-ect ip ttl 63 ip id 57921 ip length 60 tcp sport 57484 tcp dport 5000 tcp flags == syn tcp window 64240
> trace id 2a3fb2fd ip filter DOCKER-USER rule tcp sport != 8448
> counter packets 6 bytes 360 drop (verdict drop)
>
> Is there a way to somehow access the origin sport (8448 in my case), so
> I can filter for it in the FORWARD chain?
Yes, the original addresses are stored in conntrack: 'ct original proto-src 8448'
next prev parent reply other threads:[~2022-12-07 11:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-06 22:03 nftables: origin sport after dstnat Aaron Fischer
2022-12-07 11:29 ` Florian Westphal [this message]
2022-12-07 23:31 ` Aaron Fischer
2022-12-08 7:48 ` Florian Westphal
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