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

Using IPv6

With OpenVPN 2.3 came solid support for IPv6, both within the OpenVPN tunnel as well as for transit of the tunnel itself. OpenVPN all the way back to 1.x had rudimentary support for IPv6, which was largely rewritten. Overall, inside an OpenVPN tunnel an administrator can choose to support Ethernet (layer 2), IPv4 (layer 3), and IPv6 (layer 3).

The diagram illustrates the logical relationship of the transit network path and the protected network path. Only a single transit method needs to be used, and a single OpenVPN configuration can contain both IPv4 and IPv6 --remote entries. All traffic, regardless of type, will be protected within the tunnel. It is perfectly acceptable to have an all-IPv6 tunnel, using IPv6 for both transit and protected traffic. With additional routing and proxying, it’s even possible to use OpenVPN to aid in IPv6 to IPv4 translation.

Protected IPv6 traffic

Building on the examples from the previous section, we can provide IPv6 addresses to clients and protect...