[SR-Users] Kamailio behind NAT - Wrong VIA Header

[Marko Seidenglanz]

Hello,

We are using Kamailio 4.2 and RTPEngine 3.3  hosted on a VM behind NAT in
Google Cloud Engine.

Asterisk 11 + Kamailio + RTPEngine are on the same machine and Kamailio is
used as WebRTC Gateway.

INVITES, that are rewritten by Kamailio look like the following:

INVITE sip:eTden7KoNSdMVCUNYIwmz at wh2.24dial.com SIP/2.0
Record-Route: <sip:0.0.0.0:5064;lr=on;nat=yes>
Via: SIP/2.0/UDP 0.0.0.0:5064
;branch=z9hG4bK86f5.88fb7f8810c91758b5f3962420d3a4ef.0
Via: SIP/2.0/UDP 10.240.1.95:5060
;received=127.0.0.1;branch=z9hG4bK05952ee6;rport=5060
Max-Forwards: 69
From: "Anonymous" <sip:anonymous at anonymous.invalid>;tag=as7900b63f
To: <sip:eTden7KoNSdMVCUNYIwmz at wh2.24dial.com>
Contact: <sip:anonymous at 10.240.1.95:5060;alias=127.0.0.1~5060~1>
Call-ID: 0662d336694c60ed60ed5310571a1aee at 10.240.1.95:5060
CSeq: 102 INVITE
User-Agent: Asterisk PBX 11.13.1
Date: Mon, 03 Nov 2014 09:01:39 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO,
PUBLISH, MESSAGE
Supported: replaces, timer
Content-Type: application/sdp
Content-Length: 676
P-hint: outbound


As you can see, Kamailio uses 0.0.0.0 for Record-Route as well as for VIA
Header.
It uses the address configured in kamilio.cfg (listen=udp:0.0.0.0:5064)

I know, that we could use the advertise parameter to tell kamailio the
external IP. The problem is, that IPs in GCE are dynamically assigned to
the VMs. Thus static configuration of external IP is not sufficient for our
setup.

Is there a way, to let Kamailio gather it's external IP dynamically. (E.g.
using a STUN server or something like that?)

Another possibility would be to tell Kamailio it's external IP via a start
parameter. Is that possible?

Any help would be grateful.

Kind regards,
Marko Seidenglanz
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sip-router.org/pipermail/sr-users/attachments/20141103/09bd1d6d/attachment.html>