Klaus / Daniel Thanks again for assistance with this.
I've tried the solution based on add_contact_alias() and handle_ruri_alias() and it works perfectly. Richard On 22 June 2012 13:47, Klaus Darilion <klaus.mailingli...@pernau.at> wrote: > > > On 22.06.2012 13:50, Richard Brady wrote: >> >> Thanks guys, fantastic answers. >> >> You mention that NAT detection happens before save() and the flag is set >> by lookup() which makes much more sense. However, if Kamailio is not the >> registrar, as is the case with my current project, those functions are >> not called, so an alternative is needed. There are clearly several >> options. >> >> The solution I have gone for is to replace fix_nated_register() with >> fix_nated_contact() so that the REGISTER request is relayed with a >> modified Contact header containing the external ip:port of the client. > > > The cleanest solution would be to use add_contact_alias() and > handle_ruri_alias(). The do not change the contact but put the public > address into a uri parameter. Thus, the URI seen by the client is always the > one it sends: > http://www.kamailio.org/docs/modules/3.2.x/modules_k/nathelper.html#id2550431 > > >> That is then stored by the registrar (FreeSWITCH in my case) and used >> later to originate calls for that user. The FreeSWITCH know to send >> those calls to Kamailio through either use of the Path header and module >> in Kamailio, or through static configuration of fs_path or proxy >> parameters in FreeSWITCH. > > > This is fine. > > >> The works for the first INVITE to the registered client behind NAT. But >> that client sends back a 200 OK with a Contact header containing its >> private IP address, and so fix_nated_contact() needs to be invoked on >> that response, and normally it would be due to FLB_NATB being set, but >> if Kamailio was not the registrar then that flag is not set. So I need >> to detect NAT on the client at the time of receiving the reply, or >> alternatively by having the registrar store a cookie and setting it >> based on that. > > > You are correct. For in-dialog messages received from SIP clients I would > always use add_contact_alias() and remove the NAT flags completely. > >> >> I suppose then my next question then is can I call nat_uac_test() on a >> UAS? > > > Today, almost any SIP clients are SIP symmetric. This means, that they > receive SIP from the some port/connection where they send. Thus, skip the > NAT tests completely and always use add_contact_alias() for messages receive > from SIP clients and handle_ruri_alias() for messages sent to SIP clients. > > Depending on if you use Freeswitch also as media relay you can also remove > the media proxy stuff from the Kamailio config. > > On important thing is NAT-keep-alive. This is usually done by nathelper > module by querying the location table for contact with NAT-flag set. Thus, > either you do NAT keep-alive by freeswitch (e.g sending OPTIONS requests) or > do it in your Kamailio proxy (e.g. set the nat_bflag > http://www.kamailio.org/docs/modules/3.2.x/modules_k/usrloc.html#id2541477 > and call save("location","0x02") before relaying REGISTER to freeswitch. > Then Kamailio will do NAT-pinging. Note, if you want to keep-alive only for > successfully registered clients, you man want to call save() in the > reply-route of the REGISTER request). > > regards > Klaus _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users