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

[Daniel-Constantin Mierla]

Hello,

On 03/11/14 10:43, Marko Seidenglanz wrote:
> 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
> <mailto:sip%3AeTden7KoNSdMVCUNYIwmz 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
> <mailto:sip%3AeTden7KoNSdMVCUNYIwmz 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
> <http://0662d336694c60ed60ed5310571a1aee@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
> <http://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?

you can give the advertised address as part of the listen parameter:

listen=udp:localip:port advertise publicip:port

You can define tokens in kamailio configuration file via command line
parameter -A (see kamailio -h).

Cheers,
Daniel

-- 
Daniel-Constantin Mierla
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Nov 24-27, Berlin - http://www.asipto.com

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