How do stop my pug from barking at everything?

It has gotten out of hand! He never barked at strangers when he was a puppy but ever since he got older (he is 2 years now), he barks at strangers and cars passing by. I'm always embarrassed to take him out for a walk or take him anywhere.

I have 2 other pugs, a 1 year old female and a male puppy. The puppy is their baby. They had a little of 6 and we kept one of the puppies. Anyways, they are both good with strangers, female does barks sometimes but not excessively barking like the adult male. Like when he hears someone outside the door of our house, he will bark non stop and we tell him to stop but he wont. He also shows some kind of aggression. When I take him outside in the front yard, I have him on a leash and we will just walk bark and forth in the sidewalk and whenever he sees a car, he will bark and pull on the leash. I would then pull the leash back and tell him, "NO! No barking!" and he still won't stop. He will just keep pulling the leash and bark. I would then have to carry him back inside the house and he will try to let loose and still bark. He's pretty strong. I'm scared because he's the only pug I know that does that. All the other pugs lets strangers pet them without a problem but mine will just "attack"