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Chapter 5 Configuring the Router's Security
General
The "General" screen is used to configure the Router's basic security settings.
The firewall regulates the flow of data between the local network and the Internet.
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 local network users
access to required Internet services.
The firewall rules specify what types of services available on the Internet can be
accessed from the local network and what types of services available in the local
network can be accessed from the Internet. Each request for a service the firewall
receives, whether originating in the Internet or from a computer in the local net-
work, is checked against the firewall rules to determine whether the request should
be allowed to pass through the firewall. If the request is permitted to pass, all sub-
sequent data associated with this request (a "session") will also be allowed to pass,
regardless of its direction.
For example, when accessing a website on the Internet, a request is sent out to the
Internet for this site. When the request reaches the Router, the firewall identifies
the request type and origin (
and a specific computer in the local network, in
HTTP
this case). Unless the Router is configured to block requests of this type from this
computer, the firewall allows this request to pass out onto the Internet. When the
website is returned from the web server, the firewall will associate it with this ses-
sion and allow it to pass, regardless of whether
access from the Internet to
HTTP
the local network is blocked or permitted.
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