azureus port forwarding problem

[Gerhard Magnus]

On Wed, 2006-09-06 at 09:28 -0700, Steven Ellis wrote:
> Gerhard Magnus wrote:
> > I'm trying to set up Azureus using the Stanton Finley installation notes
> > (http://stanton-finley.net/fedora_core_5_installation_notes.html).  I
> > have 3 linux boxes (192.168.1.11-13) behind a router (192.168.1.1) and a
> > DSL modem (192.168.0.1).  I've followed the instructions for modifying
> > iptables to open TCP ports 6881-6999 and a single UDP port in that range
> > -- I've chosen UDP port 6973.
> >  
> I believe that the recommendation is now to _avoid_ using ports 6881 to 
> 6999...

> > Here's how I've set up port forwarding on the DSL modem and the router:
> >
> > The DSL Actiontec modem has a "Port Forwarding" page on which I've added
> > these two lines to the "List of Forwarded Ports", where 192.168.1.1 is
> > the address of the router:
> > 6881-6999 tcp 192.168.1.1
> > 6973-6973 udp 192.168.1.1
> >
> > The Linksys router has a "Port Range Forwarding" page on which I've
> > added these two entries, where 192.168.1.12 is the address of the Linux
> > box where I want to use Azureus and bittorrent:
> > 6881-6999 tcp 192.168.1.12
> > 6973-6973 udp 192.168.1.12
> >
> >   
> I guess I'm confused as to how the router and the DSL modem are 
> connected to your network--If the DSL modem is doing NAT for you, and so 
> is the router (rather odd, but should work), then you may have things 
> set correctly, but then the router is using two interfaces, perhaps 
> 192.168.0.X connected to the DSL modem, and 192.168.1.1 connected to the 
> linux machines--if so, you probably want to have the DSL modem forward 
> to 192.168.0.X (whatever the router's address is on that subnet)--the 
> DSL modem likely doesn't know about the 192.168.1.X network.
> 
I think this is exactly what's happening: the modem sees the router as
192.168.0.3 while the Linux machines see the router as 192.168.1.1.  How
is this address 192.168.0.3 assigned?  Where does the translation to
192.168.1.1 occur?

> If you aren't running NAT on both the DSL modem and the router, then you 
> likely only need port forwarding configured on the one that is doing NAT 
> (the router, I'm guessing).

The DSL modem provided by the phone company has only one output, which
has forced me to use a router to connect my local network.  I would like
to use a more standard configuration for the modem and router, as it
might make troubleshooting problems like this one with azureus easier.
I assume this means having NAT running only on the router.

The DSL modem has a static IP address assigned by my ISP.  My boxes on
the LAN also have static addresses.

I've tried changing settings on the router and modem but then I can't
reach the net from the LAN.

Any suggestions as to how to proceed in making this configuration more
standard (and transparent to this user) would be much appreciated.

Jerry