iptables redirection

[mallikk_in]

Hi,

i have something quite simple: I have one host with an ipaddress and one NIC.
now I would like that certain ports of that machine (25/80/110/143/443)
would be redirected to some other machine, because that one is replacing
the other, and I do not wish that there is any interruption in traffic.

so machine A has: 212.0.1.1 and one NIC
and machine B has: 121.0.2.2 and one NIC.

now i'm reading things like:
iptables -t nat -A PREROUTING -d 212.0.1.1 -p tcp \
--dport 80 -j DNAT --to-destination 121.0.2.2

which doesn't work.

what does work is something like:
iptables -t nat -A OUTPUT -d 212.0.1.1 -j DNAT --to \
121.0.2.2

but thats only for traffic which comes from the host itself, not for
foreign traffic that is going to the host.

hope someone can help.

[p1c0]

Perhaps you should add a rule in FORWARD chain...