[Asterisk-Users] Restricting/Negotiating H323 Port Ranges

[woody+asterisk at solutionsfirst.com.au]

> -----Original Message-----
> From: asterisk-users-admin at lists.digium.com 
> [mailto:asterisk-users-admin at lists.digium.com] On Behalf Of 
> Michael Manousos
> Sent: Wednesday, 21 January 2004 21:57
> To: asterisk-users at lists.digium.com
> Subject: Re: [Asterisk-Users] Restricting/Negotiating H323 Port Ranges
> 
> 
> Some notes regarding asterisk-oh323:
> 
> woody+asterisk at solutionsfirst.com.au wrote:
> > Our VoIP provider wants to use a restricted set of ports 
> for H323.  All
> > their current users have hardware at the customer premises 
> which does this
> > successfully for them.
> > 
> > We are trying to set up Asterisk to do the same (with their 
> co-operation).
> > 
> > I am not familiar with the H323 terms for these 
> connections, so bear with
> > me...
> > 
> > The (Connect/Listen) Port is 1720 (set in (o)h323.conf)
> > Tcp Range 10000-50000 (set in oh323.conf or rtp.conf)
> 
> This port range is used for call control (H.245). The ports which
> are used during an active connection are determined at startup and
> send to the remote endpoint.
> 
> > Udp Range 10000-50000 (set in oh323.conf or rtp.conf)
> 
> This port range is used for the interaction with the gatekeeper (RAS).
> It doesn't include the ports used by RTP. These are taken from
> rtp.conf.
> 
> > 
> > Now my tcp dump shows this with oh323 when I try to make a call to
> > number at provider:
> > 
> > Connect from high range port (10006) to provider 1720
> > They have a few exchanges....
> > 
> > Then asterisk connects from port 10007 to provider:2033
> > 
> > My provider wants this to be port 2020 all the time, but 
> the port number
> > just keeps increasing by one.
> > 
> > So the next call will involve a port of 2034 at their end.
> 
> If this is their port, you can't do anything about it.

This is their port which I connect to.  I guess the endpoints negotiate to
use that port in the traffic over port 1720.  Is there anyway to negotiate
for port 2020 only?  I guess this is what their customer boxes do.

What is this middle port range for?

> > Is there somewhere in either channel to restrict this 
> middle port range to
> > just 2020?
> > 
> > Or is there some negotiation which asterisk/openh323 
> libraries don't do?

Cheers,
Woody