From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pablo Neira Ayuso <pablo@netfilter.org>
Subject: Re: [PATCH v4] netfilter: nf_conntrack_sip: Handle Cisco 7941/7945
 IP phones
Date: Fri, 18 Jan 2013 00:35:39 +0100
Message-ID: <20130117233539.GA15576@1984>
References: <1355805238-2460-1-git-send-email-cernekee@gmail.com>
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Cc: David Woodhouse <dwmw2@infradead.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Patrick McHardy <kaber@trash.net>,
	"David S. Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	"Pekka Savola (ipv6)" <pekkas@netcore.fi>,
	James Morris <jmorris@namei.org>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Gabor Juhos <juhosg@openwrt.org>,
	netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org,
	coreteam@netfilter.org, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org
To: Kevin Cernekee <cernekee@gmail.com>
Return-path: <netfilter-owner@vger.kernel.org>
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In-Reply-To: <1355805238-2460-1-git-send-email-cernekee@gmail.com>
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On Mon, Dec 17, 2012 at 08:33:58PM -0800, Kevin Cernekee wrote:
> Most SIP devices use a source port of 5060/udp on SIP requests, so the
> response automatically comes back to port 5060:
> 
>     phone_ip:5060 -> proxy_ip:5060   REGISTER
>     proxy_ip:5060 -> phone_ip:5060   100 Trying
> 
> The newer Cisco IP phones, however, use a randomly chosen high source
> port for the SIP request but expect the response on port 5060:
> 
>     phone_ip:49173 -> proxy_ip:5060  REGISTER
>     proxy_ip:5060 -> phone_ip:5060   100 Trying
> 
> Standard Linux NAT, with or without nf_nat_sip, will send the reply back
> to port 49173, not 5060:
> 
>     phone_ip:49173 -> proxy_ip:5060  REGISTER
>     proxy_ip:5060 -> phone_ip:49173  100 Trying
> 
> But the phone is not listening on 49173, so it will never see the reply.
> 
> This patch modifies nf_*_sip to work around this quirk by extracting
> the SIP response port from the Via: header, iff the source IP in the
> packet header matches the source IP in the SIP request.

Applied, thanks Kevin.