Help setting up a VPN Kill switch on Ubuntu 16.04 LST 64 Bit

I am writing because i am using NordVPN through OpenVPN on my Ubuntu 16.04 64Bit machine. The issue i am having is there is no proper V.P.N. kill switch, so, i am here to ask for some help please in configuring a proper kill switch so if my V.P.N. drops, all of my internet connections drop until i manually (automatically if possible), re-connect my VPN connection “tun0”.

I know from my research it can be done either with Ferm and/or IPTables, and the tutorials associated with them are not user-friendly. If anyone can please help me with this that would be wonderful.

Any help will be greatly appreciated.