[Bayonne-devel] SIP NAT port forwarding and Bayonne2 1.0.6/1.1.6 & VOIP providers

[David Sugar]

The next release will include support for registering with a public
proxy from behind a port forwarded NAT.  This will be done by adding the
public= option to your registration statement, which is used to define
the "public" internet host address your server appears under.  Bayonne2
will also perform the rewrite of the sdp, and if a dynamic host provider
is used rather than a IP address for your public=, it will resolve and
use the current public ip address (for dynamic sites).

Port forwarding for Bayonne SIP is simple because the rtp session ports
by default are behind the selected port number for SIP.  Hence, both the
sip port and the rtp ports can be forwarded through your NAT/firewall
together as a single contiguous block.

Individual scripts can be registered simultaneously both with public
proxies and private ones behind the NAT.  Those calls coming from the
public proxy will get rewrite rules applied, and those from the private
ones will not.

I also fixed a problem I found in Bayonne SIP call classification, and 
I have created an explicit proxy authorized call session type as a
result, which differs from peer authorized.

While I could have used STUN, this requires a STUN server you have
access to, and I deemed it unneeded in this case, because while one may
run individual arbitrary voip clients at any time from any machine
behind a NAT, one is not likely to have arbitrary servers started and
stopped all the time.

This should also make it easy for a home or small office to experiment
with and deploy Bayonne2 for use in conjunction with an existing SIP
based VOIP provider.