[Asterisk-Users] Re: How far is IAX to be a Standard

[Adam Goryachev]

On Tue, 2004-11-02 at 20:57, Benjamin on Asterisk Mailing Lists wrote:
> On Tue, 02 Nov 2004 13:50:07 +0400, Jean-Michel Hiver
> <hiver.j at wanadoo.fr> wrote:
> > Out of interest, how would this work in a situation where two IAX
> > compliant devices (i.e. IAXy) are behind a non-configured natted network
> > (i.e. where no port forwarding has been setup)? Is it necessary to set
> > up port forwarding for IAXy's or an IAX enabled phone to work?
> 
> you would have to portforward at one end.

Actually, I assume the above (2 x IAX devices behind a single NAT
router) would work perfectly without any special configuration EXCEPT in
the (perhaps most common case) where both IAX devices are talking to the
same IAX server.

Wherever I have used the number 2, it could just as easily be any other
positive integer.

PS, The reason I say that is generally when we refer to NAT we also
refer to PAT (Port Address Translation <?>), so we end up with a table
like:

192.168.0.44:5436 -> 202.10.10.23:5436 -> 203.45.23.10:4569
192.168.0.45:5487 -> 202.10.10.23:5487 -> 203.55.32.10:4569

So, when the router sees a packet from 203.55.32.10:4569 it knows where
to forward it to (192.158.0.45).

Actually, extrapolating:
192.168.0.44:5436 -> 202.10.10.23:5436 -> 203.45.23.10:4569
192.168.0.45:5487 -> 202.10.10.23:5487 -> 203.45.23.10:4569

We still are ok, because the router will still appropriately translate
the incoming packets (looking at the destination as being
202.10.10.23:5487) as being for 192.168.0.45:5487

So, although I haven't tried it, I'm assuming it should work without any
problem.

The only thing tickling the back of my mind is that the outbound port on
IAX packets is always 4569, but one of these is going to be translated
by the PAT on the router to something else... I'm not sure if this
breaks anything.

Regards,
Adam