oilman wrote:To the OP
Carrying
There are safe options for carrying in your situation:
Belly band
Kangaroo carry
Various fanny paks
Remora Holsters
etc
There are also options for keeping a guns safely nearby for example a quick assess safe such as a gun vault.
Answering the Door
Do NOT open the door. Many bad things can and have happened when people open the door. Google The Dartmouth Murders
Install a peephole (although a perp can block a peephole with his hand).
DO let them know someone is home there have been situations where people have not answered or verbally responded to a knock and the person then breaks in assuming no one is home.
A chain is worthless (as others have said)
Residential doors are easily kicked in. You can install long throw deadbolt locks on the doors but it is more secure to also install a reinforced strike plate that the deadbolt goes into.
Stay safe.
Say no to peepholes....peepholes are a very bad idea. As another posted, there are devices that allow someone to see through them. But even if that wasn't the case they're still a very bad idea. They give away your presence at the door making you vulnerable to being shot though the door or having it kicked into you. This is 2016. Camera/intercom systems are inexpensive and allow you to be in the best location for defense.