Good article that directly applies to Linux but is a sort of tutorial for securing any system that’s exposed to the web.
http://techrepublic.com.com/5100-10877-5987648.html?tag=nl.e550
Which makes me think about five years from now when TechRepublic decides to go out of business, change its archiving methods or decides that it will dump this article. A world of links just disappear everyday.