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Security Management

Security Management

Many operating systems include some level of security. Security is based on the two ideas that:
• The operating system provides access to a number of resources, directly or indirectly, such as files on a local disk, privileged system calls, personal information about users, and the services offered by the programs running on the system;
• The operating system is capable of distinguishing between some requesters of these resources who are authorized (allowed) to access the resource, and others who are not authorized (forbidden). While some systems may simply distinguish between “privileged” and “non-privileged”, systems commonly have a form of requester identity, such as a user name. Requesters, in turn, divide into two categories:
1. Internal security: an already running program. On some systems, a program, once it is running, has no limitations, but commonly the program has an identity which it keeps and is used to check all of its requests for resources.
2. External security: a new request from outside the computer, such as a login at a connected console or some kind of network connection. To establish identity there may be a process of authentication. Often a username must be quoted, and each username may have a password. Other methods of authentication, such as magnetic cards or biometric data might be used instead. In some cases, especially connections from the network, resources may be accessed with no authentication at all.
In addition, to the allow/disallow model of security, a system with a high level of security will also offer auditing options. These would allow tracking of requests for access to resources (such as, “who has been reading this file?”).
UI [User Interface] management
Today, most modern operating systems contain Graphical User Interfaces. More modern operating systems are modular, separating the graphics subsystem from the kernel (as is now done in Linux, and Mac OS X, and to a limited extent Windows).
GUIs tend to change with time. For example, Windows has modified its GUI every time a new major version of Windows is released and the Mac OS GUI changed dramatically with the introduction of Mac OS X.