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

Dead Peer Detection


Sometimes a VPN tunnel may die without detection, for example if one of the two peers crashes and reboots. If you add NAT and NAT-T into this picture, it becomes even more complex. If some IPsec tunnel has very low traffic, a NAT device in the middle might decide this connection has gone away, and drop its translation entry for it. Now both peers think the IPsec connection is up, but when one of them tries to send a packet, it finds the VPN has silently vanished.

With unencrypted connections, such connections would simply fail on their first packet, since the remote host would send an ICMP message about the (for the remote end) unknown connection.

With IPsec this becomes harder, as the peer that didn't get rebooted cannot just trust any unencrypted ICMP message from the other end.

With the uniqueid=yes option set, which is the default for Openswan, the rebooted end can establish a new tunnel, and since all tunnels are considered unique, the stable end of this connection...