Subject: Re: [PATCH v3 resend] netfilter: nf_conntrack_sip: Handle Cisco 7941/7945 IP phones

From: Pablo Neira Ayuso <[email-masked]>
Date: Thu, 26 May 2011 18:50:58 +0200

Hi Eric,

On 20/05/11 06:36, 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.
> 
> Signed-off-by: Kevin Cernekee <[email-masked]>
> Acked-by: Eric Dumazet <[email-masked]>
> Cc: Patrick McHardy <[email-masked]>

@Eric: could you please confirm that you ack'ed this patch? I don't find
the email with your explicit ack.