Chapter 1, Introduction to Nmap, reviews the history of Nmap, what the tool does, when it will be used, how the product evolved, and how to install Nmap on Windows, Linux, and OS X.

Chapter 2, Network Fundamentals, is about how networks work and why a port scanner is important. It overviews TCP, UDP, port scanning, common ports, and service banners.

Chapter 3, Nmap Basics, covers how to run basic or normal Nmap scans without complex flags.

Chapter 4, Advanced Nmap Scans, is about the advanced flags in Nmap that can designate different types of scans.

Chapter 5, Performance Optimization, is about how to optimize timing, parallelism, and so on, in Nmap in order to complete scans efficiently.

Chapter 6, Introduction to the Nmap Scripting Engine, is about the Nmap scripting engine—what it is, how it works, what programming language it uses, and popular Nmap scripts to use.

Chapter 7, Writing Nmap Scripts, teaches the reader how to create a basic Nmap script in Lua.

Chapter 8, Additional Nmap Tools, covers the other tools that come with the Nmap suite—Nrack, Nping, and Ncat.

Chapter 9, Vulnerability Assessments and Tools, explains the relationships between Nmap and other tools commonly used in professional vulnerability assessments.

Chapter 10, Penetration Testing with Metasploit, is about the interaction of Nmap with penetration testing tools such as Metasploit.

In order to follow along with this book, you need to have a working computer running either Windows, Linux, or Mac OS X. We'll be installing Nmap and VirtualBox as part of running through this book; these are two free pieces of software that can help us run network scans. Additionally, an Internet or local network connection is valuable for trying out scans.

This book is aimed at beginners who have experience as a system administrator or of network engineering, and wish to get started with Nmap. Advanced users can use this book as a reference, or to understand when certain key aspects of the software should be used.

The style and approach of this book is like an easy-to-follow guide full of real-world examples that demonstrate how and when to use different aspects of the Nmap suite. Clear and concise writing makes this introductory-level book an ideal guide to start with. Each topic covers examples from the real world, enabling the reader to easily progress from an Nmap beginner to an advanced user.

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "If you want to make Nmap less verbose than normal, you can also use the --reduce-verbosity flag."

A block of code is set as follows:

  action = function(host, port)
  local robots = http.get(host, port, "/robots.txt")

  if robots.status == 200 then
    return "robots.txt status 200"
  else
    return "robots.txt status: " .. robots.status
  end
  end

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Once the scan is completed, clicking on Vulnerabilities shows the current list of vulnerabilities detected on the target scope."

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