In his book "Secrets of Network Cartography: A Comprehensive Guide to nmap" James Messer assumes no previous knowledge of networking and protocols and quickly explains the basic principles of connection oriented and connectionless protocols with some good analogies.
He quickly moves on through the 3 way handshake and gives examples of how to execute the various types of scan.
Rather than just regurgitating the man pages from NMAP each example combines a graphical representation, the command line to be used and the sample output that is seen on screen. He also explains the advantages and disadvantages of each given scan type and where and when they should/shouldn’t be used.
From here he moves on just as comprehensively through the various ‘ping’ options, OS fingerprinting, host options, port options, logging options, window specific options and timing and tuning options.
The book winds up with a final chapter with several real life scenarios and shows how a network or security administrator can use the seemingly endless features within nmap as an aid to identifying virus outbreaks, to conduct vulnerability assessments, security appliance testing, asset management and firewall auditing. As before these are all shown with the exact command used and the output that is derived from the scan.
Although the document is available in HTML format I found that all the Google ads that went with it were too distracting and so bought the pdf version and am sure glad I did.
If you buy the pdf version you also get a bonus quick reference chart that is a useful as an aide memoir when your trying to remember that obscure option (essential for the CEH exam).
The subject matter does not, and will never lend itself to generating a book that will become a bestseller. However James Messer has taken a complex product and broken it down into its component forms and documented it in a manner that will be useful to noobs and seasoned pro’s alike.
Secrets of Network Cartography: A Comprehensive Guide to nmap book can be found here http://www.networkuptime.com/nmap/index.shtml