Ignore bad behavior and do not give in. You can't look at him, give no facial response or speak to him. Say "no" up to 2 times (no more). This is called "extinction". It's a good idea to try to redirect but if doesn't work that is what I have used and also learned in the Behavior Analysis program. If your son gets violent or throws a fit it is best to get this straightened out before he gets too big. Should he become aggressive please look up the "basket hold" so that you can keep him from hurting himself and you. Once he gets big it's more difficult. Also, you can block aggressions now.
The big thing here is to not give any attention for bad behavior. Just the attention is considered positive reinforcement because it will increase the behavior.
Just my opinion... hope it helps... the tough part of parenting.