OpenVPN refuses to start in LXC container

I was getting the following error when trying to start openvpn from within an LXC container:

Note: Cannot open TUN/TAP dev /dev/net/tun: No such file or directory (errno=2)

This fixed it:

mkdir /dev/net 
mknod /dev/net/tun c 10 200 
chmod 666 /dev/net/tun