ZyXEL Communications 662HW Series - Manual (Page 159)

Prestige 662H/HW Series User’s Guide
159 Chapter 14 Firewall Configuration
• WAN to WAN/ Router
This prevents computers on the WAN from using the Prestige as a gateway to
communicate with other computers on the WAN and/or managing the Prestige.
• DMZ to LAN
• DMZ to DMZ/ Router
This prevents computers on the DMZ from communicating between networks or subnets
connected to the DMZ interface and/or managing the Prestige.
You may define additional rules and sets or modify existing ones but please exercise
extreme caution in doing so.
For example, you may create rules to:
• Block certain types of traffic, such as IRC (Internet Relay Chat), from the LAN to the
Internet.
• Allow certain types of traffic, such as Lotus Notes database synchronization, from
specific hosts on the Internet to specific hosts on the LAN.
• Allow everyone except your competitors to access a Web server.
• Restrict use of certain protocols, such as Telnet, to authorized users on the LAN.
These custom rules work by comparing the Source IP address, Destination IP address and IP
protocol type of network traffic to rules set by the administrator. Your customized rules take
precedence and override the Prestige’s default rules.
14.3 Rule Logic Overview
14.3.1 Rule Checklist
State the intent of the rule. For example, “This restricts all IRC access from the LAN to the
Internet.” Or, “This allows a remote Lotus Notes server to synchronize over the Internet to an
inside Notes server.”
1 Is the intent of the rule to forward or block traffic?
Note: If you configure firewall rules without a good understanding of how they
work, you might inadvertently introduce security risks to the firewall and to the
protected network. Make sure you test your rules after you configure them.
Note: Study these points carefully before configuring rules.