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

Using chown to change ownership of files and directories


File ownership is fundamental in Linux. As every file is associated with an owner and a group, we can change the owner of a file or directory using the chown command.

How to do it...

To understand the use of chown, let's follow these steps:

  1. To understand the use of the chown command, let's create a file named file1.txt and a user named user1:

The previous command for changing password information is optional. You can ignore it if you want to.

  1. Now, let's check the current owner of file1.txt.

We can see that the current owner for both the files is root and it belongs to the root group.

  1. Let's change the ownership of file1.txt to user1:

As seen here, the owner of file1.txt has now changed to user1.

  1. If we want to change the group of a file, we can do that also using chown:
  1. We can change both the owner and group of a file in single command as shown here:

We can see that the owner and group of file2.txt have changed.

  1. If we wish to recursively change...