iptables -P OUTPUT DROP
iptables -t filter -A OUTPUT -o lo -j ACCEPT
iptables -t filter -A OUTPUT -o tun0 -j ACCEPT
iptables -I OUTPUT 1 -s !lo -j DROP 
iptables -I FORWARD 1 -j DROP
for i in `ip link show | awk '/^[0-9]+:/{DEV=$2} /link\/ether/{if(match(DEV,"(en|wl|eth|wlan)")>0){gsub(":","",DEV);print DEV}}'` ; do iptables -t filter -A OUTPUT -o $i -p $VPN_PROTOCOL --dport $VPN_PORT -j ACCEPT ; done