Do you have a domain name set up for your server? Are people connecting with a different address or the raw IP? Then this plugin may be for you!
It will kick people connecting with any other address than the one specified in the configuration file with the friendly message "Please log in using <your address>"
This part couldn't really be easier. There's only one configuration node in config.yml:
From 1.2, you can specify multiple addresses:
ip: [example.com, example.net]
In which case the first will be the one in the kick messages.
Running on a port other than the default, such as example.com:25566, is detected and added if necessary