I have a new MC server professionally hosted. I'm using whitelist to limit users that can connect, but I'm wondering what I need to do to make sure that when my players return, their hard-won items and buildings are where they should be and not blown to smithereens or stolen. Your advice appreciated!
Plug-ins that allow users to protect areas
Many, many mods and plug-ins allow users to "own" small or large parts of the server, where they're the only players (besides mods) able to place or break blocks. These can even be set to prevent TNT and creeper explosions from doing their damage to blocks (health bars are still affected, typically).
Seriously. Auto-backup script. There is no excuse for not saving backups.
Actually vetting people before adding them to the whitelist
If you only whitelist people who are referred by existing players, and therefore you actually have a reason to trust them, your chance of getting a troll is significantly reduced. The faster and easier it is to get on your whitelist, the less protection the whitelist provides. Requiring an existing user to sign in (to the server or your website) and request each new user is a strong defense.
I'm sure there are more answers than this, but these are a good start.
If you don't want a plug-in, just use a command block under spawn, and put this into it: /effect @a[m=0,r=36] 4 2 5 true Then type this in chat:/gamerule commandBlockOutput false Then have a hopper clock powering the command block. (A hopper clock is where you put 2 hoppers facing into each other, then a comparator facing away, leading into one redstone that leads to the command block.) The griefers will not be able to break any blocks. Also, use hopper clocks leading to command blocks with this code in them: /clear @a flint_and_steel /clear @a obsidian /clear @a lava_bucket /clear @a tnt /gamemode 0 @a[your name here] NOTE:Each line of code should be in a different command block. As for them still being able to place normal blocks and mess up you server, you can make it so that there is a place where you put your items into an ender chest, then get you inventory totally cleared. Not pretty, but you could make fit it into a story, where you have to get searched or something like that.