Access controls are common form of controls encountered in the boundary subsystem by restricting the use of system resources to authorize users, limiting the actions authorized users can take with these resources and ensuring that the users obtain only authentic system resources.
Current systems are designed to allow users to share their resources. This is done by having a single system simulate the operations of several systems, where each of the simulated system works as virtual machine allowing more efficient use of resources by lowering the idle capacity of the real system. Here, a major design problem is to ensure that each virtual system operates as if it were totally unaware of the operations of the other virtual systems. Besides increased scope exists for unintentional or deliberate damage to system resources / user’s actions.