Chapter 13 Firewall; Introduction - ZyXEL Communications Parental Control Gateway HS100/HS100W User Manual

This chapter gives some background information on firewalls and explains how to get

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
HomeSafe User's Guide
Chapter 13
Firewall
started with the HomeSafe firewall.
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