How hard are the bites? Are we talking "I would draw blood from you if I could", scary bites, or play-biting bites?
How old is your dog and for how long has the behavior been going on? Is there anything specific that triggers it, like grabbing for his collar?
For starters, leave a harness and a drag line on your dog when he is roaming free outside. Just cut the handle off an old leash (so it won't get caught on anything) and leave it clipped on him, so that you can control him without having to get close to him.
Could I suggest that you write one much longer, more detailed post describing what is happening with your dog? We really need many more details to understand your dog's behavior. All of these extremely short posts give very few clues, and I think that's why no one has yet suggested any remedies. Give us a thorough description of 150 words or so, and maybe then we can advise you. Thanks!