3Com OfficeConnect Remote 812 manual Applying Filters Using

Applying Filters Using CLI 6-57

	Most importantly, the router does not know which interface an outgoing
	packet came in through. If a potential intruder forges a packet with a false
	source address (in order to appear as a trusted host or network), there is no
	way for an output filter to tell if that packet came in through the wrong
	interface. An input filter, on the other hand, can filter out packets purporting
	to be from networks that are actually connected to a different interface.
VC/Remote Site Filters	You can configure filters for a specific VC / remote site profile that controls access
	to the network for that location. This filter is only applied for the duration of the
	￿remote network connection. As with interface filters, a remote site filter can be
	configured to apply to input or output data traffic. (Note that you can also assign
	filters (input and output) to your VPN tunnel).
Applying Filters Using	You can apply filters to interfaces and/or users using the CLI. If you modify a file,
CLI	you need to re-assign it to make the changes take effect immediately. Otherwise
	the changes will not take effect until the protocol network (IP, IPX, or bridge) that
	the filter affects goes down and comes back up. This occurs when a network is
	disabled, the WAN connection goes down then up, or when the OCR 812 is
	rebooted.
	Do not apply a filter to more than one interface or VC / remote site profile. Also,
	do not apply an input and an output filter to more than one Ethernet interface.
Applying a Filter to an	To configure an input or output filter on an interface, use the following CLI
Interface Using CLI	commands:
	set interface <interface name> input_filter <filter name>
	set interface <interface name> output_filter <filter name>
	Interface name is eth:1 for the Ethernet interface and atm:1 for the ATM
	interface. For example, to apply an input filter to the ethernet interface: set
	interface eth:1 input_filter filter.fil
	When assigning the filter to the Ethernet interface, you must turn off filter access
	by entering the CLI command set interface eth:1 filter_access off.
	For more information about the filter access, refer to the Setting Filter Access
	section below.
	Do not apply a filter to more than one interface or VC / remote site profile. Also,
	do not apply an input and an output filter to more than one Ethernet interface.

Configuring a Filter for a VC/Remote Site Using

CLI

Do not apply a filter to more than one interface or VC/remote site profile.

To configure an input or output filter for a specific user, use the following commands:

set vc <vc or remote site name>input_filter <filter_name> set vc <vc or remote site name>output_filter <filter_name>

For example, to apply an output filter to a user: set vc corpoffice input_filter

filter.fil