ics.sh

#!/bin/bash
#
# ics.sh
# This script sets up internet connection sharing using two network interfaces.
# It uses iptables to set up ics.  The script needs to be run as root.
# There are three mandatory arguments required:
# -i Internet Interface  i.e ethernet
# -e Sharing Interface  i.e wifi in AP mode
# -a Sharing Interfaces ip address
# The script assumes that your broadcast address is in the form of x.y.z.255
# and your network is range is x.y.z.a/24
#
# It is intended as a wrapper for Easy Firewall Generator script output
# http://easyfwgen.morizot.net/gen/index.php
#####

# Check if any arguments are given, otherwise send out help message.
if [ -z "$1" ]; then
        printf "Usage: $0 -i [Internet Interface] -e [Sharing Interface] -a [Sharing IP Address]\n"
        printf "i.e:  $0 -i eth0 -e wlan0 -a 10.0.0.1\n"
        exit 1
fi

# File arguments to correct parameters using getopts
while getopts  "a:e:i:" opt
        do
                case $opt in
                a ) LOCAL_IP=${OPTARG};;
                e ) LOCAL_IFACE=${OPTARG};;
                i ) INET_IFACE=${OPTARG};;
                \?) printf "Usage: $0 -i [Internet Interface] -e [Sharing Interface] -a [Sharing IP Address]\n"
                        exit 1;;
                * ) printf "Usage: $0 -i [Internet Interface] -e [Sharing Interface] -a [Sharing IP Address]\n"
                        exit 1;;
                esac
        done

#
# Check if root.
#
if [ "$(id -u)" != "0" ]; then
        printf "This script must be run as root\n" 1>&2
        exit 1
fi

#
# Check if all arguments are entered.
#
if [ -z "$LOCAL_IP" ] || [ -z "$LOCAL_IFACE" ] || [ -z "$INET_IFACE" ]; then
printf "Missing Argument/s!\nUsage: $0 -i [Internet Interface] -e [Local Interface] -a [Local IP Address]\n"
exit 1
fi

LOCAL_BCAST=$(echo $LOCAL_IP | sed 's/\.[0-9]*$/.255/')
LOCAL_NET=$(echo $LOCAL_IP | sed 's/\.[0-9]*$/.1\/24/')

printf "Local IP is $LOCAL_IP\n"
printf "Local network Inteface is $LOCAL_IFACE\n"
printf "Internet Interface is $INET_IFACE\n"
printf "Local broadcast IP is $LOCAL_BCAST\n"
printf "Local IP network range is $LOCAL_NET\n"
printf "Starting iptables configuration...\n"

exit

######
# Paste your generated IPTables script from easyfwgen.morizot.net here, just remember to comment out
# "Local Interface Information" and # Internet Interface sections so the above
# script can insert your values into the firewall.
######