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

1. A working knowledge of basic Linux commands, and of how to navigate through the Linux filesystem.
2. A basic knowledge about tools such as less and grep.
3. Familiarity with command-line editing tools, such as vim or nano.
4. 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 Gigabytes.

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. 

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/MasteringLinuxSecurityandHardening_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: "let's use getfacl to see if we have any Access Control Lists already set on the acl_demo.txt file."

A block of code is set as follows:

   [base]
        name=CentOS-$releasever - Base
        mirrorlist=http://mirrorlist.centos.org/?
        release=$releasever&arch=$basearch&repo=os&infra=$infra
          #baseurl=http://mirror.centos.org/centos/
           $releasever/os/$basearch/
        gpgcheck=1
        gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
        priority=1

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

[donnie@localhost ~]$ tar cJvf new_perm_dir_backup.tar.xz new_perm_dir/ --acls
new_perm_dir/
new_perm_dir/new_file.txt
[donnie@localhost ~]$

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: "Click the Network menu item, and change the Attached to setting from NAT to Bridged Adapter."