ZyXEL Communications P-661H-61, Manual

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Chapter 13 Firewall
P-661HNU-Fx User’s Guide
200
13.1.2 What You Need to Know
Firewall
The ZyXEL Device’s firewall feature physically separates the LAN/WLAN and the
WAN and acts as a secure gateway for all data passing between the networks.
It is designed to protect against Denial of Service (DoS) attacks when activated.
The ZyXEL Device's purpose is to allow a private Local Area Network (LAN) to be
securely connected to the Internet. The ZyXEL Device 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 ZyXEL Device is installed between the LAN/WLAN 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 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.
ICMP
Internet Control Message Protocol (ICMP) is a message control and error-reporting
protocol between a host server and a gateway to the Internet. ICMP uses Internet
Protocol (IP) datagrams, but the messages are processed by the TCP/IP software
and directly apparent to the application user.
Finding Out More
See Section 13.4 on page 203 for advanced technical information on firewall.