How can I apply some kind of privacy film or tint to block out someone from looking in my front door?

We have an oval door and someone keeps coming by our house and is trying to look in our home. I have security cameras catching them doing this. I am not sure what they want, but it's really making my family freak out. I have two little kids that always run to the front door and look out the side windows and see who's at the door. I have some kind of was paper film on the side, but it's not enough.
  36 answers