Book excerpt: This volume provides hands-on methodology for designing effective network-level security systems for your corporate intranet or extranet. Using real-world examples and referencing intranet and extranet technology, this guidebook for IT professionals shows how to configure network and security elements such as routers, switches, servers and firewalls to achieve top-notch security. Components of effective security are critically reviewed in detail, including different types of firewalls, such as Packet Filters, Stateful and Application level proxy devices, and encryption schemes, such as DES, RSA, and IPSEC. Secure data transport and data access are also discussed, as well as the use of remote intelligent agents on network devices and servers. The book discusses how to evaluate security options based on requirements such as cost, complexity, and performance, and network and service management issues. It seeks to close the gap between theory and implementation by featuring detailed case studies and an interactive approach with diagrams and configurations.