Guidelines For Enhancing Security With Your Firewall; Security Considerations; Triangle Route - ZyXEL Communications P-660HN User Manual

Chapter 9 Firewalls

9.5.2 Guidelines For Enhancing Security With Your Firewall

1 Change the default password via web configurator.
2 Think about access control before you connect to the network in any way.
3 Limit who can access your router.
4 Don't enable any local service (such as telnet or FTP) that you don't use. Any enabled
service could 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.
5 For local services that are enabled, protect against misuse. Protect by configuring the
services to communicate only with specific peers, and protect by configuring rules to
block packets for the services at specific interfaces.
6 Protect against IP spoofing by making sure the firewall is active.
7 Keep the firewall in a secured (locked) room.

9.5.3 Security Considerations

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:
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 entering the
information into the correct fields in the web configurator screens.

9.5.4 Triangle Route

When the firewall is on, your ZyXEL Device acts as a secure gateway between your LAN and
the Internet. In an ideal network topology, all incoming and outgoing network traffic passes
through the ZyXEL Device to protect your LAN against attacks.
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P-660HN-Fx User's Guide