[Users] UA behind NAT puts public IP in Contact, Via - help

Fri Mar 17 10:09:42 CET 2006

Hi Arek,

looking on the signalling, you cannot detect the call as nated from 
proxy point of view, so there is not much you can do. It's a typically 
situation where the the phones tries to perform nat traversal on its 
sides but does not do a complete job, preventing also the proxy to do it :(

regards,
bogdan

Arek Bekiersz wrote:

> Hi Bogdan,
>
>
>
>
> Bogdan-Andrei Iancu wrote:
>
>> as the trace shows, the phone does via SIP a kind of auto-detection 
>> of the external IP based on received and rport via params.... can you 
>> disable this feature?
>
>
> You are right.
>
> No, I cannot disable it. There is no such option :-(((
> I send you the trace of INVITE transaction as seen from LAN behind 
> NAT. It shows that also SDP is rewritten.
>
>
>
>------------------------------------------------------------------------
>
>---------------------------------------------------------------------------
>Packet 1
>Source IP Address:192.168.1.200 
>Destination IP Address:proxy_public_ip 
>
>INVITE sip:1234 at proxy_realm SIP/2.0.
>Via: SIP/2.0/udp nat_public_ip:61001;branch=z9hG4bK483828829A0FFE1CBE2D351EC40C9.
>From: <sip:5678 at proxy_realm>;tag=A37DA72FCC637B1D7AEB5AEAFEBC2.
>To: <sip:1234 at proxy_realm>.
>Call-ID: 4B7150B7D8D94964AE0470E367DE9 at nat_public_ip.
>CSeq: 5 INVITE.
>Contact: <sip:5678 at nat_public_ip:61001;uniq=0FC6DA2B97704905AA040333C2B03>.
>Max-Forwards: 70.
>Expires: 120.
>User-Agent: trouble-user-agent
>.
>Supported: 100rel, replaces.
>Allow-Events: telephone-event, refer.
>Allow: INVITE, ACK, OPTIONS, CANCEL, BYE, UPDATE, PRACK, INF
>O, SUBSCRIBE, NOTIFY, REFER, MESSAGE.
>Content-Type: application/sdp.
>Accept: application/sdp, multipart/mixed.
>Accept-Encoding: identity.
>Content-Length:   277.
>.
>v=0.
>o=user 6744156 6744156 IN IP4 nat_public_ip.
>s=call.
>c=IN IP4 nat_public_ip.
>t=1140702179 1140705779.
>m=audio 7078 RTP/AVP 2 102 18 8 101.
>a=sendrecv.
>a=rtpmap:2 G726-32/8000.
>a=rtpmap:102 G726-32/8000.
>a=rtpmap:101 telephone-event/8000.
>a=fmtp:101 0-11.
>a=rtcp:7079.
>
>
>---------------------------------------------------------------------------
>Packet 2
>
>Source IP Address:proxy_public_ip 
>Destination IP Address:192.168.1.200 
>
>SIP/2.0 407 Proxy Authentication Required.
>Via: SIP/2.0/udp nat_public_ip:61001;branch=z9hG4bK483828829A0FFE1CBE2D351EC40C9.
>From: <sip:5678 at proxy_realm>;tag=A37DA72FCC637B1D7AEB5AEAFEBC2.
>To: <sip:1234 at proxy_realm>;tag=935ab969d5b642f019e17a3a52b4e4b2.341c.
>Call-ID: 4B7150B7D8D94964AE0470E367DE9 at nat_public_ip.
>CSeq: 5 INVITE.
>Proxy-Authenticate: Digest realm=".....
>Server: Sip EXpress router.
>Content-Length: 0.
>.
>
>
>---------------------------------------------------------------------------
>Packet 3
>Source IP Address:192.168.1.200 
>Destination IP Address:proxy_public_ip 
>
>ACK sip:1234 at proxy_realm SIP/2.0.
>Via: SIP/2.0/udp nat_public_ip:61001;branch=z9hG4bK483828829A0FFE1CBE2D351EC40C9.
>From: <sip:5678 at proxy_realm>;tag=A37DA72FCC637B1D7AEB5AEAFEBC2.
>To: <sip:1234 at proxy_realm>;tag=935ab969d5b642f019e17a3a52b4e4b2.341c.
>Call-ID: 4B7150B7D8D94964AE0470E367DE9 at nat_public_ip.
>CSeq: 5 ACK.
>User-Agent: trouble-user-agent
>.
>Content-Length: 0.
>.
>
>
>---------------------------------------------------------------------------
>Packet 4
>Source IP Address:192.168.1.200 
>Destination IP Address:proxy_public_ip 
>
>INVITE sip:1234 at proxy_realm SIP/2.0.
>Via: SIP/2.0/udp nat_public_ip:61001;branch=z9hG4bK0DA7F19CA20D7B6DA35154CA9467C.
>From: <sip:5678 at proxy_realm>;tag=A37DA72FCC637B1D7AEB5AEAFEBC2.
>To: <sip:1234 at proxy_realm>.
