ZyXEL Communications P-660HN-F1A, User Manual

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Chapter 10 Firewalls
P-660HN-F1A User’s Guide
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10.5.3 Security Considerations
Note: Incorrectly configuring the firewall may block valid access or introduce security
risks to the P-660HN-F1A 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.
10.5.4 Triangle Route
When the firewall is on, your P-660HN-F1A 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 P-660HN-F1A to protect your LAN
against attacks.
Figure 82 Ideal Firewall Setup
1
2
WAN
LAN