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

Disabling username/password logins


One 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 for all users and disabling them if required.

Getting ready

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

 

 

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, user1 as an example, in the /etc/passwd file, as shown here:
  1. In these details, the final value for the user1 account is set to /bin/bash. At present, we can log in from theuser1 account. Now, if we want to change the shell of the user account we wish to restrict, we can do so as shown here:
  1. If we try to log in from user 1 now, we get...