ZyXEL P-324 User Guide - Page 128

Prestige 324 User's Guide Chapter 10 Firewall This chapter gives some background information on firewalls and explains how to get started with the Prestige firewall. 10.1 Introduction What is a Firewall? Originally, the term firewall referred to a construction technique designed to prevent the spread of fire from one room to another. The networking term "firewall" is a system or group of systems that enforces an access-control policy between two networks. It may also be defined as a mechanism used to protect a trusted network from an untrusted network. Of course, firewalls cannot solve every security problem. A firewall is one of the mechanisms used to establish a network security perimeter in support of a network security policy. It should never be the only mechanism or method employed. For a firewall to guard effectively, you must design and deploy it appropriately. This requires integrating the firewall into a broad information-security policy. In addition, specific policies must be implemented within the firewall itself. Stateful Inspection Firewall. Stateful inspection firewalls restrict access by screening data packets against defined access rules. They make access control decisions based on IP address and protocol. They also "inspect" the session data to assure the integrity of the connection and to adapt to dynamic protocols. These firewalls generally provide the best speed and transparency; however, they may lack the granular application level access control or caching that some proxies support. Firewalls, of one type or another, have become an integral part of standard security solutions for enterprises. About the Prestige Firewall The Prestige firewall is a stateful inspection firewall and is designed to protect against Denial of Service attacks when activated (click FIREWALL and then click the Enable Firewall check box). The Prestige's purpose is to allow a private Local Area Network (LAN) to be securely connected to the Internet. The Firewall 10-1