UsernameIpLock

This plugin locks a username to an IP address. It automatically creates the lock when a player joins for the first time. An IP address can have multiple usernames, but a username can only be linked to one IP address. It is designed specifically for VLAN/LAN based offline servers, where someone could otherwise change their username to take over another player’s session. To edit the links, you can edit

/config/iplock.json