asterisk users - Jan 2004 - Restricting/Negotiating H323 Port Ranges

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)
Udp Range 10000-50000 (set in oh323.conf or rtp.conf)

Now my tcp dump shows this with oh323 when I try to make a call to
number@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.

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

chan_openh323 uses it's own RTP stack, not Asterisk's RTP stack.  The
chan_h323 can comes with Asterisk uses Asterisk's RTP stack.

On Tue, 2004-01-20 at 19:12, woody+asterisk@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)
> Udp Range 10000-50000 (set in oh323.conf or rtp.conf)
> 
> Now my tcp dump shows this with oh323 when I try to make a call to
> number@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.
> 
> 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
> 
> 
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Some notes regarding asterisk-oh323:

woody+asterisk@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@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.
> 
> 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
> 

Regards,
Michael.