#!/bin/sh
#
#
#

if [ -n "$1" ]; then

    IPTABLES=/sbin/iptables

    sudo echo 1 > /proc/sys/net/ipv4/ip_forward

    # Flush nat table
    # $IPTABLES -t nat -F

    sudo $IPTABLES -t nat -I PREROUTING --dst $1 -p tcp --dport $2 -j DNAT --to-destination $4:$5
    sudo $IPTABLES -t nat -I POSTROUTING --dst $4 -p tcp --dport $5 -j SNAT --to-source $3
    sudo $IPTABLES -I FORWARD 1 --dst $4 -p tcp --dport $5 -j ACCEPT

    echo "Done"

    exit 1

fi

echo 'Utility ip-forward-tunneling terutama untuk openvpn'
echo 'Usage :'
echo '#ip-forward-tunneling public_ip public_port tunnel_ip tunnel_to_ip tunnel_to_port'
echo ''

exit 1