UsernameIpLock
ModJust a server rule that links a username to an IP address
Type
Mod
Modrinth Downloads
154
Modrinth ID
w2qNOtAI
Last Updated
May 16, 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)Compatibility
Mod Loaders
Game Versions
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