Guidelines For Security Enhancement With Your Firewall; Security Considerations - ZyXEL Communications NR Series User Manual

• 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 Zyxel Device's default rules.

15.7.2 Guidelines For Security Enhancement With Your Firewall

Change the default password through the Web Configurator.
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Think about access control before you connect to the network in any way.
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Limit who can access your router.
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Don't enable any local service (such as telnet or FTP) that you do not use. Any enabled service could
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present a potential security risk. A determined hacker might be able to find creative ways to misuse the
enabled services to access the firewall or the network.
For local services that are enabled, protect against misuse. Protect by configuring the services to
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communicate only with specific peers, and protect by configuring rules to block packets for the services
at specific interfaces.
Protect against IP spoofing by making sure the firewall is active.
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Keep the firewall in a secured (locked) room.
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15.7.3 Security Considerations

Note: Incorrectly configuring the firewall may block valid access or introduce security risks to
the Zyxel Device and your protected network. Use caution when creating or deleting
firewall rules and test your rules after you configure them.
Consider these security ramifications before creating a rule:
Does this rule stop LAN users from accessing critical resources on the Internet? For example, if IRC
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(Internet Relay Chat) is blocked, are there users that require this service?
Is it possible to modify the rule to be more specific? For example, if IRC is blocked for all users, will a rule
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that blocks just certain users be more effective?
Does a rule that allows Internet users access to resources on the LAN create a security vulnerability? For
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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.
Does this rule conflict with any existing rules?
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