ABSTRACT
In an age of increasingly sophisticated security tools
(e.g., firewalls, virtual private networks, intrusion detection
systems, etc.), Many people do not consider operating
system security a very sexy topic. Indeed, given that the
UNIX operating system was originally developed in 1969
and that multiple full-length books have been written on
protectingUNIXmachines, onemight be tempted to dismiss
the entire topic as “old hat.” Nevertheless, operating system
security is a crucial component of an overall security pro-
gram. In the words of Anup Ghosh,[1] the operating system
is “the foundation for any software that runs on a machine,”
and this is just as true in the era of E-commerce as it was in
the past. Thus, security practitioners who are even indirectly
responsible for the protection of UNIX machines need to
have at least a basic understanding of UNIX security. This
entry attempts to address that need by providing an overview
of security services common to all flavors of UNIX; security
mechanisms available in trusted UNIX are beyond the scope
of this entry (but see Table 1).
