[luau] Port Knocking

[Taylor Cody L Contractor 502 AOS/PETS]

I thought this was a good article.  Port knocking sounds like a neat and
simple solution to shut down as many ports as possible when they are not in
use.  At least for a small office or a home network.
-Cody

An introduction to how trusted users can manipulate firewall rules to
transmit information across closed ports.
http://www.linuxjournal.com/article.php?sid=6811