One tecnique is wait and see if they kill your dog....if they do they are legitamate, but wait home invaders dressed like ersatz Task force guys do the same thing... Ok, so the dog thing isnt a good way to judge.
ok, ok I got it...meet them at the front door and point a gun..if they are legit, they will shoot you full of holes. Well, wait...the ersatz task force guys will do the same thing. hmmmmmm.
Ok, i'm at a loss here....if you resist, both will hurt you...If you don't resist, you and your dog can still be killed.
You are simply not going to get the upper hand with a bedside pistol....it would take a ultra violent military grade response (tossing fragmentation grenades, spraying massive amounts of high penetration beltfed gunfire through walls to the point that the invaders are pretty sure they arent going to live over this)
None of which is neibor friendly, and your property insurance is going to go though the roof
( did i mention the foogas?)