Dog Charmer: Dakota is smart, but the woods distract him

We have a beautiful and smart six-month-old male Rottweiler named Dakota. He is really good with the basics of sit, lay down and stay. We love to go hiking and the goal is to be able to take him off leash. He loves to be out in the woods. How do we get him to be more attentive to us when walking? We need him to come back to us quickly when called and greet other dogs and their owners with manners. He comes now but sometimes we have to go to him and get his attention again. We would like him to respond without us going to him.

Peggy