It's very difficult and even dangerous to make recommendations on aggression over the net.
Your dog's job is to alert you to possible danger, strangers at the door, etc.
It is your job to take control and decide what is or is not a threat.
Right now, your dog is making the decision that EVERYONE is a threat.
The "No Free Lunch" regimen should help him understand that you are alpha. Never punish him for his growling and barking. This may stop the growling, but not the reason for it, and lead him to go directly to a bite instead.
Personally, I would consult a behaviorist who can come to your home, see your dog in action and understand exactly what is going on. Is your dog fearful, aggressive, insecure?
Only by seeing him can that be known and appropriate steps taken.