Book excerpt: Based on the official instructor-led training course of the same name in a self-study product, Cisco® Secure Virtual Private Networks is a comprehensive, results-oriented book designed to give readers the knowledge to plan, administer, and maintain a Virtual Private Network (VPN). Readers are taught to accomplish several specific tasks, including identifying the features, functions, and benefits of Cisco® Secure VPN products; identifying the component technologies implemented in Cisco® Secure VPN products; utilizing commands required to configure and test IPSec in Cisco IOS® software and PIX Firewalls; installing and configuring the Cisco® VPN Client to create a secure tunnel to a Cisco® VPN Concentrator and PIX Firewall; configuring and verifying IPSec in the Cisco® VPN Concentrator, Cisco router, and PIX Firewall; and configuring the Cisco® VPN Concentrator, Cisco® router, and PIX Firewall for interoperability.