Netopia R5000 User Reference Manual page 192

13-14 User's Reference Guide
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 R5000 Series Router 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.
Type of filter
Input filter
Output filter
In this section you'll learn how to add an input filter to a filter set. Adding an output filter works exactly the same
way, providing you keep the different source and destination perspectives in mind.
To add an input filter, navigate to the Display/Change Filter Set screen and select Display/Change Filter Set.
Main
Menu
A popup menu displays a list of the filter sets you have created.
WAN
output filter
System
Configuration
packet
input filter
packet
The Netopia Router
Source means
The remote network
The local network
Filter
Sets
LAN
"Destination" means
The local network
The remote network
Display/Change
Filter Set