Hook/Module AS player is joining?

Is there any hook/module that can be called when a player is joining? For example, stop them before they actually get into the server? Like bans do, they kick you before you get in.

GM.PlayerConnect
GM.PlayerAuthed

Thanks! So for example to stop all joining I do:

[lua]function GM:PlayerAuthed(ply, sid, uid)
return false
end[/lua]