Book Image

Mastering OpenVPN

By : Jan Just Keijser, Eric F Crist
Book Image

Mastering OpenVPN

By: Jan Just Keijser, Eric F Crist

Overview of this book

Security on the internet is increasingly vital to both businesses and individuals. Encrypting network traffic using Virtual Private Networks is one method to enhance security. The internet, corporate, and “free internet” networks grow more hostile every day. OpenVPN, the most widely used open source VPN package, allows you to create a secure network across these systems, keeping your private data secure. The main advantage of using OpenVPN is its portability, which allows it to be embedded into several systems. This book is an advanced guide that will help you build secure Virtual Private Networks using OpenVPN. You will begin your journey with an exploration of OpenVPN, while discussing its modes of operation, its clients, its secret keys, and their format types. You will explore PKI: its setting up and working, PAM authentication, and MTU troubleshooting. Next, client-server mode is discussed, the most commonly used deployment model, and you will learn about the two modes of operation using "tun" and "tap" devices. The book then progresses to more advanced concepts, such as deployment scenarios in tun devices which will include integration with back-end authentication, and securing your OpenVPN server using iptables, scripting, plugins, and using OpenVPN on mobile devices and networks. Finally, you will discover the strengths and weaknesses of the current OpenVPN implementation, understand the future directions of OpenVPN, and delve into the troubleshooting techniques for OpenVPN. By the end of the book, you will be able to build secure private networks across the internet and hostile networks with confidence.
Table of Contents (17 chapters)
Mastering OpenVPN
About the Authors
About the Reviewers

Current weaknesses

There are notable weaknesses in the current version of OpenVPN. First, the entire application is written as a single, monolithic application. The same binary that is used for client connections is also used as the server instance. This isn't too much of a problem, but there is no modularization of code, so all of the logic needs to be handled regardless of the context in which the application is executed.

Working through the monolithic design woes, developers will have an easier time implementing features such as IPv6, additional compression algorithms, and so on. Also, changes to improve the network stack need to be updated in many places within the code, rather than a single library or component. This is the reason the IPv6 and IPv4 stacks are handled separately today.

Scaling at gigabit speeds and above

Typically, on modern hardware, OpenVPN is able to support a couple of hundred client connections before kernel limitations reduce performance to unfavorable levels. This...