Whoa.. 2k.. No. Dominance theory is bogus. Dogs and humans have a partnership, there is no 'alpha' or 'boss'. Being rough with a dog only leads to short term fixes and if it IS a fear issue it can make it worse. My dog had a guarding issue with my toddler, no longer is that the case. Instead of punishing her for growling at my child.. I simply removed my child and started positively working with her. It became a GOOD thing to have my daughter around her when she's eating something high value, not negative. Taking a way a dogs fight or flight,or warning system.. aka growl, you can get a dog thats bites WITHOUT a warning. The dog becomes unpredictable.
Start working on the dog right this second. Form a POSITIVE connection with strangers. Strangers are not out to hurt the pooch, instead strangers are awesome things full of rewards, not punishment.
Firstly, what training method do you use? I highly recommend clicker training in a confined area OR on a lead. Clicker training can boost a dogs self confidence and allows the dog to learn problem solving skills.
What motivates your dog? Mine goes nuts over any food and will even work for her kibble. Some dogs work for praise and being loved on. Some dogs are very toy motivated.
Do you have a couple of friends that the dog is wary of you could work with? Start small.. Maybe people the dog already knows but isn't comfy with. Load your clicker, if you use one. Click..treat. Click..treat. click..treat. About 20 times or until the dog begins to react to it. Licking the lips after a click.. Eyes snapping to you after a click.. Ears perking after a click.. Fido is realizing something awesome is coming. Never click WITHOUT treating, but you can treat without clicking. Start with basic commands her already knows. "Sit" :clicker: :treat: "Down" :click: :treat:. The treat is what motivates your dog whether its play or food. Food generally works easiest and most conviently. Foods treats should be tiny.. Think pinky nail size. All clicker training sessions should be no longer than 15 minutes or the dog gets bored. You want it to be a fun game!
Working on the agression. Once the dog understands that the click means they did something right they will start WORKING to get clicks. My dog will do really silly things to get me to click and treat her. Its really cute. Like.. Potty training her was a blast because she'd pee.. I'd click.. and she'd try to pee several more times for clicks.. Or just squat without peeing because she knew I'd click. xD
Anyways... Start with people he knows. Going up to someone gets him a click and treats. After a little while of this you can even add on.. "Go get -insert name-" Like.. Your mother or father or siblings. Someone he's comfy with. Move on to friends he knows.. But its very comfy with. Leash him. Walk up to the person but stop AS SOON AS he shows ANY fear signs. Stop and wait for him to calm down. Click and treat.. Move away. Go back and stop at the same point. Click and treat when he calms down. Do with several times just having the person stand in the same place. As he gets more and more comfy.. Move closer and closer stopping when there are ANY fear signs. Finally, you should be right next to the person with a calm dog. Wait for him to interact with the person.. CLik and treat.

Its a long process, but trust me its so worth it and it leads to a calmer, happier dog that relates people as GOOD things. Heck, even click and allow the OTHER person to offer treats. Make it a joint effort.
For strangers, its the same process but may take a bit longer. Patience and short sessions are the key! Clicker train outside of the aggression as well, theres tons of games out there. =) In my experience, dogs learn so much faster with clicker training. My girl now can get a behavior down pact with just a few clicks and always remember it.
Feisty Fido by Patricia B. McConnellis a good book to check out, also The Cautious Canine by Patricia B. McConnell is pretty awesome.
http://www.youtube.com/watch?v=_wv1uvvqaSw Clicker training.
http://www.positivedogs.co.uk/canine_hu ... action.htm I have an entire list of articles that disprove the dominance theory and how outdated it is. :l