Actually if you searched about the breed and read, you are going to see that gsd is naturally protective. However, you have to socialize your dog to prevent inappropriate aggression toward strangers. I assume you just got a puppy, so let him grow up, of course with traininf and socialization. Do obedience training, the earlier the better. Spend lotsssss of time with him, take him wherever you can take with you. It makes him to adopt new environments easily. I hope this helps, you can't schutzund train a dog , unless he is fully obedience trained. If you want, after one year of age, you can make him train for protection work with a good trainer. Schutzund is a sport, but what I really understand is you are more into protection work. Good luck