I had my internal monitoring system on a network I managed set up with port knocking. It ended up being more hassle than I thought it was worth, as it wasn't a

I had my internal monitoring system on a network I managed set up with port knocking. It ended up being more hassle than I thought it was worth, as it wasn't a box that was getting attacked much anyway. It's really pretty easy to set up with iptables in Linux. http://www.debian-administration.org/articles/268 http://www.debian-administration.org/articles/268