Alex, Boeda is a Cane Corso mix, he did what he believes he is supposed to do - protect you from what he perceives is a threat!!! Now, obviously Boeda has a problem figuring out on his own what is a threatening gesture and what is not. How old is he? If he was in a sit and did not show any signs of aggression prior to the ranger extending his arm towards you, then I can say that he is and will be fairly capable of learning what is threatening and what is not. You have to work HARD on control exercises through structured obedience training! Go to a trainer that has experience with mastiffs and work on this!! You should have no problems with this!! Boeda did what he was bred to do, now it is up to you to teach him what is acceptable and what is not!! You will see that in a short while, things like this will not happen again!!! On the plus side, you now know that Boeda will protect you!!!! ;)!!!! Best of luck and please inform your girlfriend and explain to her and have her read about the temperament of Corsos and mastiffs in general! It seems that you have a great dog that was trying to protect its owner. Teaching your dog control through obedience will also increase his confidence because he will be able to "discern friend from foe." This is normal behavior and I'm glad that you caught it in time and a worse incident did not take place!! OBEDIENCE TRAIN!!!!! ALV ps. Have your girlfriend work with him in the obedience and control exercises!!