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

Debugging kernel boot


Sometimes your system might fail to boot due to changes within the kernel. Hence it is important that when creating reports about these failures, all the appropriate information about debugging is included. This will be useful for the kernel team in resolving the issue.

How to do it...

If you are trying to capture error messages that appear during boot, then it is better to boot the kernel with the quiet and splash options removed. This helps you see the messages, if any, that appear on the screen.

To edit boot option parameters, do the following:

  1. Boot the machine.
  2. During the BIOS screen, press the Shift key and hold it down. You should see the GRUB menu after the BIOS loads:
  1. Navigate to the kernel entry you want to boot and press e.
  2. Then remove the quiet and splash keywords (found in the line starting with linux).
  3. Press Ctrl + X to boot.

You can see the error messages, if any, on the screen. Depending on the type of error messages you encounter, there are other boot options...