ZyXEL Communications Wireless Gateway Series 24.1 About Filtering, Filter and Firewall Configuration, Figure 24-1Outgoing Packet Filtering Process

ZyAIR Wireless Gateway Series User’s Guide

Chapter 24

Filter and Firewall ConfigurationThis chapter shows you how to create and apply filters and setup firewall.

24.1 About Filtering

Your ZyAIR uses filters to decide whether or not 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 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 Ethernet side. Call filtering is used to determine if a packet should be allowed to trigger a call.

Outgoing packets must undergo data filtering before they encounter call filtering. Call filters are divided into two groups, the built-in call filters and user-defined call filters. Your ZyAIR has built-in call filters that prevent administrative, for example, RIP packets from triggering calls. These filters are always enabled and not accessible to you. Your ZyAIR applies the built-in filters first and then the user-defined call filters, if applicable, as shown next.

Call Filtering

No

Active Data

No

Built-in

match

User-defined

No

Outgoing

Data

match

default

Call Filters

match

Initiate call

Packet

Filtering

Call Filters

(if applicable)

if line not up

Send packet

and reset

Match

Match

Match

Idle Timer

Drop

Drop packet

Drop packet

packet

if line not up

if line not up

Or

Or

Send packet

Send packet

but do not reset

but do not reset

Idle Timer

Idle Timer

Figure 24-1 Outgoing Packet Filtering Process

Filter and Firewall Configuration 24-1