For 2.2 kernels you'll have to look into ipfwadm...I think. I really don't
remember how to forward stuff in 2.2 kernels.

With 2.4 kernels it's really easy:
$IPTABLES -A PREROUTING -t nat -p tcp --dport 1012 -i eth0 -j DNAT --to
192.168.1.12:22

But tools like plonk aren't quite ready for iptables yet.

Andrew S. Zbikowski | http://www.ringworld.org
"We can learn much more from wise words, little
from wisecracks and less from wise guys."
--William Arthur Ward