[tlug] Question on iptables and port forwarding

[Ian Barwick <barwick@example.com>]

Hi all

I have two machines on the same local network, 192.168.2.6 and 192.168.2.7
and I want to forward say TCP connections to 192.168.2.7:12345 to 192.168.2.6:80
(just for the hell of it, it's Friday ;) ).

All available sources indicate I should be doing something like this
(on 192.168.2.7):

iptables -A PREROUTING  -i eth0 -t nat -p tcp --dport 12345 -m state
--state NEW,ESTABLISHED,RELATED -j DNAT --to 192.168.2.6:80
iptables -A FORWARD -i eth0 -p tcp --dport 80 -m state --state
NEW,ESTABLISHED,RELATED -j ACCEPT

but accessing 192.168.2.7:12345 just results in a timeout.

Both machines are running recent standard Ubuntu installations and
as far as I can tell, IP forwarding is enabled.

root@example.com:~# cat /proc/sys/net/ipv4/ip_forward
1

No other iptables rules exist on either of the machines.

Any ideas what I am doing wrong? Could it be a problem that for the
desired setup, 192.168.2.7 is not forwarding from one interface to another?

Thanks for any hints (this kind of stuff is not really my forte)


Ian Barwick