UsernameIpLock

Mod

Just a server rule that links a username to an IP address

Type

Mod

Modrinth Downloads

244

Modrinth ID

w2qNOtAI

Last Updated

Jul 30, 2026

Description

IpLock

A server-side Fabric mod that prevents account takeovers on offline-mode Minecraft servers by binding each username to the IP address it first joined from.

How it works

When a player joins for the first time, their username is permanently bound to their IP address. If the same username later connects from a different IP, that IP is immediately banned and the connection is rejected. This makes it effectively impossible to impersonate an existing player from a different machine.

First join — username is bound to the connecting IP, player joins normally.
Same IP — player joins normally.
Different IP — connection is rejected and the new IP is banned.

Data is stored in iplock/bindings.json and iplock/bans.json inside the server's run directory.

Commands

All commands require operator level 3 (admin).

Command Description /iplock list Show all username → IP bindings /iplock bans Show all banned IPs and which username they tried to use /iplock unban <ip> Remove an IP from the ban list /iplock reset <username> Delete a username's IP binding (allows them to re-bind from a new IP)