[OpenSIPS-Users] rPort question

Bogdan-Andrei Iancu bogdan at opensips.org
Fri Jul 8 18:34:26 CEST 2011


Hi José,

'rport' VIA param is to be used in NAT situations. As the VIA hdr is 
used for routing back the replies, if the caller is behind nat (and its 
VIA with a private IP), the routing back of the reply to it will not be 
possible.

The way rport works it is very simple - this param (together with 
"received") are added to the top most VIA hdr if this VIA indicates a 
different IP:port than the src ip:port on net level. The received and 
rport are added to contain the layer 3 IP and port (which can be used 
later for routing back the reply).

Regards,
Bogdan

On 07/06/2011 01:55 AM, José Pablo Méndez Soto wrote:
> Hello,
>
> Can anybody explain how the rPort works in conjunction with STUN?
>
> I have gone through the RFCs but can't make sense out of  a packet 
> capture I have over here. If possible, I would like someone to explain 
> how the layer 3 and 5 IP addresses will flow and be re-writed when SIP 
> works behind a NAT (Just one side behind NAT  and the other publicly 
> available lets say).
>
> Thanks in advance,

-- 
Bogdan-Andrei Iancu
OpenSIPS eBootcamp - 2nd of May 2011
OpenSIPS solutions and "know-how"




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