[Asterisk-Users] SIP Nat Issue

[Olle E. Johansson]

Chris Albertson wrote:

> X-Lite _can_ dail out to FWD through a firewall but Asterisk can't.
> SO this gives us the perfect chance to compare the content of
> outbound packets where we have a working and non-working example.

X-lite when configured for FWD behind a NAT uses an outbound proxy
for that connection. That means that ALL sip messages to anyone
go to the outbound proxy instead of any other proxy. Just
ignore doing SRV lookups, send everything outbound to one place.
Like a Web proxy server, that receives everything. X-lite have
a configuration that says "outbound if nat" - which is what
you do in a web browser - "don't use proxy if local address'.

> I'd look into hacking Asterisk to mimic the X-Lite generated
> SIP protocol.  
It's part of the SIP standard.
http://www.voip-info.org/wiki-SIP+outbound+proxy


> Put the result on the wiki.  Doing this will greatly speed up
> the fix.
http://www.voip-info.org/tiki-index.php?page=Asterisk+SIP+NAT+solutions
...as a start.

There's a pointer to my bug report on the wiki. Read it and make comments
on that page - it's easy to track changes there since changes are mailed
out.

/O