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

Remote server/host access using SSH


Secure Shell (SSH) is a protocol that is used to log onto remote systems securely and is the most commonly used method for accessing remote Linux systems.

Getting ready

To see how to use SSH, you need two Ubuntu systems. One will be used as the server and the other as the client.

How to do it...

To use SSH, you can use freely available software called OpenSSH. Once the software is installed, it can be used by the ssh command. We will look at how to use this tool in detail:

  1. If OpenSSH server is not already installed, it can be installed using the following command:
sudo apt-get install openssh-server

  1. Next, we need to install the client version of the software:
sudo apt-get install openssh-client

  1. For the latest versions, the SSH service starts running as soon as the software is installed. If it is not running by default, we can start the service by using the command:
sudo service ssh start

  1. Now, to log in to the server from any other system using SSH, you can use the...