How The Firewall Works - Toshiba Magnia SG20 User Manual

Establishing an Internet Connection

How the firewall works

The primary purpose of a firewall is to provide a single point of entry where a defense
can be implemented, allowing access to the Internet from within the organization while
controlling access from the Internet to the Magnia SG20.
The firewall works by refusing nearly all direct access to your Magnia SG20 from the
Internet. No one may access any application, file, or resource within your firewall from
the Internet, but any application (from the local network) may access the Internet and
conduct bidirectional access transparently.
All access to the Internet is channeled through a single access point on the server, called
the gateway. The firewall incorporated into this gateway is a set of programs designed to
deny access to your network from the outside unless access has been granted. By
refusing access to your local network resources, the firewall prevents potentially
damaging use of your local network computers by outside sources.
The server's firewall is active for all connections made on the public Ethernet port (used
for broadband connections to the Internet) as well as all communications on the modem
port (used for dial-up Internet connections). This logically separates the server from
"remote" access equipment, but does not restrict access by local network clients.
Local computers
Firewall diagram
The firewall feature is set up to provide maximum protection for your network, and should
meet most network needs without change. However, you may occasionally need to
enable special access to your local network by allowing additional outside network traffic
to pass through the firewall. For this reason, a variety of special-case firewall
configuration options are available.
Firewall
Broadband connection
Modem connection
Magnia SG20
Internet security and the firewall
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