Excited door greetings are a common behavior that I work with for clients. It is easy for this to become a problematic behavior because the meeting of guests or the act of guarding can be so highly reinforcing for dogs. The keys to adjusting this behavior are coming up with a form of differential reinforcement, or replacement behavior, and overcoming competing reinforcers, or having the reward be more exciting.
To begin we need to figure out what we want the behavior to look like because charging, jumping is not it. Generally, this looks like a dog sitting at a specific spot and waiting to be allowed to say hello to the guests. So first we choose a location that is easy for the dog to identify, such as a dog bed or archway. Then we run them through the behavior of sitting and staying at that spot when they hear a knock or a doorbell.
The biggest factor that people miss on this though is using something exciting enough to compete with a guest. This means experimenting with treats and also practicing under a low stimulus situation. A low stimulus situation would be something like one person that lives in the home leaving to knock repeatedly while going through the above exercise to create a habit and desensitize the pup to the doorbell or knock. As the pup becomes used to the exercise and understands that reward will be coming at another location the drive to charge the door slowly dwindles. To further get the pup to understand that rewards will come when they do the wanted behavior, we will kick the "guest" out if the dog breaks their stay behavior. This will teach the dog that they will not receive the reward of saying hello if they don't stay where they are supposed to.