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

Extra security – hardware tokens, smart cards, and PKCS#11

In this section, we will provide some background information on cryptographic hardware devices. You will learn how to generate a private key on a hardware token, and how to copy the associated X.509 certificate to the token as well. After that, we will discuss how OpenVPN can find and use this certificate/private key pair to establish a VPN connection.

Background information

Starting with Version 2.1, OpenVPN supports two-factor authentication by providing PKCS#11 support. Two-factor authentication is based on the idea that in order to use a system (like a VPN) you need to provide two things:

  • Something you know, for example, a password

  • Something you possess, for example, a smart card or hardware token

PKCS#11 is an industry standard for communicating with smart cards or hardware tokens, and there are both open source and commercial drivers available. The PKCS#11 standard was originally published by RSA Laboratories and is sometimes also...