On many Linux distributions you can simply do the following to find out your flavor:

cat /etc/issue

It will return something like this:
Ubuntu 9.04

There are a number of websites that cater to the Amateur Radio community.
You can start by going to the Linux section on my website: http://w7hd.homelinux.net
I have links to some good sites there.

If you're interested in Propagation studies and would like to participate, goto http://www.propnet.org

If you are having problems with Smoothwall Express 3.0 getting it to forward to an internal address, as I did, you may want to double-check your target machine. My target Linux box was picking up the wireless router and routing through it instead of through the firewall, so it APPEARED not to work. As soon as I turned off the wireless on the target PC it started working through the firewall.

By the way, I picked Smoothwall because it will let me block external addresses. I had...