Increase security by adding a door viewer.
There are different types of door viewers. For narrow smaller areas consider a 160 degree viewer.
For large porches consider a 180-200 degree viewer, with a knocker to add some accent. To begin you will need door viewer, drill, screwdrivers and silicone sealant.
Determine a height that is comfortable for your family.
Mark where you will be mounting the door viewer.
Drill the holes for the mounting screws.
Drill a pilot hole for the door knocker, then drill the actual hole.
Mount the door knocker.
Insert the top mounting screw and finishing washer from inside the door.
Tighten the top and bottom screws of the knocker. Finally insert the door viewer.
Tighten the barrel on the inside. If you are just inserting the door viewer add some silicone sealant and tighten the barrel and you're done.