[asterisk-users] Newbie Planning Help

[Alan Chandler]

Excuse the ASCII diagramme - you will need a fixed width font to 
understand it.

 ------     -------                         -------     -----
 | A  | ==> | NAT | ===                 === | NAT | <== | B |
 ------     -------    |               |    -------     -----
                      -------------------
                      |  The Internet   |
                      -------------------
                                | WAN interface (82.44.22.127)
                          -------------
                          | S   (NAT) |
                          ------------- 
                               | LAN interface (192.168.0.20)
              =====================================
              |         192.168.0.0/24 range      |
            ------                             -------
            | C  |                             | D   |
            ------                             -------
I am at home on machine D (and with wife on machine C), with some family 
at machines A and B.

I am trying to setup an arrangement whereby clients on machines A, B, C 
and D can talk to each other on Softphones. A,B,C are are all Windows 
XP machines, machines D and S are linux.  This has to include A talking 
to B and ultimately conference calls with potentially all parties.

Machine S is my firewall/router providing NAT services to clients C and 
D (based soley on my own IPTABLES script) but is ALSO the machine I 
plan to put Asterisk on (it can therefore bind to two interfaces, with 
separate configurations for each if I so desire). If appropriate, I 
could install a STUN server on S.  I would prefer if media traffic 
between A and B avoids using my WAN interface pipe but if that is 
unavoidable, so be it.

I could use SIP or IAX softphones in this setup as long as it is no more 
complicated that telling A and B what to download and giving them 
simple setup instructions.  They could probably adjust their NAT 
routers to forward particular ports to them, but its not certain (A 
shares a flat with others).

I have a slight preference for SIP as it means I could potentially 
replace machines A,B and C with hardware devices in the future.

I have been round and round in circles reading the documentation but I 
am not sure I understand

a) to what extent Asterisk can manage everything necessary to allow 
machines A and B to communicate if they were SIP phones.  Is it 
possible to go for a setup with the firewalls/NAT devices as shown

b) if I go with IAX softphones, does communication between A and B have 
to go through S, or can Asterisk "hand-off" the IAX conversation so 
that A and B talk directly.

c) the example documentation shows seperate entries in iax.conf for 
incoming and outgoing calls.  In my case (assuming IAX softphones) 
would I just have entries for A and B of type friend?

Can someone give me some advice about how to proceed.

Thanks


-- 
Alan Chandler
http://www.chandlerfamily.org.uk