A South African Boerboel?

im pretty experienced with big dogs and "protection mode". Its just their instincts. you need to be firm with bubba, and reward him when he does what you wish. barking is far better then ripping some guys arm off, so just make sure that your dog can have the freedom to bark at the people, but not have any stranger have freedom to pet bubba and risk its arm being ripped off. Treats work pretty well. show him the treats, and if he behaves (not literally attacking the car window to get out all because someone stepped to close to the car). i would also suggest that when and if you let strangers pat him, make sure they are not towering over him, or he'll feel threatened. try getting him used to people around him, or at least 'near' (walking past) your car with him in it. it'll calm him down. GOOD LUCK!!!