[SR-Users] rport parameter in VIA header in uac remote registration

Daniel-Constantin Mierla miconda at gmail.com
Thu Nov 12 09:36:50 CET 2020

I pushed a commit to master branch trying to catch the use of
add_local_rport() in the event route and trigger a rebuild of via. If
you have time to test with master branch, let us know if works or not.

Your solution is ok as well.


On 11.11.20 21:28, Jetse Verschuren wrote:
> Thanks for your quick response,
> Unfortunately add_local_rport() didn't work, but
> event_route[tm:loal-request] did work. In the end I manually changed
> the header (see below), not the prettiest solution, but it works.
> event_route [tm:local-request] {
>         xlog("L_INFO", "Routing locally generated $rm to $ru\n");
>         if (is_method("REGISTER")) {
>                 xlog("L_INFO", "Adding rhost parameter to REGISTER
> request\n");
>                 # Add rport parameter to Via header
>                 assign_hf_value("Via", "$hdr(Via);rport");
>         }
> }
> Thanks again,
> Jetse
> On Wed, Nov 11, 2020 at 9:42 AM Daniel-Constantin Mierla
> <miconda at gmail.com <mailto:miconda at gmail.com>> wrote:
>     Hello,
>     try to catch uac registrations requests inside
>     event_route[tm:local-requests] and use add_local_rport() for them
>     -- not sure it works because I haven't tracked in the code, given
>     that add_local_rport() was intended for forwarding incoming
>     requests, but it is a chance it does.
>     Cheers,
>     Daniel
>     On 11.11.20 08:38, Jetse Verschuren wrote:
>>     Hi,
>>     I'm currently trying to connect Kamailio, running in docker, to
>>     my FritzBox. The FritzBox is the modem provided by my ISP, with a
>>     builtin voip server which I can use to dial out (basically a PSTN
>>     gateway). In my setup I have a custom router/firewall/NAT between
>>     the FritzBox and the server.
>>     When I connect LinPhone to the FritzBox, from behind the NAT, it
>>     works fine. But when I use the Kamailio uac remote registration, 
>>     I don't get a response. After some investigation with wireshark,
>>     I found that the the SIP response from the FritzBox comes on the
>>     wrong port, and gets rejected by the NAT. The request comes from
>>     port 1025, but the response is sent to port 5060. I compared the
>>     requests from LinPhone and Kamailio, and combined with some
>>     research, found it probably was the rport option in the VIA
>>     header. From what I read, it basically signals the uas to use the
>>     source port to reply to, instead of the port indicated in the
>>     request, which would be necessary to effectively go through a NAT.
>>     After reading a lot of documentation (and even parts of the
>>     source), I wasn't able to find an option to enable this option.
>>     Is there some option I completely missed, or is it not possible?
>>     Or am I completely wrong in my "diagnosis"?
>>     Thanks in advance,
>>     Jetse
>>     _______________________________________________
>>     Kamailio (SER) - Users Mailing List
>>     sr-users at lists.kamailio.org <mailto:sr-users at lists.kamailio.org>
>>     https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users <https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users>
>     -- 
>     Daniel-Constantin Mierla -- www.asipto.com <http://www.asipto.com>
>     www.twitter.com/miconda <http://www.twitter.com/miconda> -- www.linkedin.com/in/miconda <http://www.linkedin.com/in/miconda>
>     Funding: https://www.paypal.me/dcmierla <https://www.paypal.me/dcmierla>
Daniel-Constantin Mierla -- www.asipto.com
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Funding: https://www.paypal.me/dcmierla

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