How to make my dog ward off intruders and protect my home when i am around or not?

I have 3 puppy bull mastiffs and 2 pitbulls all within the range of 4-8months old and live in west africa where crime is an everyday thing; armed robberies and burglaries in homes, our policemen are all ****** up security is not guaranteed for life and properties. i need my dogs to be very agressive to ward off intruders can anyone show me how to make my dogs agressive towards intruders.