>Call-ID: 4B7150B7D8D94964AE0470E367DE9 at nat_public_ip.
>CSeq: 6 INVITE.
>Contact: <sip:5678 at nat_public_ip:61001;uniq=0FC6DA2B977049
>05AA040333C2B03>.
>Proxy-Authorization: Digest username="5678", realm=".....
>Max-Forwards: 70.
>Expires: 120.
>User-Agent: trouble-user-agent
>.
>Supported: 100rel, replaces.
>Allow-Events: telephone-event, refer.
>Allow: INVITE, ACK, OPTIONS, CANCEL, BYE, UPDATE, PRACK, INF
>O, SUBSCRIBE, NOTIFY, REFER, MESSAGE.
>Content-Type: application/sdp.
>Accept: application/sdp, multipart/mixed.
>Accept-Encoding: identity.
>Content-Length:   277.
>.
>v=0.
>o=user 6744156 6744156 IN IP4 nat_public_ip.
>s=call.
>c=IN IP4 nat_public_ip.
>t=1140702179 1140705779.
>m=audio 7078 RTP/AVP 2 102 18 8 101.
>a=sendrecv.
>a=rtpmap:2 G726-32/8000.
>a=rtpmap:102 G726-32/8000.
>a=rtpmap:101 telephone-event/8000.
>a=fmtp:101 0-11.
>a=rtcp:7079.
>
>
>---------------------------------------------------------------------------
>Packet 5
>Source IP Address:proxy_public_ip 
>Destination IP Address:192.168.1.200 
>
>SIP/2.0 100 trying -- your call is important to us.
>Via: SIP/2.0/udp nat_public_ip:61001;branch=z9hG4bK0DA7F19CA20D7B6DA35154CA9467C.
>From: <sip:5678 at proxy_realm>;tag=A37DA72FCC637B1D7AEB5AEAFEBC2.
>To: <sip:1234 at proxy_realm>.
>Call-ID: 4B7150B7D8D94964AE0470E367DE9 at nat_public_ip.
>CSeq: 6 INVITE.
>Server: Sip EXpress router.
>Content-Length: 0.
>.
>
>
>---------------------------------------------------------------------------
>Packet 6
>Source IP Address:proxy_public_ip 
>Destination IP Address:192.168.1.200 
>
>SIP/2.0 180 Ringing.
>Via: SIP/2.0/udp nat_public_ip:61001;branch=z9hG4bK0DA7F19CA20D7B6DA35154CA9467C.
>From: <sip:5678 at proxy_realm>;tag=A37DA72FCC637B1D7AEB5AEAFEBC2.
>To: <sip:1234 at proxy_realm>;tag=as490a0c26.
>Call-ID: 4B7150B7D8D94964AE0470E367DE9 at nat_public_ip.
>CSeq: 6 INVITE.
>User-Agent: good-ua
>Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER.
>Contact: <sip:1234 at good-ua-ip>.
>Content-Length: 0.
>.
>
>
>---------------------------------------------------------------------------
>Packet 8
>Source IP Address:proxy_public_ip 
>Destination IP Address:192.168.1.200 
>
>SIP/2.0 200 OK.
>Via: SIP/2.0/udp nat_public_ip:61001;branch=z9hG4bK0DA7F19CA20D7B6DA35154CA9467C.
>Record-Route: <sip:1234 at proxy_public_ip;ftag=A37DA72FCC637B1D7AEB5AEAFEBC2;lr=on>.
>From: <sip:5678 at proxy_realm>;tag=A37DA72FCC637B1D7AEB5AEAFEBC2.
>To: <sip:1234 at proxy_realm>;tag=as490a0c26.
>Call-ID: 4B7150B7D8D94964AE0470E367DE9 at nat_public_ip.
>CSeq: 6 INVITE.
>User-Agent: good-ua
>Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER.
>Contact: <sip:1234 at good-ua-ip>.
>Content-Type: application/sdp.
>Content-Length: 297.
>.
>v=0.
>o=root 10049 10049 IN IP4 good-ua-ip.
>s=session.
>c=IN IP4 good-ua-ip.
>t=0 0.
>m=audio 10276 RTP/AVP 2 5 8 0 101.
>a=rtpmap:2 G726-32/8000.
>a=rtpmap:5 DVI4/8000.
>a=rtpmap:8 PCMA/8000.
>a=rtpmap:0 PCMU/8000.
>a=rtpmap:101 telephone-event/8000.
>a=fmtp:101 0-16.
>a=silenceSupp:off - - - -.
>
>
>---------------------------------------------------------------------------
>Packet 9
>Source IP Address:192.168.1.200 
>Destination IP Address:proxy_public_ip 
>
>ACK sip:1234 at 194.183.228.175 SIP/2.0.
>Via: SIP/2.0/UDP nat_public_ip:61001;branch=z9hG4bK4E416AB44C125E935C1A974F2EA86.
>Route: <sip:1234 at proxy_public_ip;ftag=A37DA72FCC637B1D7AEB5AEAFEBC2;lr=on>.
>From: <sip:5678 at proxy_realm>;tag=A37DA72FCC637B1D7AEB5AEAFEBC2.
>To: <sip:1234 at proxy_realm>;tag=as490a0c26.
>Call-ID: 4B7150B7D8D94964AE0470E367DE9 at nat_public_ip.
>CSeq: 6 ACK.
>Contact: <sip:5678 at nat_public_ip:61001;uniq=0FC6DA2B97704905AA040333C2B03>.
>Max-Forwards: 70.
>User-Agent: trouble-user-agent
>.
>Content-Length: 0.
>  
>