Are you running a server and occasionally meet some players you want to get rid of, but they keep coming back using alt accounts and a VPN? Well, now you've got the chance to identify their accounts based on a hardware ID instead of unreliable IPs, skins or behaviour!

What this mod does

This mod is registering an empty argument, making it required on clients if your server has it installed. Players who try to remove it from their modpack can't join your server.
When players join your server, the client calculates a semi-unique hash value based on the player's hardware, which is then stored by the server (<server root>/config/hwid), along with the account UUID.

What this mod doesn't do

Automatically ban people based on hardware IDs
Provide an easy way to find hardware IDs with multiple players in-game

How to use it then?

Check some example scripts further down below, I don't want to bury the following two points under codeblocks as they're quite important to read.

Privacy

While a hardware ID sounds invasive, it's way less confidental information than an IP address. The hardware ID is being calculated on the client using the SHA-256 algorithm, which is irreversible and therefore gives server operators no information on what hardware is being used. The hardware ID can only be used to tell unique hardware configurations apart.

Limitations

Hardware IDs are semi-unique. If players upgrade their computer or replace it entirely, it will change. Players can also have the same hardware ID, if they coincidentally have the same computer, for example a common pre-built. Serial numbers (if existing) are included during the hash calculation to minimize this occurence.
Dedicated troublemakers with knowledge of Java can decompile this mod and create an evil twin, sending a random or specific hardware ID every time they join.

Bash

#!/bin/bash destination_path="/home/minecraftserver/config/hwid" for file in "$destination_path"/* do line_count=$(wc -l <"$file") # Count the number of lines in the file if [ "$line_count" -gt 1 ] # Check if the line count is greater than 1 then echo ""; echo "$(basename "$file")" # Print an empty line and the filename while IFS= read -r line # Read each line from the file do uuid=${line} # Assign the line to the variable 'uuid' response=$(curl -s https://sessionserver.mojang.com/session/minecraft/profile/${uuid}) # Send a request to the Mojang API to get the profile information name=$(echo "$response" | jq -r '.name') # Extract the 'name' field from the API response using jq echo "${uuid} - ${name}" # Print the UUID and the corresponding name done < "$file" # Read from the file fi done

Python 3

import os, json, requests search = "" # Set the search term, eg. username, UUID or parts of either for filename in os.listdir("/home/minecraftserver/config/hwid"): # Iterate over each file in the specified directory with open(f"/home/minecraftserver/config/hwid/{filename}", "r") as file: # Open each file in read mode lines = file.readlines() # Read all lines from the file if len(lines) > 1: # Check if there are more than one line in the file result = "" # Initialize the result string for line in lines: uuid = line.strip() # Get the UUID from each line response = requests.get(f"https://sessionserver.mojang.com/session/minecraft/profile/{uuid}") # Send a GET request to Mojang API to get player profile name = json.loads(response.text)['name'] # Extract the player name from the response result += f"{uuid} - {name}\n" # Append UUID and name to the result string if search in result: # Check if the search string is present in the result print(result) # Print the result