[Blink] Improper outgoing interface representation on multihomed host

Saul Ibarra Corretge saul at ag-projects.com
Mon May 30 10:25:52 CEST 2011

Hi Alex,

On May 30, 2011, at 2:54 AM, Alex Balashov wrote:

> Greetings,
> I am using Blink 0.2.7 on Linux.  I think I've run into a problem with improper selection of outbound network interface information to present in SIP initial request bodies.
> I have a local network interface on a private network with address  I also have an OpenVPN tunnel interface tun0 with address over which a static route to my PBX is pinned in the system routing table, e.g.
>   route add -host addr.of.pbx gw dev tun0
> I am trying to place calls with Blink through that PBX.
> The problem is that even though the INVITE to the PBX does go out of tun0 from a Layer 3 perspective, obviously, all network and transport-layer address artifacts in the INVITE message body, such as, for example, the Via header, refer to the hardware interface address of

We are aware of the Via header issue, it's a limitation we have to live with, at least for now. Other fields such as c line should be correct, were they?

> From a practical perspective, I suppose the issue is somewhat academic;  it can be solved with a variety of conventional NAT-traversal strategies.  The PBX is Asterisk, so enabling nat=yes in particular would be an obvious fix.

Yes, that's right. Actually only by doing rport should be enough. Please let us know if you found incorrect information in the SIP messages other than in the Via header.


Saul Ibarra Corretge
AG Projects

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