Looking to tap the infinite wisdom of the CSC.

I have a 1998 Isuzu Rodeo and the rear differential is leaking. It's leaking where the drive shaft goes in, in the front. It seems like it's a seal/gasket sort of thing that is broken/ripped (although I can't see it to confirm) and the diff oil is coming out of there. The fluid is all over the area where the drive shaft goes in from the spinning. The leak isn't very fast but if it sits for a few hours there is a tiny puddle under the vehicle.

Anyone have experience with this?
Does it sound like a seal that's worn/broken?
If it is that, is it something I should be able to fix myself?

Any insight would be great!
Thanks.