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
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Routing


As stated before, the main use case for point-to-point style networks is to connect two remote networks over a secure tunnel. In the previous example, the secure tunnel was established, but no network routes were added.

For the next example, consider the following network layout:

The client-side network 192.168.4.0/24 (with netmask 255.255.255.0) needs to be routed over the VPN tunnel to the server.

On the listening end (server), we start:

[root@server] # openvpn \
    --ifconfig 10.200.0.1 10.200.0.2 \
    --dev tun \
    --secret secret.key 0\
    --route 192.168.4.0 255.255.255.0 \
    --daemon --log /var/log/movpn-02-server.log

On the client side, the code is as follows:

[root@client] # openvpn \
    --ifconfig 10.200.0.2 10.200.0.1 \
    --dev tun \
    --secret secret.key 1\
    --remote openvpnserver.example.com \
    --daemon --log /var/log/movpn-02-client.log

On the server side, a route statement was added to tell OpenVPN that the network 192.168.4.0/24 is found at the other...