Randy, to answer your earlier questions:
No need for any of the tools mentioned in that response to you. Unix and Linux
had it going much earlier. I am surprised this question was even asked here.
Yes, 20 years ago when I got here, there were already running a wide network
of a mix of SGIs, Suns and even Windows, all centrally managed. The switch
the Linux (on the Unix side) was swift in 2000. And the user permissions
are managed by groups, all possible with the good old "yellow pages" ("yp"),
of Linux NIS. Surely you have heard of it.
Individual systems are tied to specific RJ45s through the NIC address, and
they are bootp-ed (PXE) with specific IPs. You need to get to the hardware
to attempt malicious work. It is hard to break its security, but it can be
done. But it is also easily detectable. This system has worked flawlessly
across distributions and versions.