The most well-known security device is the firewall. By conventional
definition, a firewall is a partition made of fireproof material designed to
prevent the spread of fire from one part of a building to another. A firewall
can also be used to isolate one compartment from another. When applying the
term firewall to a computer network, a firewall is a system or group of systems
that enforces an access control policy between two or more networks
.
All
firewalls fall within three classes:
-
Appliance-based firewalls – Appliance-based firewalls are hardware
platforms that are designed specifically as dedicated firewalls. The appliance
may serve other functions, but they are secondary to the firewall feature
set.
-
Server-based firewalls – A server-based firewall consists of a
firewall application that runs on a network operating system (NOS) such as
UNIX, NT or Win2K, or Novell. The underlying operating system is still present,
so vulnerabilities and resource use of the operating system must be taken into
consideration when implementing a this type of firewall.
-
Integrated firewalls – An integrated firewall is implemented by
adding firewall functionality to an existing device.
Cisco provides a full lineup of firewall solutions. This course will
help students design, install, and configure firewalls using IOS Firewall
routers and PIX Security Appliances.
While the PIX Security Appliance
and Cisco IOS Firewall will be the focus of this course, students should
understand that other Cisco firewall options and other vendor firewalls are
available. A basic understanding of the PIX Security Appliance and Cisco IOS
Firewall should allow students to easily transition to other manufacturer
firewalls if needed. While it is beyond the scope of this class to go into
detail on these products, it is recommended that students familiarize
themselves with each of them.