Re: conntrack manipulation

[Nils Ohlmeier <lists@ohlmeier.de>]

Hi Jozsef,

first of all thanks for thought and ideas.

On Monday 12 May 2003 09:35, Jozsef Kadlecsik wrote:
> On Sat, 10 May 2003, Nils Ohlmeier wrote:
> > Not phone1 sends but phone2 sends RTP packets immediately after it send
> > the '200 OK' to confirm that the user at phone2 picked up the hearer. So
> > the problem is basicly that the callee phone starts to send packets to
> > fast (at least to fast for our solution).
>
> Then enter the required rules when phone1 sends the command, without
> waiting for a confirmation from phone2. If phone2 would refuse the
> request, then delete the unnecessarily added rules.

For a call from internal to external (outbound) this would be possible if we 
insert DNAT rules with any source IP and port. But for inbound calls we have 
a problem, because with the SIP protocol you do not know the final 
destination (IP and port) if you see a traversing INVITE. So we can insert 
the DNAT rule only after we saw the SDP part of the 200 OK (or any other 1xx 
with a SDP body).

Regards
  Nils Ohlmeier