Book Image

Practical Linux Security Cookbook - Second Edition

By : Tajinder Kalsi
Book Image

Practical Linux Security Cookbook - Second Edition

By: Tajinder Kalsi

Overview of this book

Over the last few years, system security has gained a lot of momentum and software professionals are focusing heavily on it. Linux is often treated as a highly secure operating system. However, the reality is that Linux has its share of security ?aws, and these security ?aws allow attackers to get into your system and modify or even destroy your important data. But there’s no need to panic, since there are various mechanisms by which these ?aws can be removed, and this book will help you learn about different types of Linux security to create a more secure Linux system. With a step-by-step recipe approach, the book starts by introducing you to various threats to Linux systems. Then, this book will walk you through customizing the Linux kernel and securing local files. Next, you will move on to managing user authentication both locally and remotely and mitigating network attacks. Later, you will learn about application security and kernel vulnerabilities. You will also learn about patching Bash vulnerability, packet filtering, handling incidents, and monitoring system logs. Finally, you will learn about auditing using system services and performing vulnerability scanning on Linux. By the end of this book, you will be able to secure your Linux systems and create a robust environment.
Table of Contents (20 chapters)
Title Page
Copyright and Credits
Contributors
Packt Upsell
Preface
Index

Implementing Mandatory Access Control with SELinux


SELinux (short for Security-Enhanced Linux), is a flexible Mandatory Access Control (MAC) devised to overcome the limitations of standard ugo/rwx permissions and ACLs.

Getting ready

In most Linux distributions, such as CentOS and Redhat, SELinux is by default incorporated in the kernel. However, if we are working on any other distribution, such as Debian, we may have to install and configure SELinux on the system:

  1. First, we have to get the basic set of SELinux utilities and default policies by running the following command:
  1. Once the installation has completed, run the following command to configure GRUB and PAM, and to create /autorelabel:

After this, you have to reboot the system to label the filesystems on boot.

  1. After reboot, when the system starts, you may get the following warning:

Now, we have a working SELinux system.

How to do it...

Once we have a working SELinux system, we can choose how to use it:

  1. SELinux can operate in two different ways...