If you have the technical knowledge, you can make your own VPN kill switch using iptables and the UncomplicatedFirewall (UFW) app. There are lots of good step-by-step tutorials online to get you started. . If you prefer to let someone else do the hard work for you, PIA’s VPN app for linux includes a 100%-effective Kill Switch. All you have to do is enable it in the app settings and you’ll be fully protected against data leaks.