(Ubuntu) VPN, Firewall block

ufw-vpn.sh

#! /bin/bash

# Functions needed for this script
is_valid_ipv4() {
  local -a octets=( ${1//\./ } )
  local RETURNVALUE=0

  # return an error if the IP doesn't have exactly 4 octets
  [[ ${#octets[@]} -ne 4 ]] && return 1

  for octet in ${octets[@]}
  do
    if [[ ${octet} =~ ^[0-9]{1,3}$ ]]
    then # shift number by 8 bits, anything larger than 255 will be > 0
      ((RETURNVALUE += octet>>8 ))
    else # octet wasn't numeric, return error
      return 1
    fi
  done
  return ${RETURNVALUE}
}


# Connect to vpn
nmcli con up id Anon

#Get ip so we can bind it to rtorrent
read ip <<< $(/sbin/ifconfig tap 2>&1 | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}')

echo "$ip"


is_valid_ipv4 ${ip}
if [[ $? -gt 0 ]]
then
        echo "Invalid IP, something is wrong the connection."
else
        echo "IP is valid, lets enable firewall."
        sudo ufw enable
        sudo ufw deny in on eth0
        sudo ufw deny out on eth0
        sudo ufw status verbose
fi




# Credits
# http://www.dopefish.de/archives/1180
# http://ubuntuforums.org/showthread.php?t=1154442