[Serusers] Responses on the source port of the request

[Marian Dumitru]

Hi Mahesh,

force_rport() is used as a part of the NAT traversal solution. When a 
request come across a NAT, the server will see a different port (the one 
of the NAT), instead of the one advertise in VIA. And to be able to pass 
the reply back to UAC (through NAT), the server MUST use the detected 
NAT port (otherwise the NAT will not allow the message to pass).

best regards,
Marian

mahesh wrote:

> Andrei,
>
> Any significant reason on why this is being done??
>
> Mahesh
>
> At 08:59 PM 10/1/2004, Andrei Pelinescu-Onciul wrote:
>
>> On Oct 01, 2004 at 10:16, mahesh <mahesha at intoto.com> wrote:
>> > Hi Andrei,
>> > Thanks for the reply.
>> >
>> > I am using the publicly available iptel proxy server(195.37.77.99) 
>> to test
>> > my implementation of SIP-ALG. I am using the following configuration
>> >
>> > HOST1(winXP)---FW---Internet---HOST2(winCP)
>> >
>> > FW is the firewall/NAT device, which has the ALG implementation. I 
>> am using
>> > SJPhone on my hosts to communicate using SIP(UDP). I observe that the
>> > responses to requests sent by HOST1 come from the proxy(iptel) to the
>> > source port(of FW), from which the request was sent, instead of on 
>> VIA.
>> > There is no "rport"  field in the VIA header field of the request.
>> >
>> > Does anyone know if the iptel proxy server is configured to use
>> > "force_rport".
>>
>> Yes, it is.
>>
>> Andrei
>
>
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