MCSA/MCSE Self-Paced Training Kit (Exam 70-270): Installing ...

15-46 Chapter 15 Configuring Network and Internet Connections
Lesson 5: Configuring Windows Firewall
A firewall protects a computer from the outside world (specifically, the Internet) by
blocking all network traffic except that which you specifically configure the firewall to
allow through. This section introduces firewalls and looks at the software-based firewall
that is included with Windows XP Professional: Windows Firewall.
After this lesson, you will be able to
■ Explain how firewalls protect computers.
■ Enable or disable Windows Firewall for all network connections.
■ Enable or disable Windows Firewall for a specific network connection.
■ Configure advanced options for Windows Firewall.
■ Troubleshoot connectivity problems that are associated with Windows Firewall.
Estimated lesson time: 40 minutes
Introducing Windows Firewall
A firewall acts as a security system that creates a border between the computer or network
and the Internet. This border determines what traffic is allowed in the local network
or computer. Firewalls help keep hackers, viruses, and other malicious activity
from infiltrating the computer and network. A network-based firewall is a device
that protects an entire network. A host-based firewall is a program that protects a
single computer. Windows XP Professional includes a software firewall named Windows
Firewall.
Windows Firewall is installed when you install Windows XP Service Pack 2, and is an
updated version of the Internet Connection Firewall found on versions of Windows XP
with Service Pack 1 and previous. Windows Firewall is a stateful, host-based firewall
that drops all incoming traffic that does not meet one of the following conditions:
■ Solicited traffic (valid traffic that is sent in response to a request by the computer)
is allowed through the firewall.
■ Expected traffic (valid traffic that you have specifically configured the firewall to
accept) is allowed through the firewall.
Windows Firewall has the following characteristics:
■ Is enabled by default for all network connections. This differs from Internet Connection
Firewall, which was not enabled by default.