Yes the boxer dog breed is a pretty smart dog and is very easy to train as well.
Boxer dogs make good dogs for protection of your family and surroundings because boxers will bark when necessary to ward off any potential threats.
The boxer dog is a pretty smart and intelligent, high-energy, playful dog breed but can be aggressive in certain situations.
If the boxer needs to defend itself or defend against threats of their family then they will attack.
Also if you tease the boxer dog or agitate the boxer dog breed then it could turn aggressive towards it's owners and then cause severe injury or death.
However if you train the dog properly and do not agitate or be mean to the dog or tease the boxer dog breed in anyway and show your love for the boxer dog breed then they make good family pets and are pretty protective.