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ZyAIR Wireless Gateway Series User’s Guide
Filter and Firewall Configuration 24-1
Chapter 24
Filter and Firewall Configuration
This 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.
Figure 24-1 Outgoing Packet Filtering Process
Data
Filtering
Outgoing
Packet
Drop
packet
Built-in
default
Call Filters
User-defined
Call Filters
(if applicable)
Initiate call
if line not up
Active Data
Send packet
and reset
Idle Timer
Or Or
Drop packet
if line not up
Drop packet
if line not up
Send packet
but do not reset
Idle Timer
Send packet
but do not reset
Idle Timer
Match MatchMatch
No
match
No
match
No
match
Call Filtering