#!/bin/bash
tempDir='/tmp/nord'
serversIpList='serversIpList'
enableKillSwitchScript='/home/goog/Documents/Enable_VPN_Kill_Switch.sh'
wifiInterfaceName='wlp2s0'
connectionProtocol='udp'
connectionPort='1194'
linkToOvpnZip='https://nordvpn.com/api/files/zip'
# Download new IP list
printf "\nCreating temporary directory"
mkdir $tempDir
printf "\nDownloading new VPN config files\n"
wget --directory-prefix=$tempDir $linkToOvpnZip
printf "\nExtracting IPs from config files"
unzip -q $tempDir/zip -d $tempDir
grep -h "remote " $tempDir/*ovpn | cut -d ' ' -f 2 | sort -u > $tempDir/$serversIpList
#Create script that will enable kill switch$enableKillSwitchScript
printf "\nCreating new Kill Switch Script"
rm -f $enableKillSwitchScript
touch $enableKillSwitchScript
echo "#!/bin/bash" >> $enableKillSwitchScript
echo "iptables --flush" >> $enableKillSwitchScript
echo "iptables --delete-chain" >> $enableKillSwitchScript
echo "iptables -t nat --flush" >> $enableKillSwitchScript
echo "iptables -t nat --delete-chain" >> $enableKillSwitchScript
echo "iptables -P OUTPUT DROP" >> $enableKillSwitchScript
echo "iptables -A INPUT -j ACCEPT -i lo" >> $enableKillSwitchScript
echo "iptables -A OUTPUT -j ACCEPT -o lo" >> $enableKillSwitchScript
IP_LIST=$(tr '\n' ' ' < $tempDir/$serversIpList)
for IP in $IP_LIST; do
  echo "echo 'adding rules for IP: $IP'" >> $enableKillSwitchScript
  echo "iptables -A OUTPUT -j ACCEPT -d $IP/27 -o $wifiInterfaceName -p $connectionProtocol -m $connectionProtocol --dport $connectionPort" >> $enableKillSwitchScript
  echo "iptables -A INPUT -j ACCEPT -s $IP/27 -i $wifiInterfaceName -p $connectionProtocol -m $connectionProtocol --sport $connectionPort" >> $enableKillSwitchScript
done
echo "iptables -A INPUT -j ACCEPT -i tun0" >> $enableKillSwitchScript
echo "iptables -A OUTPUT -j ACCEPT -o tun0" >> $enableKillSwitchScript
echo "iptables -A INPUT --src 192.168.0.0/24 -j ACCEPT -i $wifiInterfaceName" >> $enableKillSwitchScript
echo "iptables -A OUTPUT -d 192.168.0.0/24 -j ACCEPT -o $wifiInterfaceName" >> $enableKillSwitchScript

echo "iptables -A INPUT -j DROP" >> $enableKillSwitchScript
echo "iptables -A OUTPUT -j DROP" >> $enableKillSwitchScript
echo "printf '\nVPN Kill Switch Enabled!\n'" >> $enableKillSwitchScript

printf "\nClening up"
chmod 744 $enableKillSwitchScript
rm -rf $tempDir
printf "\nDone. \nKill Switch Script is here: $enableKillSwitchScript\n"