My dog, Max, already has most of these behaviors. I live in a rural, isolated location so I want him to bark when someone unfamiliar comes to my house. You don't get here by accident. Usually I don't have more than one visitor in two weeks. After proper introduction I can take Max off the leash without any worry. Maybe if they made an aggressive move then he might respond in a protective manner, I've never tried it. Usually visitors are already intimidated by his size, 120 pounds.