ZyXEL Communications Internet Security Appliance ZyWALL5UTM 4.0 User Manual page 211

ZyWALL 5/35/70 Series User's Guide
• WLAN to WAN
By default, the ZyWALL's stateful packet inspection drops packets traveling in the following
directions:
• WAN to LAN
• WAN to WAN/ZyWALL
This prevents computers on the WAN from using the ZyWALL as a gateway to
communicate with other computers on the WAN and/or managing the ZyWALL.
• WAN to WLAN
This drops any packets travelling from the WAN to the WLAN and creates a log.
• DMZ to LAN
• DMZ to DMZ/ZyWALL
This prevents computers on the DMZ from communicating between networks or subnets
connected to the DMZ interface and/or managing the ZyWALL.
• DMZ to WLAN
• WLAN to LAN
• WLAN to DMZ
• WLAN to WLAN/ZyWALL
This prevents computers on the WLAN from communicating between networks or
subnets connected to the WLAN interface and/or managing the ZyWALL.
You may define additional rules and sets or modify existing ones but please exercise extreme
caution in doing so.
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.
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 ZyWALL's default rules.
211 Chapter 11 Firewall Screens