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ZyWALL 2 and ZyWALL 2WE
Creating Custom Rules 16-1
Chapter 16
Creating Custom Rules
This chapter contains instructions for defining both Local Network and Internet rules.
16.1 Introduction to Custom Rules
Firewall rules are grouped based on the direction of travel of packets to which they apply:
• LAN to LAN/ZyWALL • WAN to LAN
• LAN to WAN • WAN to WAN/ZyWALL
By default, the ZyWALL’s stateful packet inspection allows packets traveling in the following directions:
• LAN to LAN/ZyWALL
This allows computers on the LAN to manage the ZyWALL and communicate between networks or
subnets connected to the LAN interface.
• LAN to WAN
By default, the ZyWALL’s stateful packet inspection blocks 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.
You may define additional rules and sets or modify existing ones but please exercise extreme caution in
doing so.
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.