A Comparative Study of Access Control Models in Multi-User Operating Systems

Access control is an important part of operating system security because it makes sure that only approved users and processes can get to system resources. This research looks at the differences and similarities between the three most common access control methods in multi-user operating systems. These are Discretionary Access Control (DAC), Mandatory Access Control (MAC), and Role-Based Access Control (RBAC). their architecture, how they work, pros and cons when it comes to privacy, integrity, and usefulness, as well as how they are implemented. Through a review of the literature and experiments done on Linux, Windows, and UNIX systems, the study checks how well each model works in various security and task situations. The results show that DAC is more flexible and easy to handle, but it is also more likely to be abused. MAC protects sensitive systems better, but it is less flexible, and RBAC strikes a balance between security and administrative efficiency. Modern operating systems with multiple users could be safer and more flexible if they used a hybrid method that combined RBAC and MAC elements.