not aggression from what youre saying, more like excitement. crating is an easy solution when you know when someone is coming over, but as you seen first hand it doesnt teach your pup how to behave when he is loose and someone comes knocking out of the blue.
leash, train, practice. get a helper, and i assume you are still treat training, so get some of his faves.
your pup needs to already know the concept of down/stays for this to work effectively.
the key is to keep him in a calm state just before someone knocks or rings the bell. a spot for him to stay in far away enough from the door is helpful so he isnt zipping past you when you go to answer the door. but close enough that he sees you and the door. some folks use an adjoining room doorway as the cut off point for the dog. more than one helper is good too, one at the door, one holding the leash to keep him from darting or you hold the leash and the other helper goes to the door to answer.
heres a senerio: place tyson in a down/stay in his spot, him being leashed. [long lead may work better] your helper is already outside and rings the bell or knocks. you say one minute to your arriving guest [the helper] and settle tyson back on his spot [a bed or floor mat works great] if he rose or walked off. if/when you get him settled again you proceed to the door. if he gets up, before you release him, you stop where ever you are at with answering the door and place him back at his spot in a down/stay. staying calm and relaxed is really important here to keep him calm and focused on what you want. you will have to go back and forth probably many times before you get to the door to even open it at first, but with a good food reward he will learn quickly.
i break it down even more, i just get to the door and turn around and go to the dog and release, then praise and treat. repeat just that for the first 2 or 3 sessions. not more than 20 minutes at a time. if the bell or knock is making it too difficult to get him settled, do sessions without it and just walk back and forth to the door. into the 4th session i do all the steps mentioned but add opening and then closing the door [still no one has walked in at this point]. eventually getting to letting the person walk in and the dog waits to be released before he moves and once released for a job well done, he gets a treat. this is a two part reward. one is his good behavior lets the person at the door come in and then he is released once the guest settles and he gets a reward for listening and for behaving so nicely. having the guest ignore tyson until he calms down is also very helpful to him staying calm.
if he gets up while someone is entering, have them go back outside and he gets no treats for leaving his spot without being released. some dogs can move past this training very quickly others take more time so adjust as you need for your dog.
this was very successful for me with forrest as a pup. i dont place him in down/stays anymore and havent for a long time. but he always greets my guest calmly and never runs past me with a open door.
i would suggest all folks/kids living with you, if any do, have them do this training with tyson as well, so he knows this applies for everyone living in the home.
in the end, you will not get stressed out everytime someone is at the door and your visitors will thank you that they dont have a big dog in their face, everytime they come for a visit.
good luck!
