[asterisk-users] chan_sip sending from wrong source address when multiple interfaces are used

[Duncan Turnbull]

Similar problem
On 12/07/2012, at 4:36 PM, Jeff LaCoursiere wrote:

> On Thu, 2012-07-12 at 15:49 +1200, Alec Davis wrote:
>> I've seen similar.
>> 
>> We tried 4 interfaces. On 4 lans, are these considered to be overlapping?
>> 192.168.1.1
>> 192.168.2.1
>> 192.168.3.1
>> 192.168.4.1
>> 
> 
Running openvpn on asterisk server for a few remote users.

> Depends on the netmask you use :)  Assuming you used /24, so "no", they
> don't overlap.
> 
> This does exhibit the problem though.  Your OS stack assumes one of
> those addresses - the first identified interface? - is the one that all
> replies will appear to come from.  So phones on the 192.168.2.0/24
> network that try to register get replies from 192.168.1.1 and ignore
> them.
> 
The normal LAN phones get replied to using the standard LAN address, the ones over openvpn get a reply using the local openvpn address, which if they aren't expecting it they ignore

We got round it by setting the outbound proxy to the unexpected address and then everything seems happy - we are using Yealink though so it maybe different for other phones

You could use IP Tables I guess too

Cheers Duncan