ObdII socket

It pulls off. It has 5 or 6 quite tight, sprung push-fittings around it's edges which make a bit of a noise when pulled apart but don't usually suffer any damage. The port is angled towards the accelerator pedal.
 
You don't need to pull the panel off though. ;-)

Once you work out where it is, you'll see what I mean. Get your head in the driver's side footwell and look up.