I am about to start a Minecraft server which will be cracked,but I've got a problem:

Anyone can join with my OP account the server and stuck at the login where they have to enter the password,but when someone logins to my server says at the chat "Player has joined." and he is shown at the player list while pressing TAB but that player isn't logged in.But if user try to login with my Owner account(Which I believe will occur often) then they'll say "Oh look finally owner is online but why is he ignoring us?" So I want to disable these essentials/bukkit commands until the player login,is there any way?