ONLY VPN traffic on F20 wireless interface?

[Steve Snyder]

How can I ensure that in Fedora 20 my wireless interface is *only* used 
for VPN traffic?

After the initial connection to the access point I want to guarantee 
that no traffic passes through the interface other than through the 
OpenVPN tunnel.

Ideally, I'd like to be able to ensure this from a terminal window, but 
use of a GUI interface is OK if that is what is needed to ensure no 
leakage of unencrypted data.

Can someone point me to a guide that explains how to do this?

Thanks.