Script to configure NordVPN using OpenVPN on DD-WRT

build.sh

#!/usr/bin/env bash
# Script to initialize OpenVPN on DD-WRT firmware

TUN=tun0
ROUTER_USER=root
ROUTER_HOST=192.168.1.1
ROUTER_SSH=$ROUTER_USER@$ROUTER_HOST
CONFIG_URL=https://nordvpn.com/api/files/zip

# Pipe input to a file on the router
function pipeFile() {
   ssh -q $ROUTER_SSH "cat > $1"
}

# Clean up configuration stuff
function cleanUp() {
  rv=$?
  rm -rf $server_config_home
  exit $rv
}

read -p "Enter server: " server_prefix

server_config_home=`mktemp -d`
server_config_zip=$server_config_home/config.zip
server_config=$server_config_home/${server_prefix}.ovpn
trap cleanUp INT TERM EXIT

echo Downloading configuration...
wget -q --show-progress -O $server_config_zip $CONFIG_URL
unzip -p $server_config_zip ${server_prefix}.nordvpn.com.udp1194.ovpn > $server_config

if [ ! -f $server_config ]; then
  echo Server does not exist
  exit 1
fi

read -p "Enter username: " username
read -s -p "Enter password: " password
echo -e "\n"

echo Copying files...
echo -e "$username\n$password" | pipeFile openvpn_auth.txt
echo -e "#!/bin/sh \n iptables -t nat -I POSTROUTING -o $TUN -j MASQUERADE" | pipeFile route-up.sh
echo -e "#!/bin/sh \n iptables -t nat -D POSTROUTING -o $TUN -j MASQUERADE" | pipeFile route-down.sh
echo -e '#!/bin/sh \n killall openvpn ; openvpn --config nordvpn.ovpn --route-up `pwd`/route-up.sh --route-pre-down `pwd`/route-down.sh --script-security 2' | pipeFile vpn.sh
< $server_config sed -E "s/^(auth-user-pass)/\1 openvpn_auth.txt/" | pipeFile nordvpn.ovpn

echo Starting...
ssh -q $ROUTER_SSH "
if [ \`nvram get openvpncl_enable\` != 0 ]; then
 echo Disabling OpenVPN UI; nvram set openvpncl_enable=0
 nvram commit
 sleep 10
fi
chmod 600 openvpn_auth.txt nordvpn.ovpn
chmod 700 route-up.sh route-down.sh vpn.sh
nohup ./vpn.sh < /dev/null > openvpn.log 2>&1 &
"
echo Done