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

User authentication and logging


One of the major parts of user authentication is to monitor the users of the system. There are various ways to keep a track of all the successful and failed login attempts made by a user in Linux.

Getting ready

Linux system maintains a log of all loginattempts by different accounts in the system. These logs are all located at /var/log/:

 

How to do it...

Linux has many ways to help an administrator to view the logs, both through graphical and command-line methods:

  1. If we want to check the incorrect login attempts for a particular user, like root for instance, we can do so by using this command:
lastb root

 

 

 

 

  1. To see the log using the Terminal, we use the dmesg command. This command displays the buffer of the Linux kernel's message stored in memory, as shown here:
  1. If we wish to filter the preceding output to show only the logs related to USB devices, we can do so by using grep:
  1. Instead of viewing all the logs, if we wish to view only the 10 most recent logs in a particular...