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Top1. Introduction
The preventive control ACM model provides accountability for individuals who are accessing sensitive information on application, system software, server and network. We have to develop the multi-dimensional un order ACM model for risk mitigation on large scale UNIX real time operating system based on available technology, business and resources. We have to prevent our data and service from public resources and unauthorized user over a complex parallel & distributed operating system (Schneier, 1996; Weber, 2002). Now a day, increasing the complex business, applications, client, users, and resources over a heterogeneous business domain of the multiple location of WAN, LAN, IT Infrastructure, computer & communications system by IT industries has increased the uncertainty, un order, risk of theft to proprietary information. The operating system control & audit is a primary method of protecting system resources (Processor, Memory, Kernel & File system).
1.1. Real Time Operating System
The most fundamental system program is the operating system, whose job is to control all the resources of the computer and provide a base upon which is the application program can be written. The concept of the operating system as primarily providing its users with a convenient interface is a top-down view. The morden computer system consists of professors, memories, times, firmware, disk, network interfaces, printer and associates with a wide verity of other devices. When a computer or a network has multiple users, the need for managing and protecting the memory, I/O devices and other resources is even greater, since the users might otherwise interface with one another. In addition, users often need to share not only hardware, but information (files, databases, etc.) as well. In short, this view of the operating system holds that its primary task is to keep track of who is using which resources, to grant resource requests, to account for usage, and to mediate conflicting requests from different programs and users (Tanenbaum, 2010). The resource management including multiplexing (sharing), time sharing resources in two ways: in time and in space. When resource is time multiplexed, different programs or users take turns using it. First one of them gets to use the resources, then another, and so on. To determining how the resource is time multiplexed – who goes next and for how long- is the task of the RTOS (Tanenbaum. (2010).
2. Attribute-Based Access Control (Rwx)
The rights (RWX) and permissions are implemented differently in systems based on discretionary access control (DAC) and mandatory access control (MAC). In any ACM, the entities that can perform actions on the system are called subjects, and the entities representing resources to which access may need to be controlled are called objects (Access Control Matrix: data collection). The subjects and objects should both be considered as software entities, rather than as human users: any human user can only have an effect on the system via the software entities that they control. The authorization involves the act of defining access-rights for subjects. The authorization policy specifies the operations that subjects are allowed to execute within a system. The most modern operating systems implement authorization policies as formal sets of permissions that are variations or extensions of three basic types of access: (RWX).
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Read (R): The subject can (R), Read file contents, List directory contents
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Write (W): The subject can change (update) the contents of a file or directory with the following tasks: Update (Add Update Delete Rename)
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Execute (X): If the file is a program, the subject can cause the program to be run. (In Unix-style systems, the “execute” permission doubles as a traverse directory permission when granted for a directory.)