This is a huge issue with many pups and can be very difficult and hazardous if they are not trained properly. I never had much of an issue with mine until four yrs ago when our little Ruby came into our lives. She riles up the gang and than even thou they knew better they would try to go out the door every chance they got. It became very frustrating after a while. They were trained to go in the house when told so it was only a very short trip out but still just as frustrating. I had had enough so after almost two years of intense training at the front door and them learning the new command (back) before everyone, including Ruby would no longer go out of the door when its opened. I could stand there with it hanging open and they will not leave the house.
They were also taught to be on there spot when they hear a knock at the door. They all have to be sitting behind the divider that separated the hard wood from the carpeted area in the entryway before we open the door. They can bark as much as they want but they don't move past that spot. All we need to say is "back" and they move back away from the door and sit. Of course Ms. Ruby has to test her limits every so often, but she quickly learns that mamma don't paly that. LOL and sits where she is suppose to be. Yay... success !
The first thing and most important thing that you need to do is to teach your pup his
name and the
come command !! (you can find a quick and easy way of doing this on my web site)
www.dawnsyorkies.weebly.com/training-tips
Once you have accomplished those two things you can than move onto the
sit and stay or the back commands. Which will help when it comes to the door issue.
You may also want to try the leash training method to help train your pup. I an be helpful when teaching him his boundaries. The front door being one of them.