Chapter 11 Firewall
Figure 131 Block VPN to VPN Traffic by Default Example
11.4Security Considerations
"Incorrectly configuring the firewall may block valid access or introduce security risks to the ZyWALL 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:
1Does 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?
2Is 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?
3Does 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.
4Does this rule conflict with any existing rules?
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