Front cover - IBM Redbooks

equests from numerous users, and maintains rigorous control over the
resources to ensure that one user doesn't affect any other user.
Operating system tasks
The operating system is responsible for various tasks within the computing
environment. These tasks are often what makes one operating system more
reliable or easier to use than another. How the OS handles these tasks
determines the real power of the operating system:
► Processor management: The operating system needs to ensure that each
application gets a share of the processor's time, and that the processor is
used efficiently to accomplish real work.
► Memory management: This defines the methods by which the operating
system allocates memory to applications and operating system functions.
► Device management: Because a computer system is composed of various
hardware components (hard drive, monitor, mouse, keyboard, and so on), the
operating system must be able to manage how these components interact
with each other.
► Storage management: The operating system not only controls active
resources, but defines how files and data are stored in a reliable fashion.
► Application interface: An operating system is really a bridge between
applications and the computer's resources, which means that it must provide
application programming interfaces (APIs) for applications to connect.
► User interface: Whether this is via a command line or a graphical user
interface (GUI), the operating system is responsible for interacting with the
end user.
This is a very brief summary of the major tasks that an operating system should
handle.
The following sections describe security-related issues that the operating system
must deal with to maintain confidentiality, integrity, and availability of system
resources. We provide an overview of the two most common operating system
families and the security features they include. We also describe the most
common methods by which these security features can be attacked or bypassed,
and how to protect against these types of attacks.
From here on, we use as reference two key security books that every
administrator of Windows or UNIX systems should have in their library, namely:
► Maximum Windows 2000 Security (Sams, 2001, ISBN 0672319659)
► Maximum Linux Security (Sams, 1999, ISBN 0672316706)
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