That's what dot1x is for

(That Windows sysadmins treat their work as if it were home, with lashup hacks that fall apart all the time, while Unix sysadmins treat their home as if it were work, with high-end stuff like Kerberos all over the place hugely overspecified for their tiny setups. It's not true of Windows anymore, which is a lot less lashupy now that the Windows 9x line has died, but I certainly thought it was still true of a lot of Unix sysadmins.)