My dog knows sit, down, stay, here... That's about it. Well, he knows how to bark and warn me about unfamiliar things. When he sees an unfamiliar vehicle at a neighbor's house, he kicks up a fuss until I calm him down.
He is a watchdog for the whole neighborhood, not just our place. If something is out of place (to his mind), he let's me know. Our several-times-daily strolls around the rural roads here give him a chance to do his stuff. There is a nice place near here that is owned by a guy from RI who is rarely around. He came up for hunting season and when Duke saw the guy's truck in the driveway, his back fur got up, and he started barking. Pretty good security system. The guy was pretty impressed. He'd probably pay for a daily security-detail.