To get the most out of this book, you don't need much. However, the following things would be quite helpful:

• A working knowledge of basic Linux commands and how to navigate through the Linux filesystem
• A basic knowledge about tools such as less and grep
• Familiarity with command-line editing tools, such as vim or nano
• A basic knowledge of how to control systemd services with systemctl commands

For hardware, you don't need anything fancy. All you need is a machine that's capable of running 64-bit virtual machines. So, you can use any host machine that runs with almost any modern CPU from either Intel or AMD. (The exception to this rule is with Intel Core i3 and Core i5 CPUs. Even though they're 64-bit CPUs, they lack the hardware acceleration that's needed to run 64-bit virtual machines. Ironically, Intel Core 2 CPUs and AMD Opteron CPUs that are much older work just fine.) For memory, I'd recommend at least 8 GB.

You can run any of the three major operating systems on your host machine, because the virtualization software that we'll be using comes in flavors for Windows, macOS, and Linux.

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packtpub.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the Support tab.
3. Click on Code Downloads.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Mastering-Linux-Security-and-Hardening-Second-Edition. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: http://www.packtpub.com/sites/default/files/downloads/9781838981778_ColorImages.pdf.

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Download the installation .iso files for Ubuntu Server 18.04, CentOS 7, and CentOS 8."

A block of code is set as follows:

//Unattended-Upgrade::Automatic-Reboot "false";
  Unattended-Upgrade::Automatic-Reboot "true";

Any command-line input or output is written as follows:

sudo apt update
sudo apt dist-upgrade

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Spend some time perusing the Common Vulnerabilities and Exposures database, and you'll soon see why it's so important to keep your systems updated."