A whitelist turns your server from open to invitation-only. It is the simplest protection there is against random visitors, and it takes two commands.
What to do
- Add yourself first
In the console, run
whitelist add YourUsername. Do this before turning the whitelist on, or you will lock yourself out of your own server. - Add everyone else
whitelist add TheirUsernamefor each player. The name has to be their exact Minecraft username. - Turn it on
Run
whitelist on. From that moment anyone not on the list is refused at the door.
How to confirm it worked
whitelist list prints the names you added. A player who is not on it sees You are not white-listed on this server! when they try to join.
Worth knowing
Operators are not automatically whitelisted. If you op yourself but never add yourself to the list, you get refused like everyone else.