PRG AV4202N
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OGU 930500275-A1
Security Section
put rules, control the order of logically similar sets of rules and make a distinc-
tion between rules that apply to WAN and LAN network devices.
GENERAL
Use the 'General' screen to configure the gateway's basic security settings.
The firewall regulates the flow of data between the home network and the Inter-
net. Both incoming and outgoing data are inspected and then either accepted
(allowed to pass through the Router) or rejected (barred from passing through
the Router) according to a flexible and configurable set of rules. These rules are
designed to prevent unwanted intrusions from the outside, while allowing home
users access to the Internet services that they require.
The firewall rules specify what types of services available on the Internet may
be accessed from the home network and what types of services available in the
home network may be accessed from the Internet. Each request for a service
that the firewall receives, whether originating in the Internet or from a computer
in the home network, is checked against the set of firewall rules to determine
whether the request should be allowed to pass through the firewall. If the re-
quest is permitted to pass, then all subsequent data associated with this request
(a “session”) will also be allowed to pass, regardless of its direction.
For example, when you point your Web browser to a Web page on the Internet,
a request is sent out to the Internet for this page. When the request reaches the
Router the firewall will identify the request type and origin - HTTP and a specific
PC in your home network, in this case. Unless you have configured access con-
trol to block requests of this type from this computer, the firewall will allow this
request to pass out onto the Internet. When the Web page is returned from the
Web server the firewall will associate it with this session and allow it to pass,
regardless of whether HTTP access from the Internet to the home network is
blocked or permitted.
The important thing to note here is that it is the origin of the request, not subse-
quent responses to this request, that determines whether a session can be es-
tablished or not. You may choose from among three pre-defined security levels
for the Router: Minimum, Typical, and Maximum (the default setting). The table
below summarizes the behavior of the Router for each of the three security lev-
els.
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