Netopia Firmware 4000-Series - Manual (Page 252)

10-28 Firmware User Guide
Adding filters to a filter set
There are two kinds of filters you can add to a filter set: input and output. Input filters check packets received
from the Internet, destined for your network. Output filters check packets transmitted from your network to the
Internet.
Packets in the Netopia Firmware Version 5.4 pass through an input filter if they originate in the WAN and through an output filter
if they’re being sent out to the WAN.
The process for adding input and output filters is exactly the same. The main difference between the two
involves their reference to source and destination. From the perspective of an input filter, your local network is
the destination of the packets it checks, and the remote network is their source. From the perspective of an
output filter, your local network is the source of the packets, and the remote network is their destination.
To add a filter, select Display/Change Filter Set in the Filter Set screen. From the pop-up menu, select the filter
set to which you will add a filter. The Display/Change Filter Set screen appears.
Type of filter Source means Destination means
Input filter The remote network The local network
Output filter The local network The remote network
The Netopia Router
input filter
output filter
LAN WAN
packet
packet