asterisk users - Aug 2003 - Has anyone got sip/IAX working behind a firewall?

I have read loads of the emails on the subject but have not read a setup I
could use.

I have a windows box using Winproxy to dial up the internet through a DSL
modem. My internal network I am using while developing.


My internet network has been renumbered so that I could test using
Nikotel4Mac. It will only accept certain numbering schemes so I have changed
my ip's on the internal network to be 192.168.0.x

Winproxy gets the external ip when it dials up.

External (x.x.x.x) -> Winproxy (192.168.0.1) -> Linux (192.168.0.2)
External (x.x.x.x) -> Winproxy (192.168.0.1) -> Windows (192.168.0.3)
External (x.x.x.x) -> Winproxy (192.168.0.1) -> 54g radio (192.168.0.4)
External (x.x.x.x) -> Winproxy (192.168.0.1) -> Mac OSX (192.168.0.6)

Do I need to setup Winproxy so that it forwards incoming connections to
asterisk on Linux?

I understand that I can setup IAX to register it's connections with
iaxtel.com but so far it does not make the connection.

There is also lots of discussions saying that sip cannot work this way
round. Is this true?

I cannot put linux outside the firewall unless I change my configuration so
that linux dials the net. However it is still dialling with a dynamic
address so I will never know what this address is.

I have also looked at the Mac OSX IAX beta soft phone called WX but that
will not work either.

Since I am testing using soft phones not hardware phones it all comes down
to the numbering and getting the firewall to correctly send the connection
requests to the right applications on the right machines.

Has anyone got a similar setup working?

Thanks
Fats.

I use asterisk behind my Linux firewall with no problem.  For IAX I have 
the firewall forward udp port 5036 to the asterisk box. Really simple nat 
setup.  My asterisk box also connects to other asterisk/IAX servers 
through nat from behind the firewall.  I'm not sure about sip at all but I 
know that IAX works fine.  I don't know anything about Winproxy but I 
would assume you could easily masquerade outgoing packets/connections and 
then for incoming connections forward port udp 5036 to your asterisk box.
AJ