locking root to a machine

[Beartooth]

	A regular on a private list I follow has written : 

    [...] therein lies the beauty of the newer flavors of *nix.  You
   can lock root (and SU) access to physical machines ONLY, and
   even lock it down to specific logins ONLY on specific machines.

	How would Fedora do that?

	I wouldn't want it any PC on my LAN, because I do 99 44/100% of 
the updating and general administrivia on a couple of them remotely over 
ssh; but it sounds like a good thing to have on any laptop or tablet that 
spends much time on wifi.

-- 
Beartooth Staffwright, Not Quite Clueless Power User
I have precious (very precious!) little idea where up is.