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<p>Hi.</p>
<p><br>
</p>
<p>Nowadays I'm having problems to take right control of SIP messages, in a situation with user agents present in the LAN and WAN (some of them are behind NAT, to the point of view of OpenSIPS).</p>
<p>To control everything, I'm using local domain and public domain registered in the Domain table. In addiction I intend to implement the following algorithm:</p>
<p><br>
</p>
<br>
<p>If message == SIP INVITE </p>
<p>{</p>
<p><span> </span>//Tries to guess if client's request originated behind a nat. The parameter determines what heuristics is used</p>
<p><span> </span>// <span class="x_emphasis"><em>2</em></span> - the "received" test is used: address in Via is compared against source IP address of signaling .</p>
<p><span> </span>// <span class="x_emphasis"><em>32</em></span> - address in Contact is compared against source IP address of signaling.<br>
</p>
<p><span> </span>If ( ! nat_uac_test(2 + 32))</p>
<p><span> </span>{</p>
<p><span> </span><span> </span>//caller is in local network</p>
<p><br>
</p>
<p><span> </span><span> <span style="color: rgb(0, 111, 201);">If callee is behind a NAT from the point of view of opensips</span></span></p>
<p><span> </span><span> </span>{</p>
<p> avp_db_query("select domain from domain where attrs = public", "$avp(DOMAIN)");<br>
</p>
<p><span> </span><span> </span><span> </span>set_advertised_address ("$avp(DOMAIN));<br>
</p>
<p><span> </span><span> </span>}</p>
<p><span> </span><span> </span>else</p>
<p><span> </span><span> </span>{</p>
<p><span> </span><span> </span><span> avp_db_query("select domain from domain where attrs = local", "$avp(DOMAIN)");<br>
<span> </span><span> </span><span> </span>set_advertised_address ("$avp(DOMAIN));</span><br>
</p>
<p><span> </span><span> </span>}<br>
</p>
<p><span> </span>}</p>
<p><span> </span>else</p>
<p><span> </span>{</p>
<p><span> </span><span> avp_db_query("select domain from domain where attrs = public", "$avp(DOMAIN)");<br>
<span> </span><span> </span><span></span>set_advertised_address ("$avp(DOMAIN));</span><br>
</p>
<p><span> </span>}<br>
</p>
<p>}</p>
<br>
<p>However, how can I know whether the callee is not in the same network area as the caller, so the callee is behind a NAT?</p>
<p><br>
</p>
<p>Any hint will be very helpful!<br>
</p>
<p><br>
</p>
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