Re: [opensuse] Howto Use/Relay Ports to Connect to Other Computers from Outside?

On Sat, 21 Feb 2009 10:37:59 David C. Rankin wrote:
Listmates:

I guess this situation is a port forwarding situation, but I'm not sure
how to attack the problem. I have a limited number of IP entries in my
router that I can use to forward traffic through to other machines on my
office LAN from the outside. I need to learn how to setup ports on my
primary server that will send/receive information to and from other
computers on the lan. What is the best way to do this?

In the past the only experience I have had with this is ssh port
forwarding to forward X or reach other machines behind the router. Is that
what I need to do even though the traffic isn't ssh?

Do I need to set up IP tables? Can I do that with SuSEfirewall?

The layout I need is like this:


internet server port:12344
<==============>[ ]<----------------->[ ] client1 port:12345

|\
| \<---------------->[ ] client2 port:12346
|\
| \<---------------->[ ] client3 port:12347

[ ]
client4
port:12348

What mechanism do I need to go learn so that I can set up something like
this generically without relying on ssh only?


David,

IPtables is what you're looking for. I don't know if you can setup port
forwarding rules using Yast/SuSEFirewall as I've never actually used that. I
use my router's firewall and prior to that I used IPCop.

You may run into problems though if you're trying to do multiple levels of
port forwarding (i.e. from the router -> server -> clients). I've tried that
here with my Belkin VoIP router/DSL modem forwarding to my Linksys WRT54GL
wireless router (running HyperWRT firmware) and then to the clients on the
LAN; so far I've not been able to make it work (but I haven't tried too hard
to debug it, either).

For sorting it out, wireshark will be your friend.

BTW, IPCop is a firewall-specific distro that is well worth checking out for a
dedicated firewall machine. It uses IPtables but adds a web front end for
management and its functionality can be easily extended to add things like
squid (web proxy), content filtering (a couple of options) and lots of others.
The web front end makes it easy to set up quite complex ip tables
configurations and you can always ssh into it to massage the config files
manually if need be.

Regards,
Rodney.

--
===================================================
Rodney Baker VK5ZTV
rodney.baker@xxxxxxxxxxxx
===================================================


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