To a large extent, this book is platform-independent. Because most of
the information provided here consists of general principles, most of
it should be applicable to you, regardless of what equipment,
software, and networking you are using. The most platform-specific
issue is what type of system to use as a bastion host. People have
successfully built bastion hosts (which we describe in Chapter 5 of this book) using all kinds of computers,
including UNIX systems, Windows
NT machines, Macintoshes, VMS VAXes, and others.
Having said this, we must acknowledge that there is a strong
UNIX orientation to the specific examples in this
book. There are several reasons for this. This is a book about
building firewalls, and at the present time, the richest source of
freely available tools for accomplishing this task is in the
UNIX world. As a result, the vast majority of the
firewalls being built today use UNIX systems as
their bastion hosts (although, of course, many other types of machines
may be included in the overall configurations). We expect that this
situation may change in the next few years, as more commercial systems
become available for many types of systems. Another reason is, of
course, that our own experience is primarily in the
UNIX world.
