If your dog is afraid of strangers, then socialize him even heavier in public. Do NOT let him stand between you & the stranger as he feels it is his responsibility to guard you. Let him know you are in control by stepping out in front of him and placing yourself between him and the stranger. Make sure not to make a big deal out of his dislike of strangers but do not ignore any attitude towards them! If he is food motivated then you can try giving treats when he just sits there appropriately in the presence of a stranger. Or, if he will accept them and the stranger will cooperate, then have the stranger give him treats. The period between 1 and 2 years is a tricky time as your dog is coming into himself. Some of the most major changes in personality you will ever see will be between these ages, and by the age of 3 their personality and fears are pretty much cemented.