39 CONFIGURING FIREWALL
This chapter covers the following topics:
■Firewall Overview
■Configure Firewall
■Displaying and Debugging Firewall
■Firewall Configuration Example
Firewall Overview A firewall is used to control the network equipment, which accesses the internal
network resources. Setting a firewall at the access entry point of the intranet can
control access to the internal network resources by the external network devices.
In case of multiple entry points, every access entry point should be configured with
a firewall to effectively control the external access. To ensure that all data entering
the intranet is detected by the firewall, the firewall should be set at the intranet
entry point.
A firewall is used not only to connect the Internet, but also to control the access to
some special part of the internal network, such as to protect mainframes and
important resources, such as data, in the network. Access to the protected data
must be filtered through the firewall even if the access is from inside.
The firewall can screen the information, structure and operation of the intranet
from outside by detecting, restricting and modifying data flow overriding the
firewall. At present many firewalls also have other characteristics, for example, to
identify the user, and conduct security processing (encryption) for information.
Figure 170 A firewall isolates the internal network from the Internet
Ethernet
Internet
PC PC PC PC
Server
Firewall