ZyXEL Communications HS100/HS100W manual Chapter Firewall, Introduction

HomeSafe User’s Guide

Chapter 13

Firewall

This chapter gives some background information on firewalls and explains how to get started with the HomeSafe firewall.

13.1 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 HomeSafe Firewall

The HomeSafe 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 HomeSafe's purpose is to allow a private Local Area Network (LAN) to be securely connected to the Internet. The HomeSafe can be used to prevent theft, destruction and modification of data, as well as log events, which may be important to the security of your network.

The HomeSafe is installed between the LAN and a broadband modem connecting to the Internet. This allows it to act as a secure gateway for all data passing between the Internet and the LAN.

The HomeSafe has one Ethernet WAN port and four Ethernet LAN ports, which are used to physically separate the network into two areas.

The WAN (Wide Area Network) port attaches to the broadband (cable or DSL) modem to the Internet.

The LAN (Local Area Network) port attaches to a network of computers, which needs security from the outside world. These computers will have access to Internet services such as e-mail, FTP and the World Wide Web. However, "inbound access" is not allowed (by default) unless the remote host is authorized to use a specific service.

13.1.1 Guidelines For Enhancing Security With Your Firewall

1.Change the default password via web configurator.

2.Think about access control before you connect to the network in any way, including attaching a modem to the port.

3.Limit who can access your router.

Firewall 13-1