Introduction to Filtering

Example:

~12-80

This filter pattern will match if

the

packet

 

 

information starting at the 12th octet does not

 

 

equal the 80 of the filter pattern.

 

 

( ) brackets Used in pattern filters to separate portions of filter patterns

for

specific

operators.

 

 

 

Example: 12-80&(14-2414-32) This filter pattern will be checked in two operations. First the section in brackets will be checked and then the results of the first check will be used in the second check using the first portion of the filter pattern. If the packet information starting at the 14th octet equals 24 or 32, and the information at the 12th octet equals 80, the filter pattern will match.

Popular Filters

Shown here are some of the more commonly used pattern filters.

Bridge

Bridge pattern filters are applied to Ethernet frames that are bridged only. When the router is operating as a router, all routed frames will be unaffected by the bridge pattern filters.

IP & Related Traffic

 

IP & Related Traffic

Forward only

 

~(12-080012-0806)

Filter

 

(12-080012-0806)

Novell IPX Frames

 

Novell IPX Frames

EthernetII

 

(12-8137)

802.3 RAW

 

(14-FFFF)

802.2

 

(14-E0E0)

802.2 LLC

 

(14-AAAA&20-8137)

NetBIOS &NetBEUI (Windows For Workgroups)

NetBIOS & NetBEUI (Windows For Workgroups)

Filter

(14-F0F0)

Forward only

~(14-F0F0)

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Perle Systems 1700 manual Popular Filters, Bridge, IP & Related Traffic, Novell IPX Frames