Replicant

#!/bin/sh

# Replicant USB Networking

# ========================                             

# 

# Copyright (C) 2011 Paul Kocialkowski, GPLv3+

# 

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

# 

# You should have received a copy of the GNU General Public License

# along with this program.  If not, see <http://www.gnu.org/licenses/>.

IPTABLES_CLEAN_RULES=true

USB_IFACE="usb0" 

INTERNET_IFACE="eth0" 

USB_IFACE_IP="192.168.4.200" 

# Clean iptables rules

iptables_rules_clean () {

    if [ $IPTABLES_CLEAN_RULES = false ]

    then

        return

    fi

    iptables --flush

    iptables --table nat --flush

    iptables --delete-chain

    iptables --table nat --delete-chain

}

# Inject iptables forwarding rules

iptables_forward_rules_apply () {

    iptables --table nat --append POSTROUTING --out-interface $INTERNET_IFACE -j MASQUERADE

    iptables --append FORWARD --in-interface $USB_IFACE -j ACCEPT

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

}

# Configure network link

usb_networking_configure () {

    ifconfig $USB_IFACE up

    ifconfig $USB_IFACE $USB_IFACE_IP

}

usb_networking_disable () {

    ifconfig $USB_IFACE down

    echo 0 > /proc/sys/net/ipv4/ip_forward 

}

case $1 in

    "start")

        echo "Starting Replicant USB Networking" 

        iptables_rules_clean

        usb_networking_configure

        iptables_forward_rules_apply

    ;;

    "stop")

        echo "Stopping Replicant USB Networking" 

        usb_networking_disable

        iptables_rules_clean

    ;;

    *)

        echo "Usage: sh $0 {start|stop}" 

    ;;

esac