I don't get the downvotes for this. A dog who doesn't like strangers is a pretty traditional security system, and is much, much more secure than a locked door.
It really really isn't. That stranger can become an instant friend with some food. There was a show once where an ex-burglar would break into people's homes to show how easy it was. People would say, "there's no way he's getting past my dog!" and the guy would just open up the fridge and throw all the meat on the floor. End of problem.
