[NTLUG:Discuss] Firewall Forwarding Question

[David]

What's been missing in all this is that with iptables, "forward" is
the wrong table to put this sort of thing in.  What's really needed
here is the iptables "DNAT" option, which is only valid in the "nat"
table.

Here's the commands I'd suggest:

iptables -t nat -A PREROUTING -p udp -s {host-A} --dport 540 \
	 -j DNAT --to-destination {host-C}:540

iptables -t nat -A PREROUTING -p udp -s {host-B} --dport 540 \
	 -j DNAT --to-destination {host-C}:540

You'll need to have the ip_conntrack and ip_nat modules in your
kernel.

-- 
David Hayes
david at hayes-family.org