What is it?
Starting with server and client 1.4.0, an anticheat was added to allow servers to verify a player's game files. The server checks the specified files when a client connects, and if any don't match, the client is immediately disconnected. The server will display this in console, with disconnect reason "CRC check failed", and this will also be shown to the client in the chatbox after being disconnected.
How do I use it?
First, upload any files you want the server to verify to your server. You can place them in any folder you want, but creating a folder specifically for them will help keep things clean and organized. In your server config, add a section at the bottom like the example below:
The src attribute is for the file on your server, which is a relative path from your server's main folder.
The path attribute is for the file in the client's game using a relative path from the game's folder.
You can add as many file entries to this as you want.