What do you mean by "punished"? If you are talking about physical punishment, the dog may feel he has to defend himself against attacks,and that will aggravate the situation.
If not, he may feel he is in charge of the house and not you. Get him neutered and as already advised, use the "No Free Lunch" type training with him.
I also do not advise grabbing dogs by the collar - better to put a leash on him.
Here is a link that should help.
Alpha Boot Camp