Book Image

Openswan: Building and Integrating Virtual Private Networks

By : Ken Bantoft, Paul Wouters
Book Image

Openswan: Building and Integrating Virtual Private Networks

By: Ken Bantoft, Paul Wouters

Overview of this book

<p>With the widespread use of wireless and the integration of VPN capabilities in most modern laptops, PDA's and mobile phones, there is a growing desire for encrypting more and more communications to prevent eavesdropping. Can you trust the coffee shop's wireless network? Is your neighbor watching your wireless? Or are your competitors perhaps engaged in industrial espionage? Do you need to send information back to your office while on the road or on board a ship? Or do you just want to securely access your MP3's at home? IPsec is the industry standard for encrypted communication, and Openswan is the de-facto implementation of IPsec for Linux.</p> <p>Whether you are just connecting your home DSL connection with your laptop when you're on the road to access your files at home, or you are building an industry size, military strength VPN infrastructure for a medium to very large organization, this book will assist you in setting up Openswan to suit those needs.</p> <p>The topics discussed range from designing, to building, to configuring Openswan as the VPN gateway to deploy IPsec using Openswan. It not only for Linux clients, but also the more commonly used Operating Systems such as Microsoft Windows and MacOSX. Furthermore it discusses common interoperability examples for third party vendors, such as Cisco, Checkpoint, Netscreen and other common IPsec vendors.</p> <p>The authors bring you first hand information, as they are the official developers of the Openswan code. They have included the latest developments and upcoming issues. With experience in answering questions on a daily basis on the mailing lists since the creation of Openswan, the authors are by far the most experienced in a wide range of successful and not so successful uses of Openswan by people worldwide.</p>
Table of Contents (22 chapters)
Building and Integrating Virtual Private Networks with Openswan
Credits
About the Authors
Acknowledgements
About the Reviewers
Preface

The Rest of the Network


Now we have a method for determining what is a local directly reachable host, and what is not directly reachable. We only need one last piece of information. If we cannot communicate to a host directly, because it is not in our local subnet, where do we send packets for that host to? We send it to a special host called the gateway. A host can have different gateways it uses for different remote subnets, and usually a host also has one gateway that it uses for all the unspecified subnets. This gateway is called the 'default gateway'. Obviously, this gateway must be in the local subnet, or we would need a gateway to reach the gateway! Since a gateway is also part of the remote LAN in the remote subnet, you can already deduce that such a gateway machine is in two different subnets, and that it will have two different IP address for that one host. Since an IP address is therefore no longer something that we can unique identify a host with, we need another qualifier to denote a host. This is called the Autonomous System number (AS). Only hosts that need to make dynamic routing decisions tend to get an AS assignment.