The Minecraft security system Mojang should have created to stop griefers.
- Install the mod.
- The whitelist is enabled by default.
- The first person to join the server is given operator. This person adds players to the whitelist.
- All players who join subsequently are put into spectator mode. They can't do anything to your server.
- When you whitelist a player, they are moved from spectator mode to the default game mode of your server.