ZyXEL Communications P-312 manual Security Ramifications, Key Fields For Configuring Rules

P312 Broadband Security Gateway

5.What computers on the LAN are to be affected (if any)?

6.What computers on the Internet will be affected? The more specific, the better. For example, if traffic is being allowed from the Internet to the LAN, it is better to allow only certain machines on the Internet to access the LAN.

16.2.2 Security Ramifications

Once the logic of the rule has been defined, it is critical to consider the security ramifications created by the rule:

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 PCs 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 Rules screen in the Prestige Web Configurator.

16.2.3 Key Fields For Configuring Rules

Action

Should the action be to Block or Forward?

Please note that “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 16.4 for more information on 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?

16-2 Creating Custom Rules