UsernameIpLock
I don't know my version or loader
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) |
- Edition: Minecraft Java
- File type: .jar
- Minecraft versions listed: 1.21, 1.21.1, 1.21.2
- How to install: Install the matching mod loader (Forge, Fabric or NeoForge) for your Minecraft version. → Download the .jar. → Put it in the .minecraft/mods folder and launch that loader profile.
- Where to get it: Opens on Modrinth — not every file is mirrored on our own servers.
Install steps are the general flow for this file type — How to install Minecraft Java mods & modpacks walks through it step by step.
- Ships as iplock-1.0.1.jar — drop this file into the mods folder
- Download size: 11 KB
- Download link checked 8 Sept 2026 — working
These come from our own check of the pack file, not from the source page.