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

Configuring and using TCP Wrappers


Securing a server by restricting access is a critical measure that should never be omitted while setting up a server. Using TCP Wrappers, we can allow only those networks to have access to our server's services that we have been configured and support TCP Wrappers.

Getting ready

For demonstrating the following steps, we are using two systems that are on the same network and can ping to each other successfully. One system will be used as a server and the other will be used as a client.

How to do it...

Linux provides several tools for controlling access to the network services. TCP Wrappers is one among those and adds an additional layer of protection. In the following steps, we will see how to configure TCP Wrappers to define the access for the different hosts:

  1. First, we need to check whether a program supports TCP Wrappers or not. To do so, first, find the path of the program executable by using the which command:
which sshd

Here, we have used the SSH program...