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

How to read the log files

Debugging a non-working setup can seem like a daunting task at first. Where should you begin? Luckily, OpenVPN provides excellent logging and debugging facilities. However, with increased logging verbosity, it also becomes increasingly difficult to read these log files. The default log level of OpenVPN is 1, but it is recommended that you set the verbosity to 3. This often gives the administrator enough information to detect setup issues, while keeping the performance penalty to a minimum.

Setting the verbosity to 5 or higher is recommended only for debugging purposes, as it will severely affect performance.

Every example in this book so far has included the setting verb 3. First, we will go through both client and server log files for a working setup with this verbosity. It is important to understand, and possibly even store, the log files of a working connection. When trying to find a bug in a non-working setup, it is very useful to compare the log files of the...