nat_uac_test question - sr-users

9 Jul 2015

Hello,

  I'm testing some basic flags with nat_uac_test. I have the following
(rudimentary) script:

route[NATDETECT] {
#!ifdef WITH_NAT
        if (has_body("application/sdp")) {
                if (nat_uac_test("18")) {
                        xlog("SCRIPT: SDP NAT Detected\n");
                        setflag(6);
                }
        } else {
                if (nat_uac_test("2")) {
                        xlog("SCRIPT: Other NAT Detected\n");
                        setflag(6);
                }
        }

        if (isflagset(6)) {
                xlog("SCRIPT: NAT detected\n");
                force_rport();
                if (is_method("REGISTER")) {
                        fix_nated_register();
                } else {
                        if(is_first_hop())
                                set_contact_alias();
                }
                setflag(FLT_NATS);
        }
#!endif
        return;
}

  When presented with this REGISTER message (ngrep output, so first
line is IP source address and port):

U 192.168.113.17:6060 -> 192.168.113.11:5060
REGISTER sip:192.168.113.11;transport=udp SIP/2.0.
Via: SIP/2.0/UDP 192.168.113.17:6060;branch=z9hG4bKOzvuzaIa;rport.
From: <sip:user_1@192.168.113.11>;tag=3F785909-559E7E9F0009321B-B5BFFB40.
To: <sip:user_1@192.168.113.11>.
CSeq: 10 REGISTER.
Call-ID: 1C193C6B-559E7E9F00093255-B5BFFB40.
Max-Forwards: 70.
User-Agent: FreeSWITCH.
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE,
REGISTER, REFER, NOTIFY.
Supported: timer, path, replaces.
Contact: <sip:gw+sip0@10.40.47.190:5080;transport=udp;gw=sip0>;expires=3600.
Content-Length: 0.
.

U 192.168.113.11:5060 -> 192.168.113.17:6060
SIP/2.0 200 OK.
Via: SIP/2.0/UDP
192.168.113.17:6060;branch=z9hG4bKOzvuzaIa;rport=6060;received=192.168.113.17.
From: <sip:user_1@192.168.113.11>;tag=3F785909-559E7E9F0009321B-B5BFFB40.
To: <sip:user_1@192.168.113.11>;tag=b27e1a1d33761e85846fc98f5f3a7e58.1045.
CSeq: 10 REGISTER.
Call-ID: 1C193C6B-559E7E9F00093255-B5BFFB40.
Contact:
<sip:gw+sip0@10.40.47.190:5080;transport=udp;gw=sip0>;expires=3600;received="sip:192.168.113.17:6060".
Server: Kamailio.
Content-Length: 0.
.

Log output:

Jul  9 10:00:41 kamailio /usr/sbin/kamailio[3886]: ERROR: <script>:
SCRIPT: Other NAT Detected
Jul  9 10:00:41 kamailio /usr/sbin/kamailio[3886]: ERROR: <script>:
SCRIPT: NAT detected

  Log output, the presence of the added "received" parameter in the
returned Contact, etc show that NAT was detected. However, the IP
source and port match the one presented in the Via header.

  What am I missing here?

Thanks!

-- 
Kristian Kielhofner