About Filter Rules

Filter rules define the way filters control packet traffic through a local Ethernet port. The packet filtering process analyzes the header information contained in each packet sent or received through a network interface. The header information is evaluated against a set of rules, which allow the packet to pass through the interface (permit) or cause the packet to be discarded (deny).

A packet can contain three sets of rules: IP, IPX, and SAP. Within each set, the rules are numbered starting at one. Newly created packet filters contain zero rules or an empty set of rules.

An empty set of rules is equivalent to the permit rule. If a filter contains one or more rules in the set, any packet not explicitly permitted by a rule is denied at the end of the rule set.

If a single filter rule is selected in the rule list, the rule's configuration will show up in the rule editor. You can edit the rule and click Apply Changes for the changes to be reflected in the rule list. You can click "Cancel Changes" to restore the rule to its configuration as represented in the rule list.