[Users] NAT (again)

[Klaus Darilion]

That's typical for grandstream. If a phone is behind sym NAT it should 
not use public IP:port in the message, as they are wrong. The phone 
should use private IP address to allow NAT traversal in the SIP proxy.

If you do NAT traversal for all clients, than it should not matter. But 
if you do it only for NATed clients (using the nat detection tests), 
then you might not detect that the grandstream requires NAT traversal.

regards
klaus

Mark Kent wrote:
> I'm testing my rtpproxy config with a linksys phone and a grandstream phone,
> either not NAT'ed, or behind a cisco (full cone), or behind a Netgear (symmetric).
> 
> Things generally work, but I have a problem with the grandstream
> behind the symmetric nat.
> 
> This is the register:
> 
>   U  NAT-IP:3284 -> PROXY-IP:5060
>   REGISTER sip:sip.example.com SIP/2.0
>   Via: SIP/2.0/UDP NAT-IP:3280;branch=z9hG4bK0103d0ff79cc9c02
>   From: "Grandstream" <sip:frick at sip.example.com;user=phone>;tag=743335557afcade4
>   To: <sip:frick at sip.example.com;user=phone>
>   Contact: <sip:frick at NAT-IP:3280;user=phone>
>   Authorization: Digest username="frick", realm="sip.example.com", algorithm=MD5, uri="sip:sip.example.com", nonce="foo", response="bar"
>   Call-ID: 11f6defb0857db17 at 192.168.0.100
>   CSeq: 116 REGISTER
>   Expires: 60
>   User-Agent: Grandstream BT100 1.0.6.7
>   Max-Forwards: 70
>   Allow: INVITE,ACK,CANCEL,BYE,NOTIFY,REFER,OPTIONS,INFO,SUBSCRIBE
>   Content-Length: 0
> 
> This is the resulting contact:
> 
>   ...Record(0x2864b680)..
>   domain: 'location'
>   aor   : 'frick at sip.example.com'
>   ~~~Contact(0x2864d4e0)~~~
>   domain    : 'location'
>   aor       : 'frick at sip.example.com'
>   Contact   : 'sip:frick at NAT-IP:3280;user=phone'
>   Expires   : 34
>   q         : 
>   Call-ID   : '11f6defb0857db17 at 192.168.0.100'
>   CSeq      : 119
>   User-Agent: 'Grandstream BT100 1.0.6.7'
>   received  : 'sip:NAT-IP:3284'
>   Path      : ''
>   State     : CS_SYNC
>   Flags     : 1
>   Sock      : PROXY-IP:5060 (0x8122f50)
>   Methods   : 5695
>   next      : 0x0
>   prev      : 0x0
>   ~~~/Contact~~~~
>   .../Record..
> 
> 
> Now, what I don't understand is the two ports used above: 3280 and
> 3284.  It looks like the phone thinks it is being natted to port 3280,
> but it's really getting port 3284
> 
> When I make a call I get
> 
>   U  NAT-IP:3284 -> PROXY-IP:5060
>   INVITE sip:16509415674 at sip.example.com;user=phone SIP/2.0
>   Via: SIP/2.0/UDP NAT-IP:3280;branch=z9hG4bK4a4c039fbcb5bef8
>   From: "Grandstream" <sip:frick at sip.example.com;user=phone>;tag=2dc2fc3c94e93951
>   To: <sip:16509415674 at sip.example.com;user=phone>
>   Contact: <sip:frick at NAT-IP:3280;user=phone>
>   Supported: replaces
>   Call-ID: 1f04f9c6ec474f70 at 192.168.0.100
>   CSeq: 26381 INVITE
>   User-Agent: Grandstream BT100 1.0.6.7
>   Max-Forwards: 70
>   Allow: INVITE,ACK,CANCEL,BYE,NOTIFY,REFER,OPTIONS,INFO,SUBSCRIBE
>   Content-Type: application/sdp
>   Content-Length: 419
> 
>   v=0
>   o=frick 8000 8002 IN IP4 NAT-IP
>   s=SIP Call
>   c=IN IP4 NAT-IP
>   t=0 0
>   m=audio 3295 RTP/AVP 0 8 4 18 2 15 97 9 101
>   a=sendrecv
>   a=rtpmap:0 PCMU/8000
>   a=rtpmap:8 PCMA/8000
>   a=rtpmap:4 G723/8000
>   a=rtpmap:18 G729/8000
>   a=rtpmap:2 G726-32/8000
>   a=rtpmap:15 G728/8000
>   a=rtpmap:97 iLBC/8000
>   a=fmtp:97 mode=20
>   a=rtpmap:9 G722/16000
>   a=ptime:20
>   a=rtpmap:101 telephone-event/8000
>   a=fmtp:101 0-11
> 
> and my side sends back the Proxy Authentication Required, but it sends
> it to port 3280.  Now, is that based on the Via: header or the Contact:
> header, or (unlikely) the stored contact info from the REGISTER?
> 
> The phone acts like it never got it (and I'm guessing it didn't) and
> sends the INVITE again without any auth data.
> 
> The thing that bugs me is that this is an outbound call, from the
> phone out through the NAT box, I figured that would be doable.
> 
> The Linksys942 works, so I'm hoping this is a Grandstream bug,
> or something I can fix in my openser config.
> 
> Thanks,
> -mark
> 
> _______________________________________________
> Users mailing list
> Users at openser.org
> http://openser.org/cgi-bin/mailman/listinfo/users