Introduction To Zyxel's Firewall; Figure 9-1 Zywall Firewall Application - ZyXEL Communications ZyWALL 5 User Manual

ZyWALL 5 Internet Security Appliance
9.2.3 Stateful Inspection Firewalls
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. See section 9.5 for more information on
Stateful Inspection.
Firewalls, of one type or another, have become an integral part of standard security solutions for
enterprises.
9.3

Introduction to ZyXEL's Firewall

The ZyWALL firewall is a stateful inspection firewall and is designed to protect against Denial of
Service attacks when activated (in SMT menu 21.2 or in the web configurator). The ZyWALL's
purpose is to allow a private Local Area Network (LAN) to be securely connected to the Internet. The
ZyWALL 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 ZyWALL also has packet-filtering
capabilities.
The ZyWALL 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 ZyWALL has one Ethernet WAN port and one Ethernet LAN port, which are used to physically
separate the network into two areas.
The WAN (Wide Area Network) port attaches to the broadband modem (cable or ADSL)
connecting 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" will not be allowed unless the remote host
is authorized to use a specific service.
9-2
Denial of Service Attacks

Figure 9-1 ZyWALL Firewall Application

Firewalls