Netopia Router PN Series - Manual (Page 148)

7-6 Reference Guide
About filters and filter sets
Security should be a high priority for anyone administering a network
connected to the Internet. Using packet filters to control network
communications can greatly improve your network’s security.
The Netopia Router’s packet filters are designed to provide security
for the Internet connections made to and from your network. You
can customize the router’s filter sets for a variety of packet filtering
applications. Typically, you use filters to selectively admit or refuse
TCP/IP connections from certain remote networks and specific
hosts. You will also use filters to screen particular types of
connections. This is commonly called firewalling your network.
Before creating filter sets, you should read the next few sections to
learn more about how these power ful security tools work.
What’s a filter and what’s a filter set?
A filter is a rule that lets you specify what sort of data can flow in
and out of your network. A particular filter can either be an input
filter—one that is used on data (packets) coming in to your network
from the Internet—or an output filter—one that is used on data
(packets) going out from your network to the Internet.
A filter set is a group of filters that work together to check incoming
or outgoing data. A filter set can consist of a combination of input
and output filters.
How filter sets work
A filter set acts like a team of customs inspectors. Each filter is an
inspector through which incoming and outgoing packages must
pass. The inspectors work as a team, but each inspects every
package individually.