Nmap From an Ethical Hacker's Point of View
ddonzal notes a new tutorial that introduces Nmap from the viewpoint of an ethical hacker. (Part 1 of 2 parts is up now.) The author is Kirby Tucker, who writes: "After completing this 2 Part Series and having practiced the techniques described, one should not only be able to sit at a 'roundtable' with advanced security professionals and 'hold their own' in a discussion concerning Nmap, but also utilize this great tool in protecting their own network."
"Unlike the for loop, the while loop will always execute at least once. This is because the condition test is checked after the first iteration."
-- Gray Hat Hacking, The Ethical Hacker's Handbook
(Do I have to say more?)