When I first bought my GL-MT300N-V2 and used OVPN with it, there was a nice little Kill Switch button, but since I upgraded to 3.012 some time ago there is no Kill Switch button, and when my VPN fails it just defaults to my regular connection. I have read that the Kill Switch is always on with 3.x, but I would say that is definitely not the case for me. How can I make the Kill Switch work?
Just use iptables. Drop everything except 53 and 1194 and be sure to run OpenVPN on 1194.
Works perfectly every time.
iptables -I FORWARD 1 -p tcp --dport 1:52 -j DROP
iptables -I FORWARD 1 -p udp --dport 1:52 -j DROP
iptables -I FORWARD 1 -p tcp --dport 54:1193 -j DROP
iptables -I FORWARD 1 -p udp --dport 54:1193 -j DROP
iptables -I FORWARD 1 -p tcp --dport 1195:521722 -j DROP
iptables -I FORWARD 1 -p udp --dport 1195:521722 -j DROP