The most important first step in developing
a secure
environment is to avoid, wherever possible, having your Linux system
being the
first line of defense from outside attack. The best way to do this is
to ensure
that you have a firewall installed between your Linux system (or the
network on
which it is installed) and the connection to the internet. If, for
example,
your Linux system is currently connected directly to a cable or DSL
modem box
then you will need to think seriously about installing a router or
wireless base
station that includes a firewall feature between the modem and your
Linux
system. Linux does come with a firewall that can be configured to
protect you and we cover this later in the book. It is better,
however, not to rely solely on this.
A firewall essentially stands between your
computer or
network on which your computer resides and shields it from the dangers
lurking
on the internet. It can either be a software program that runs on a
computer
system or it can be built into a hardware device such as a wireless
base
station or router hub. In this chapter we are going to look at
firewalls as a
part of a wired or wireless hub. In later chapters we will look at
configuring
the firewall software on a Linux system to provide a second layer of
defense against
attack.
