Re: Port forwarding with ipmasq and iptables

["Peter A. Felvegi" <felvegip@drmatrixbank.hu>]

hello,

 i did a different approach, but it may help you. i wrote a portforwarding
init.d script, that is started/stopped after ipmasq.

-BEG-----/etc/init.d/portforwarding---------
#! /bin/sh
#
# portforwading : sets up portforwarding from outer world to the lan machines
#
# 2003 Petschy

# args : srcip dstip dstport todstip todstport
function portforward
{
	iptables -t nat -A PREROUTING -p tcp --source $1 --destination $2 \
		--destination-port $3 -j DNAT --to-destination $4:$5
	echo " $1 -> $2:$3 -> $4:$5"
}
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
NAME=portforwarding

set -e

case "$1" in
  start)
	echo "Starting port forwarding"

	# two hostware machines to the polus palace db server port 3050
	portforward ....
	echo "Done."
	;;
  stop)
	echo -n "Stopping port forwarding : flushing PREROUTING chain"
	iptables -t nat -F PREROUTING
	echo "."
	;;
  *)
	N=/etc/init.d/$NAME
	echo "Usage: $N {start|stop}" >&2
	exit 1
	;;
esac

exit 0
-END-----/etc/init.d/portforwarding---------

i update only the PREROUTING chain, while you update the FORWARD chain,
too. why is that needed? did i miss something?

						cheers, petschy

> $IPTABLES -A PREROUTING -t nat -p tcp -d $IPOFIF --dport <port> -j DNAT
> --to-destination 10.0.0.2:<port>
>
> $IPTABLES -A FORWARD -p tcp -d $IPOFIF --dport <port> -m sate --state
> NEW -j ACCEPT