#!/bin/sh

# Set some variables
# Why? So if anything changes, you don't have to change
# every single instance of that IP in the script, you only have
# to change it in one place, and rerun the script for it to
# take effect.

  WEBSERVER="10.11.12.20"
  EXT_IP="1.2.3.5"

# Flush all preexisting portforwarding rules

  ipmasqadm portfw -f

# Do port forwarding for the server on ports 80 (http) and 443 (https)
# Note for readability I use the actual service names instead of the
# port numbers. Linux will automagically interpret the appropriate
# ports from the /etc/services file.
# Since the port forwarding code doesn't have anything like
# the '-b' switch in ipchains (meaning bidirectional), we have
# to make two separate statements for each port forwarded -
# one for incoming, and one for outgoing

  ipmasqadm portfw -a -P tcp -L $EXT_IP http -R $WEBSERVER http
  ipmasqadm portfw -a -P tcp -L $WEBSERVER http -R $EXT_IP http
  ipmasqadm portfw -a -P tcp -L $EXT_IP https -R $WEBSERVER https
  ipmasqadm portfw -a -P tcp -L $WEBSERVER https -R $EXT_IP https