This is my Debian/Ubuntu 64-bit desktop kernel version 4.1 patched with the PF patch. Disclaimer: I do not guarantee that this will work for you. I am making it available for everyone who is in the need of the latest PF kernel like I was.
So you made yourself anonymous with OpenVPN. You browse the world wide web blissfully. Unknown to you, your OpenVPN connection has broken and now your true IP is exposed all over the Internet. Scary! Here is a simple firewall script that you can use to protect yourself. This uses iptables on Linux.