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

An overview of PKI

PKI is generally a hierarchical organization of encryption certificate and key pairs. Typically, as used with most websites, the top of the hierarchy is the CA. This is the root of the entire tree, and trust is rooted at this level. If the root is trusted, all the key pairs underlying will also be trusted. From the root-level CA, there can be client certificates, server certificates, sub-CAs, and certificate revocation lists (CRLs). Under each sub-CA, this list of possibilities repeats.

To use a PKI to its full potential, the users and systems need to trust the root CA, and any intermediate CAs in the chain. With most modern web browsers, the browser authors or vendors have vetted and approved a large list of root-level certificate authorities to trust by default. These authorities are generally commercial vendors such as VeriSign, Go Daddy, Comodo, Trend Micro, various government entities, and many others.

Due to this preapproved list for browsers, the vast majority of...