#!/bin/bash

host6=$(dig AAAA +short <TPL:SERVER_NAME> | tail -n1)
host4=$(dig A +short <TPL:SERVER_NAME> | tail -n1)

# IPv6

sudo ip6tables -N vpnclient_in
sudo ip6tables -N vpnclient_out
sudo ip6tables -N vpnclient_fwd

sudo ip6tables -A vpnclient_in -p icmpv6 -j ACCEPT
sudo ip6tables -A vpnclient_in -s fd00::/8,fe80::/10 -j ACCEPT
sudo ip6tables -A vpnclient_in -p tcp --dport 22 -j ACCEPT
sudo ip6tables -A vpnclient_in -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
sudo ip6tables -A vpnclient_in -j DROP

if [ ! -z "${host6}" ]; then
  sudo ip6tables -A vpnclient_out -d ${host6} -p <TPL:PROTO> --dport <TPL:SERVER_PORT> -j ACCEPT
fi

sudo ip6tables -A vpnclient_out -d fd00::/8,fe80::/10 -j ACCEPT
sudo ip6tables -A vpnclient_out -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
sudo ip6tables -A vpnclient_out -j DROP

sudo ip6tables -A vpnclient_fwd -j DROP

sudo ip6tables -I INPUT 1 -i <TPL:WIRED_DEVICE> -j vpnclient_in
sudo ip6tables -I OUTPUT 1 -o <TPL:WIRED_DEVICE> -j vpnclient_out
sudo ip6tables -I FORWARD 1 -o <TPL:WIRED_DEVICE> -j vpnclient_fwd

# IPv4

sudo iptables -N vpnclient_in
sudo iptables -N vpnclient_out
sudo iptables -N vpnclient_fwd

sudo iptables -A vpnclient_in -p icmp -j ACCEPT
sudo iptables -A vpnclient_in -s 10.0.0.0/8,172.16.0.0/12,192.168.0.0/16,169.254.0.0/16 -j ACCEPT
sudo iptables -A vpnclient_in -p tcp --dport 22 -j ACCEPT
sudo iptables -A vpnclient_in -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A vpnclient_in -j DROP

if [ ! -z "${host4}" ]; then
  sudo iptables -A vpnclient_out -d ${host4} -p <TPL:PROTO> --dport <TPL:SERVER_PORT> -j ACCEPT
fi

sudo iptables -A vpnclient_out -d 10.0.0.0/8,172.16.0.0/12,192.168.0.0/16,169.254.0.0/16 -j ACCEPT
sudo iptables -A vpnclient_out -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A vpnclient_out -j DROP

sudo iptables -A vpnclient_fwd -j DROP

sudo iptables -I INPUT 1 -i <TPL:WIRED_DEVICE> -j vpnclient_in
sudo iptables -I OUTPUT 1 -o <TPL:WIRED_DEVICE> -j vpnclient_out
sudo iptables -I FORWARD 1 -o  <TPL:WIRED_DEVICE> -j vpnclient_fwd

exit 0