I wanna have users to sign up via my forums (using XenForo), and when they connect to the server, they will have to activate their account using "/activate <username>" Is there something that can do this?
Not necessarily. Mainly for my Minecraft server, I wanna encourage players to be active on my forums, so they sign up via the forums, and they'll possibly be white-listed, then when they connect, they type a command like "/activate <username>" and they'll be able to play
Players won't be able to play with this plugin till they created a account on the forum. And do the /activate command.
Yeah, so they sign up via the forums which will white-list them, and then in-game they type /activate <username> I wanna again encourage users to use the forums