limit the user

[gpl]

i just want to asked how can i limmit the user who can access the root...
i mean executing (su -)... is there a way to limit them??

i know that sudo is the one.. but what im talking about the command su -
cause we already have a sudo..and thats why the other authorized user can
excecute a command.. that allows to them..

i want to know who's user are trying to log as root...


any suggestions??

ghem