ZyWALL 2 Series User’s Guide

1.Does this rule stop LAN users from accessing critical resources on the Internet? For example, if IRC is blocked, are there users that require this service?

2.Is it possible to modify the rule to be more specific? For example, if IRC is blocked for all users, will a rule that blocks just certain users be more effective?

3.Does a rule that allows Internet users access to resources on the LAN create a security vulnerability? For example, if FTP ports (TCP 20, 21) are allowed from the Internet to the LAN, Internet users may be able to connect to computers with running FTP servers.

4.Does this rule conflict with any existing rules?

Once these questions have been answered, adding rules is simply a matter of plugging the information into the correct fields in the web configurator screens.

11.3.3Key Fields For Configuring Rules

Action

Should the action be to Block or Forward?

“Block” means the firewall silently discards the packet.
Service

Select the service from the Service scrolling list box. If the service is not listed, it is necessary to first define it. See section 11.8 for more information on predefined services.

Source Address

What is the connection’s source address; is it on the LAN or WAN? Is it a single IP, a range of IPs or a subnet?

Destination Address

What is the connection’s destination address; is it on the LAN or WAN? Is it a single IP, a range of IPs or a subnet?

11.4 Connection Direction Examples

This section describes examples for firewall rules for connections going from LAN to WAN and from WAN to LAN.

LAN to LAN/ZyWALL, WAN and WAN/ZyWALL rules apply to packets coming in on the associated interface (LAN or WAN respectively). LAN to LAN/ZyWALL means policies for LAN-to-ZyWALL (the

Firewall Screens

11-3