Intended Audience and Organization
This book documents the free Nmap Security Scanner, from port
scanning basics for novices to the types of packet crafting used by
advanced hackers. So it should benefit Nmap users (or potential users)
of all experience levels.
Starting with the basics, this book gives an overview of Nmap by
example in Chapter 1. Then Chapter 2 covers obtaining, compiling and
installing Nmap. Chapters 3 through 5 cover features in the
order you might use them when conducting a penetration test. First
comes host discovery (“ping scanning”), which determines
the available hosts on a network. Next port scanning is
covered in depth. In Chapter 5, all the Nmap scanning techniques are
detailed, with advice and examples. Scanning a large network can take a long time, so
Chapter 6 is full of advice for optimizing the process. Chapter 7
details service and application version detection, in which Nmap
queries ports to determine exactly what is running rather than simply
guessing based on the port number. Chapter 8 covers one of Nmap's
most loved features: remote OS detection. Chapter 9 details one of
Nmap's newest features: the Nmap Scripting Engine. NSE allows users
and developers to easily extend Nmap with new features by writing
simple scripts to be efficiently executed against target machines. My
favorite chapter is number 10: Detecting and Subverting Firewalls and
Intrusion Detection Systems. To be fair, it is followed by a chapter
on defending against Nmap scans. The next two chapters cover output
formats and data files. The final and longest chapter is the Nmap
Reference Guide, the quickest resource for looking up specific Nmap
options.
Scattered throughout the book are detailed instructions for
performing common tasks such as scanning a network for a certain
single open TCP port or detecting wireless access points by scanning
from the wired side. First each problem is described, then an
effective solution is provided. A final discussion section describes
the solution in more depth and may provide alternative solutions and
insights into similar problems.