[OpenSIPS-Users] Issues with RURI port VS contact port when ACK is relayed back to UA

[Bogdan-Andrei Iancu]

Hi Bobby,

what you could do is to store into "fixed" contact the original IP and 
port, so that you can restore he original contact in sequential requests.

like you received sip:foo at ip_1:port_1 -> fixing to 
sip:foo at ip_2:port_2;xip=ip_1;xport=ip_1
See: 
http://www.opensips.org/html/docs/modules/1.7.x/nathelper.html#id250346  
(take a look at params)

and when you receive an RURI like 
sip:foo at ip_2:port_2;xip=ip_1;xport=ip_1 you move current IP and port 
into DURI and upload xip and xport into URI.

Regards,
Bogdan

On 08/19/2011 07:28 AM, Bobby Smith wrote:
> All,
>
> Setup is this:
>
> Softswitch --> OpenSIPS Proxy/Registrar --> UAC
>
> INVITE sip:username at uac_ip:port is sent to uac via lookup on the 
> location table:
>
> ---> INVITE sip:user at foo.com:5063 <http://sip:user@foo.com:5063> (but 
> destination port from UA's contact is really 7063).
> R-R us
> Contact: <sip:did at softswitchip:port>
>
> <--------  200 OK
> via them
> Contact: <sip:user at foo.com:5063 <http://sip:user@foo.com:5063>>, which 
> is rewritten to sip:user at foh.com:7063 <http://sip:user@foh.com:7063> 
> because of fix_nated_contact called
>
>
> -----------> ACK sip:user at bar.com:7063 <http://sip:user@bar.com:7063> 
> (sent to ua at 7063).
>               R-R us
>
> The problem is the UAC tosses out the request because it doesn't match 
> it as the RURI port is wrong, even though it was sent to the right place.
>
> My question is:
>
> If I call loose route on this without fixing up the IP, it would be 
> relayed to the private_ip:port pair of the UA.
> If I do another lookup, the RURI is preserved with the port 7063 but 
> sent to the right place (in this case 7063, but the request is thrown 
> out).
>
> What I want to achieve is on the ACK:
>
> duri = sip:user at bar.com:5073 <http://sip:user@bar.com:5073>
> ruri = sip:user at foo.com:5063 <http://sip:user@foo.com:5063>
>
>
> The initial INVITE packet has the correct duri/ruri combo, but because 
> I call fix_nated_contact, the softswitch rewrites the RURI (as it's 
> supposed to) with the Contact Header info, and opensips relays this 
> back to the UAC with that information.
>
> Is there a simple convention to set the duri to be the correct 
> destination via lr or via doing another location lookup (hackish I 
> guess, but even this doesn't work for me), while preserving the RURI 
> on the initial invite?  If i don't rewrite the contact header, the 
> packet is relayed back to the private IP and seems to break NAT.
>
> If I do another user lookup, the ruri is rewritten.  This is a phone 
> that doesn't exactly support RFC 3261 (a Cisco 79XX with SIP 8.0 
> firmware), and doesn't support received processing.
>
>
> Thanks,
> BobbyS
>
>
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-- 
Bogdan-Andrei Iancu
OpenSIPS eBootcamp - 19th of September 2011
OpenSIPS solutions and "know-how"

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