Acron - Another rcon

A rewrite of Minecraft rcon that uses WebSocket and JSON to manage the server.

Problems with rcon

[Security] No authorization: All rcon clients are hardcoded with OP level 4 in the Minecraft source code. There are also no permission control, giving any faulty or even malicious client full control over the server.
[Security] Simple authentication: All clients are sharing the same secret, making the secret easy to leak and granting attackers unlimited access to the server.
[Efficiency] Rcon executes commands in a blocking manner. The server joins the main thread and waits for the command to complete before reading more from the client.
[Limit] Rcon does not support pushing server messages to the client. This includes player messages, death messages, server logs, etc. A lot of use cases need such information.
[Limit] Rcon has a fixed command length. Although it is not likely for a command to exceed this limit, it still restricts the use cases of rcon.
[Limit] Rcon commands are hard coded to run at the spawn point of Overworld. It is impossible to execute commands in other positions or dimensions if the command does not support so itself.
[Limit] No Unix domain socket support. Unix domain socket is a great way to do localhost IPC and controlling access using Unix user and groups. However, rcon is forced to listen on a TCP address and port.
[Performance] Minecraft creates a new thread per connection accepted, and it blocks for input. Using a thread pool or async IO is much more performant.
[Security] Rcon does not support TLS. It is just using plain TCP.

[Security] Authentication and Authorization: With Acron, administrators are able to specify unique tokens for each client, and it is also possible to easily define the commands clients are permitted to execute using regex rules.
[Efficiency] Acron uses a command queue to schedule commands. Clients need to specify an ID, and Acron will return the result with the same ID once the command is done. In the meantime, clients can enqueue more commands.
[Limit] Server push: Acron will send player messages, death messages of living entities, player join / leave messages, and server lag warnings to the client. Acron also classifies the messages, so clients do not need to parse them manually.
[Limit] Command length: Acron does not limit command length.
[Limit] Locations and other configurations: Acron clients can specify the world, position, rotation, and name for each command they execute, or they can set a per-connection default.
[Limit] Unix domain socket: Sorry, currently Acron does not support Unix domain socket either. Unix domain sockets will be available in later versions.
[Performance] Acron uses Netty, which is built-in in Minecraft, to performance async IO using thread pools.
[Security] TLS: Although Acron does not support TLS itself, it is using WebSocket, which gives the choice of adding a reverse proxy with TLS support.

Acron is based on:

WebSocket: Instead of designing a Layer 5 protocol, Acron chooses WebSocket to make the implementation of server and client easier. Moreover, WebSocket has a wide range of support compared to plain TCP sockets.
JSON: Although JSON is slow and schema-less, it comes with no addition dependencies as a Minecraft mod because Minecraft depends on GSON internally.
Netty: The WebSocket server is based on Netty because it is built-in in the Minecraft server.
GSON: Acron uses GSON to deserialize / serialize JSON since GSON is also a Minecraft dependency.

Get started by reading:

Licensed under GPL v2.