[Asterisk-Users] iax behind a SonicWall

[John Todd]

At 8:23 PM -0600 on 5/12/04, Rich Adamson wrote:
>Current dev cvs install on two systems. System A is behind a SonicWall
>firewall, and system B is on a registered IP address. (System B has
>multiple iax links that are fully functional to multiple locations.)
>
>System A is correctly registering with System B, with no special firewall
>rules.
>
>Should System B be able to take advantage of the "registration" to send
>iax/gsm calls to System A without installing any firewall rules?
>
>I assumed it could, but an ethereal trace indicates a new call is
>placed from B -> A, but A never acknowledges the iax2 packet, etc.
>
>The trace suggests the registration is happening with
>  src port 28277 (or whatever) -> dest port 4569
>however, calls are processed with
>  src port 4569 and dest port 4569
>
>Shouldn't we expect src=4569 and dest=4569 on all iax2 interactions?
>
>Rich

If src=4569 and dst=4569 always, then it would be impossible to have 
more than one IAX2 talker behind a firewall talking to an external 
Asterisk server, right?  There would be no method by which the 
firewall would "know" which packet was destined for what device 
inside the firewall, since the source port and destination port would 
be the same for each "connection".   I'm not thinking this through 
completely, and it seems like there is a flaw in this argument... but 
with UDP, there is no sequence number that should have attention paid 
to it (like TCP) so... er... someone tell me why this is incorrect.

note: firewall in this case is really "NAT", right?

JT