About Filters

Packet filters can increase security and decrease traffic on your network. Filters can be used to limit certain kinds of internetwork communications by permitting or denying the passage of packets through network interfaces. By creating appropriate filters, you can control access to specific hosts, networks, and network services.

IP and IPX packet filters are attached to users, locations, Ethernet interfaces, or network hardwired ports as either input or output filters. SAP filters are attached as output filters only. The Ethernet interface filter is enabled as soon as the name of the input our output filter is set. Input and output are defined relative to the PortMaster interface.

All packets entering a PortMaster through an interface with an input filter are evaluated against the rules in the filter. As soon as a packet matches a rule, the action specified by that rule is taken. If no rules match the specific packet, the packet is denied and is discarded.

For interfaces with output filters attached, all packets exiting the interface are evaluated against the filter rules an only those packets permitted by the filter are allowed to exit the interface.