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

[Eric Dumazet <eric.dumazet@gmail.com>]

Le dimanche 21 novembre 2010 à 18:40 -0800, Kevin Cernekee a écrit :
> [v3:
>   Only activate the new forced_dport logic if the IP matches, but the
>   port does not. ]
> 
> 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 <cernekee@gmail.com>
> ---

Thanks for doing this work Keven !

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>