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

Aggressive Mode


Aggressive mode support, which was always part of Openswan 1, has now also been added to Openswan 2. However, the code is entirely different. One of the problems of aggressive mode is that to save that extra round of negotiation from Main Mode, you need to do a lot of expensive Diffie Hellman computing upon sending and receiving the first packet. However, that opens up the possibility of a trivial denial of service attack, by simply sending bogus aggressive mode packets.

Another side effect of aggressive mode is that you must get the IKE and ESP parameters right in your first proposal, since there is no additional room to negotiate. It has to be precisely right after the first packet exchange. The handling of the CPU-intensive tasks has been split off into a separate process called crypto_helper. Pluto can be told how many helper processes to start using the --nhelpers argument. You can also specify nhelpers= in the config setup section of the ipsec.conf file. A value of...