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


Due to the ease of scripting, the OpenVPN plugin interface is a relatively underutilized tool available to OpenVPN server administrators. OpenVPN, by default, ships with a pair of plugins, one for PAM authentication and another for executing --down scripts with root privileges, regardless of whether the administrator de-escalates privileges.


It's a good idea to drop privileges within OpenVPN, and the down-root plugin allows you to do that. Applications like firewalls require escalated privileges to add and remove firewall rules. By utilizing the down-root plugin, an administrator can provide new firewall rules upon a client connection as well as the ability for the removal of those rules once the client disconnects.

A usage scenario could be a single OpenVPN instance that supports an entire company's staff. Administrative and office staff would not generally need access to lights-out management interfaces and other such systems on a company network. With the addition of firewall...