A Sample Ip Filter Set - Netopia Router PN Series Reference Manual

Security 7-25
A sample IP filter set
This section contains the settings for a filter set, called Basic Firewall,
which is part of the Netopia Router's factory configuration. You can
add Basic Firewall to your connection profiles or the answer profile
(see "Connection profiles for ISDN and Leased lines" on page 2-13
and "Default profile" on page 2-39).
Basic Firewall blocks undesirable traffic originating from the WAN (in
most cases, the Internet), but passes all traffic originating from the
LAN. It follows the conservative "that which is not expressly permitted
is prohibited" approach: unless an incoming packet expressly
matches one of the constituent input filters, it will not be forwarded to
the LAN.
The five input filters and one output filter that make up Basic Firewall
are shown in the table below.