Chapter 9 Filter Setup Configuration; About Filtering; The Filter Structure Of The Expwave; Figure 9-1 Filter Rule Process - ZyXEL Communications ZyXEL ExpWave 240B User Manual

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Table of Contents

9.1 About Filtering

Your ExpWave uses filters to decide whether to allow passage of a data packet and/or to make a call. There are two

types of filter applications: data filtering and call filtering. Filters are subdivided into device and protocol filters, which

are discussed later.

Data filtering screens the data to determine if the packet should be allowed to pass. Data filters are divided into

incoming and outgoing filters, depending on the direction of the packet relative to a port. Data filtering can be applied

on either the WAN side or the LAN side. For incoming packets, your ExpWave applies data filters. Packets are

processed depending upon whether a match is found. The following sections describe how to configure filter sets.

9.1.1 The Filter Structure of the ExpWave

A filter set consists of one or more filter rules. Usually, you would group related rules, e.g., all the rules for NetBIOS,

into a single set and give it a descriptive name. The ExpWave allows you to configure up to twelve filter sets with six

rules in each set, for a total of 72 filter rules in the system. You cannot mix device filter rules and protocol filter rules

within the same set. You can apply up to four filter sets to a particular port to block multiple types of packets. With

each filter set having up to six rules, you can have a maximum of 24 rules active for a single port. See Figure 9-1 Filter

Rule Process for the logic flow when executing an IP filter.

Filter Setup