Hello,<br><br>you can do nat_uac_test() for reply and it will detect is it natted, then you can call fix_nated_contact() -- this being another option.<br><br>Cheers,<br>Daniel<br><br><div class="gmail_quote">On Fri, Mar 9, 2012 at 8:56 PM, Giacomo Vacca <span dir="ltr"><<a href="mailto:Giacomo.Vacca@truphone.com">Giacomo.Vacca@truphone.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div link="blue" vlink="purple" lang="EN-GB">
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<p class="MsoNormal">Hi all,</p>
<p class="MsoNormal">I have a scenario where it’s not clear to me what the best approach should be (Kamailio 3.2.0 on Squeeze, although I think it’s a matter of routing logic only).</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I have a client behind NAT that sends an initial REGISTER request with a Contact containing private ip:port (e.g.
</p>
<p class="MsoNormal">Contact: “GV” <<a>sip:12345@192.168.1.2:54321;transport=tcp</a>></p>
<p class="MsoNormal">)</p>
<p class="MsoNormal">However, after it’s challenged for authentication with a 401, it sends the following REGISTER request with Authorization header and with a Contact containing ip:port equal to the ‘received’ SIP URI (with a combination of ‘rport’ and ‘received’
parameters (e.g.</p>
<p class="MsoNormal">Contact: “GV” <<a>sip:12345@[received</a>IP]:[rport];transport=tcp></p>
<p class="MsoNormal">)</p>
<p class="MsoNormal">In this case kamailio’s routing logic is not marking the REGISTER as natted (no Received field in location and no NAT flags set).</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">You can imagine I have a fairly standard NAT handling:</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">route[NATDETECT] {</p>
<p class="MsoNormal"> force_rport();</p>
<p class="MsoNormal"> if (nat_uac_test("19")) {</p>
<p class="MsoNormal"> if (is_method("REGISTER")) {</p>
<p class="MsoNormal"> fix_nated_register();</p>
<p class="MsoNormal"> } else {</p>
<p class="MsoNormal"> fix_nated_contact();</p>
<p class="MsoNormal"> }</p>
<p class="MsoNormal"> setflag(FLT_NATS);</p>
<p class="MsoNormal"> }</p>
<p class="MsoNormal"> return;</p>
<p class="MsoNormal">}</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">FLT_NATS won’t be set, and so it won’t FLB_NATB in the following processing.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">This client receives a call: Kamailio relays the INVITE to it using the stored Contact. The INVITE is correctly received by the client, because the stored Contact refers to the connected socket ([received]:rport).</p>
<p class="MsoNormal">The trouble starts when then the client replies with a 200 OK containing the private ip:port in the Contact header field (again <a href="http://192.168.1.2:54321" target="_blank">192.168.1.2:54321</a>).</p>
<p class="MsoNormal">The ACK will then have that private ip:port in the R-URI, and its relaying will fail.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">One of the solutions I’ve found is using <i>always </i>add_contact_alias() in onreply_route when handling the 200 OK, and then use handle_ruri_alias() when defining the destination for the ACK.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I know that without traces and the full .cfg this is quite a broad question, but I wonder if you have already had to deal with this kind of client behaviour and can provide advice on the best practices.</p>
<p class="MsoNormal">This is in particular useful for the re-use of TCP-based connections.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Thanks in advance,</p>
<p class="MsoNormal">Giacomo</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> </p>
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