Generic Filters; Creating Filters Overview; Creating Filters Using Command Line Interface - 3Com OfficeConnect Remote 812 Cli User's Manual

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HAPTER ANUAL

Generic Filters

Creating Filters
Overview
Creating Filters Using
Command Line
Interface
S
ETUP
IPX-SAP Controls the content of Service Advertising Protocol (SAP) packets that are sent
out or received on specific ports. The IPX-SAP filter rules allow filtering on service
type, server name, network address, node address, and socket number fields of
the service entry. The forwarding process uses the filter information to prevent
the service information from being included in the SAP packet.
IPX-RIP Controls the content IPX RIP packets that are sent out or received on specific
ports. The IPX RIP filtering process filters addresses from the RIP packet upon
transmission, and does not enter routes into the routing table upon receipt.
Generic filters are protocol-independent and are specified by byte and offset
values in a packet. Packets are filtered by comparing each packet's offset value and
byte information with the values that you define in the filter. The router will accept
or reject the packet based on the result.
Creating generic filters can be a complex task. Only experienced users should
employ generic filters, and strictly in cases where data and advertising filters
cannot provide the filtering capabilities that you require.
Filters can be set using either the CLI or the OCR 812 Manager.
The more flexible way of setting filters is through the Command Line Interface
(CLI). Both data and advertisement filters can be set using CLI. For more
information on accessing CLI, see
the OfficeConnect Remote
Data Filters can be set using the HTML Manager (the OCR 812 Manager). Data
filters are used to remove packets from the normal flow of data traffic. They can
be applied to IP, IPX, and/or Bridge traffic. Advertisement filters are used to restrict
information in outgoing or incoming advertisement packets, i.e. IP RIP, IPX RIP, and
IPX SAP packets.
Before creating a filter file, you should carefully identify the information you want
to filter. Decide if you want a filter that discards packets (such as reject all IP
packets whose IP source address is 192.168.200.50) or accept only a subset of
packets (such as accept only bridged packets if the destination MAC address is
002069000001 or 002069000002). Also determine where you want to place the
filter. For example, figure out if you want to apply the filter to packets coming into
the Ethernet port, to packets going out the WAN (ATM) port, or to packets coming
from a specific VC/remote site.
The first step in creating a filter on the OCR 812 is to create a file using a text
editor on a workstation. The file will contain filters defined in the OCR 812 filter
syntax (described below). File names should be short and descriptive, such as IP.FLT.
The next step is to use TFTP (Trivial File Transfer Protocol) to copy the filter file from
the workstation to the OCR 812.
You then use CLI commands to add the filter file to the list of filters and apply the
filter to the appropriate interface or VC / remote site profile.
Chapter 1, Establishing Communications with
812.