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

Blocking incoming traffic


One of the most important tasks for a Linux system administrator is to control access to network services. At times, it may be better to block all incoming traffic on the server and only allow the required services to connect.

Getting Ready

As we will be using Iptables here as well, no extra package is needed to perform these steps. We just need a user account with super user access. However, this account should preferably not be a root account.

How to do it...

We will configure Iptables to deny everything except the traffic that has been initiated from inside our system (such as web browsers that get web traffic or a download that has already been initiated to update the package or any other software):

  1. As seen in previous examples, the first rule in Iptables will be to allow access to localhost data. Run this command in order to allow access:

    iptables -A INPUT -i lo -j ACCEPT
    
  2. The next rule will be to accept all traffic-related to outbound connections. This also includes...