Chapter 8; Filter Configuration; About Filtering - ZyXEL Communications Prestige 642 User Manual

8.1

About Filtering

Your Prestige uses filters to decide whether or not to allow passage of a packet. Data filters are divided into
incoming and outgoing filters, depending on the direction of the packet relative to a port. These filters are
further subdivided into device and protocol filters, which are discussed later.
The following sections describe how to configure filter sets.
The Filter Structure of the Prestige
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 Prestige 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.
Three sets of factory default filter rules have been configured in Menu 21 to prevent NetBIOS traffic from
triggering calls and to prevent incoming telnetting. A summary of their filter rules is shown in the figures
that follow and also see section 8.4 for an example.
The following diagram illustrates the logic flow when executing a filter rule.

Filter Configuration

Prestige 642 ADSL Internet Access Router
Filter Configuration
This chapter shows you how to
create and apply filter(s).

Chapter 8

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