Firewalls For Dummies
Introduction
Welcome to Firewalls For Dummies, a book written to help the average
Joe understand how firewalls work and how to configure a firewall.
This book meets the needs of the person just finding out about computers,
as well as the network administrator who needs to implement his or her first
firewall.
But what is a firewall, you may ask? The quick-and-dirty definition is that a
firewall is a boundary network device that resides between a private network
and the Internet. The firewall is configured to inspect the network traffic that
passes between the Internet and your network and only allows the network
protocols that you desire to pass through the firewall. If a protocol isn’t
included in the approved list, the firewall discards the packets of data and
prevents them from entering the network.
Firewalls bring to mind visions of the computer geek at the office, sitting in
a darkened closet with his router and handy toolkit, warding off hackers as
they attack from the Internet. This book attempts to shed some light on the
subject by breaking down the myths around the firewall so that you can
understand what a firewall does and how it’s configured.
This book explains firewalls in normal, everyday language so that you can
learn about them. In addition, you can laugh along with us as we relate stories
from the trenches where we have configured firewalls. After you read
the book, you’ll have the confidence to configure your firewall to allow applications
such as e-mail or Web servers to securely interact with the Internet.
In addition to firewalls, we also look at intrusion detection software meant
for the at-home user, such as ZoneAlarm and Norton Personal Firewall, which
help detect network attacks as they happen. The sooner you know an attack
is taking place, the sooner you can react to the attack and minimize the
damage that an attacker inflicts.
We want you to feel that installing a firewall is no big deal when you understand
the purpose that a firewall serves and the basics of configuring a firewall
