Book Image

Practical Linux Security Cookbook

By : Michael A Lindner, Tajinder Kalsi
Book Image

Practical Linux Security Cookbook

By: Michael A Lindner, Tajinder Kalsi

Overview of this book

With the growing popularity of Linux, more and more administrators have started moving to the system to create networks or servers for any task. This also makes Linux the first choice for any attacker now. Due to the lack of information about security-related attacks, administrators now face issues in dealing with these attackers as quickly as possible. Learning about the different types of Linux security will help create a more secure Linux system. Whether you are new to Linux administration or experienced, this book will provide you with the skills to make systems more secure. With lots of step-by-step recipes, the book starts by introducing you to various threats to Linux systems. You then get to walk through customizing the Linux kernel and securing local files. Next you will move on to manage user authentication locally and remotely and also mitigate network attacks. Finally, you will learn to patch bash vulnerability and monitor system logs for security. With several screenshots in each example, the book will supply a great learning experience and help you create more secure Linux systems.
Table of Contents (17 chapters)
Practical Linux Security Cookbook
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Limiting the login capabilities of users


A major role of a system administrator is to configure and manage users and groups on a Linux system. It also involves the task of checking the login capabilities of all users.

Getting ready

All the steps given below have been tried on an Ubuntu system; however, you can also follow these on any other Linux distribution.

How to do it...

Here we will discuss how the login capabilities of users can be restricted on a Linux system:

  1. We can restrict the access of a user account by changing the login shell of the account to a special value in the /etc/passwd file. Let's check the details of an account, sslh as an example, in the /etc/passwd file, as shown:

    cat /etc/passwd | grep sslh
    
  2. In the preceding details, the final value for the sslh account is set to /bin/false. If we now try to log in to sslh user as root, we see that we are not able to do so:

    su sslh
    
  3. So now, if we change the shell of the user account we wish to restrict, we can do so as shown:

  4. Another way...