Introduction To Broadband Router Technology; Introduction To Firewalls - D-Link DI-804 User Manual

Introduction to Broadband Router Technology

A router is a device that forwards data packets from a source to a
destination. Routers work on the OSI layer 3, which forwards data packets
using IP addresses and not a MAC address. A router will forward data
from the Internet to a particular computer on your LAN.
The information that makes up the Internet gets moved around using
routers. When you click on a link on a web page, you send a request to a
server to show you the next page. The information that is sent and received
from your computer is moved from your computer to the server using
routers. A router also determines the best route that your information
should follow to ensure that the information is delivered properly.
A router controls the amount of data that is sent through your network
by eliminating information that should not be there. This provides security
for the computers behind your router because computers from the outside
cannot access or send information directly to any computer on your
network. The router determines which computer the information should be
forwarded to and sends it. If the information is not intended for any
computer on your network, the data is discarded. This keeps any unwanted
or harmful information from accessing or damaging your network.

Introduction to Firewalls

A firewall is a device that sits between your computer and the Internet
that prevents unauthorized access to or from your network. A firewall can
be a computer using firewall software or a special piece of hardware built
specifically to act as a firewall. In most circumstances, a firewall is used to
prevent unauthorized Internet users from accessing private networks such
as corporate LAN's and Intranets.
A firewall watches all of the information moving to and from your
network and analyzes each piece of data. Each piece of data is checked
against a set of criteria that the administrator configures. If any data does
not meet the criteria, that data is blocked and discarded. If the data meets
the criteria, the data is passed through. This method is called packet
filtering.
A firewall can also run specific security functions based on the type of
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