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. 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 performance optimization advice.
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
the Nmap Scripting Engine (NSE), which allows users to write (and
share) simple scripts to automate a wide variety of networking tasks.
My favorite chapter is number 10: Detecting and Subverting
Firewalls and Intrusion Detection Systems. For balance,
that is followed by a chapter on defending against Nmap scans.
Chapter 12 then fully documents the Zenmap multi-platform Nmap GUI and
results viewer. The next two chapters cover output formats and data
files. The final four chapters are reference guides for the whole
family of tools: Nmap, Ndiff, Ncat, and Nping. These are quick
resources for looking up specific command-line options or brief
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.