On Tue, Jun 25, 2002 at 09:01:03PM +0200, Admin wrote:

> Hi, I have no idea if if this is possible or not, but I would appreciate 
> some suggestions:
> 
> I have a server running inside our LAN and I want to be able to connect 
> to a particular daemon on this server, listening on port 5432, from 
> outside the LAN through the firewall.
> I've set up port forwarding to DNAT traffic destined for this port to 
> the LAN server. This works fine however the application opens up a 
> second 'data channel' similar to port based ftp but between two 
> unprivileged ports on the client and server.
> Is there any way to cater for this secondary connection and also do the 
> DNAT ?

If this second connection is incoming and to a static port you can
set up a second DNAT for that.

If this second connection is outgoing and from a static port you can
set up an SNAT for that.

If this second connection is to/from a dynamic port then you're
kind of out of luck and need a conntrack module (like ip_conntrack_ftp)
to do the job.

However, if you had a second valid IP then you could nail up a DNAT/SNAT
for that host...

Ramin

> Thanks
> Phill
> 

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