NullPass

NullPass is a simple authentication mod for Minecraft servers running NeoForge 1.21.1. It requires installation on the server only: players can join with a normal compatible client and do not need to install the mod themselves.

New players must register an account, while registered players must log in before playing. Until authentication is completed, NullPass prevents the player from moving, chatting, using most commands, interacting with the world, attacking entities, or opening containers.

Passwords are never saved as plain text.

Features

• Server-side-only installation.
• Secure account registration and authentication.
• Salted PBKDF2 password hashing; passwords are not stored in plain text.
• Configurable password length limits.
• /register and /login commands, with optional short aliases.
• /changepassword and optional /logout commands.
• Movement, chat, command, interaction, inventory/container, block-breaking, and attack restrictions before authentication.
• Authentication prompts in chat, the action bar, or a boss bar.
• Configurable prompt repeat interval.
• Configurable registration/login timeout; unauthenticated players are kicked when it expires.
• Configurable limit for incorrect login attempts.
• Incorrect-password feedback with the current attempt count, such as (1/3).
• Optional remembered sessions for reconnecting players.
• Optional same-IP requirement for remembered sessions.
• Customizable messages with legacy Minecraft color codes (&).
• English and Russian language resources; default configuration messages are Russian.

Why Use NullPass?

NullPass is useful for offline-mode or private Minecraft servers where players need a password-based login layer. It keeps the authentication flow focused and configurable without requiring every player to install an extra mod.

Use it when you want to:

• protect player accounts on an offline-mode server;
• prevent unauthenticated players from interacting with the world;
• enforce a login deadline and limit password-guessing attempts;
• offer a convenient session-resume period after normal reconnects;
• customize all player-facing messages and prompt placement.

Base Syntax

Command	Description
/register <password> <confirmPassword>	Creates an account and authenticates the player.
/login <password>	Authenticates a registered player.
/changepassword <oldPassword> <newPassword>	Changes the password of an authenticated player.
/logout	Ends the current authentication session, if enabled in the configuration.
/reg <password> <confirmPassword>	Short alias for /register, if shortCommands is enabled.
/l <password>	Short alias for /login, if shortCommands is enabled.

Passwords are read as single command arguments, so they cannot contain spaces.

Configuration

NullPass uses the NeoForge common configuration file. After the mod has started once, edit the generated nullpass-common.toml file in your server's config directory, then restart the server to apply changes.

Main Options

Option	Default	Description
shortCommands	true	Enables /reg and /l aliases.
sessionExpireSeconds	60	How long a normal reconnect can resume an authenticated session. Set 0 to disable remembered sessions.
requireSameIpForSession	true	Requires the reconnecting player to use the same IP address for session resume.
messageDisplay	ACTIONBAR	Where the registration/login prompt is shown: CHAT, ACTIONBAR, or BOSSBAR.
messageRepeatSeconds	3	Prompt repeat interval. Set 0 to disable repeated prompts.
allowLogoutCommand	true	Allows players to use /logout.
authenticationTimeoutSeconds	60	Time available to register or log in. Set 0 to disable the timeout.
maxLoginAttempts	3	Maximum incorrect /login attempts before the player is disconnected. Set 0 to disable the limit.
password.minLength	4	Minimum allowed password length.
password.maxLength	32	Maximum allowed password length.

Example

shortCommands = true
sessionExpireSeconds = 60
requireSameIpForSession = true
messageDisplay = "ACTIONBAR"
messageRepeatSeconds = 3
allowLogoutCommand = true
authenticationTimeoutSeconds = 60
maxLoginAttempts = 3

[password]
minLength = 4
maxLength = 32

Messages and Colors

Every player-facing message can be changed under the messages section. NullPass supports legacy color codes using &, for example:

[messages]
login = "&6NullPass &7| &fPlease log in: /login <password>"
wrongPassword = "&6NullPass &7| &cIncorrect password."
authenticationTimeout = "&6NullPass &7| &fYou did not authenticate."
loginAttemptsExceeded = "&6NullPass &7| &fThe maximum number of login attempts has been exceeded."

When maxLoginAttempts is enabled, a wrong-password message automatically receives a gray counter before the final failed attempt:

NullPass | Incorrect password. (1/3)
NullPass | Incorrect password. (2/3)

On the final failed attempt, the player is disconnected with the configured loginAttemptsExceeded message instead.

Installation

1. Install NeoForge for Minecraft 1.21.1 on your server.
2. Place the NullPass JAR in the server's mods directory.
3. Start the server once to generate the configuration file.
4. Edit config/nullpass-common.toml if needed.
5. Restart the server.

Clients do not need NullPass installed.