Aggresive behavior is hard to deal with. You need to show him who is the pack leader. Some advice: Take him for an hour walk the right way (you in front or beside him) at least twice a day. He will learn you are the leader. Also by your body energy. You have to believe like a pack leader in order for your dog to feel your energy and summit. When your dog has bad behavior, alway be consistant and correct him calm-assertively. Here is a hint also, cup your hand so your nails are like the top jaw of your mouth, then give him a quick bit to correct unwanted behavior. It won't hurt him, but will show him you are in charge. Also by making grunts or growl sound at the same time. You are mimicking the pack leader by doing this. Remember be calm-assertive at all times. The walking is very improtant in you becoming the pack leader. Think of it like a wolf would. The Pack leader is always in charge and correctes when needed without fail. The leader always walks with there pack and the leader is always in charge and in front.
Hope this helps you. If you claim leader things will fall into place.
Good luck and let me know how it works out for you and your dog. | 
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