Silberschatz et al. mention that “we can view an operating system from several vantage points. One view focuses on the services that the system provides; another, on the interface that it makes available to users and programmers; a third, on its components and their interconnections.” Throughout history, there have been multiple different iterations of Operating Systems design and many of them were either directly or indirectly influenced by the MULTICS system of the 1970s. Two of the most popular Operating Systems currently in use today is Windows and the various flavors of Linux where one of the most noticeable differences is that one is open-source and the other is considered closed-source. “Open-source operating systems are those available …show more content…
Security and usability are two things that must be balanced in order to provide a product or design that is accepted by the users and this is a significant consideration for any OS developer. According to Microsoft, their Windows Security Model revolves around two elements which are “User authentication” and “File System Security” and it is easily noticeable how these elements correlate with the two goals of an OS (https://msdn.microsoft.com/en-us/library/cc767976.aspx). Microsoft Windows OS is considered a monolithic design where many of the critical system functions reside in the kernel address space to benefit performance reasons. While the OS is in kernel mode the user has unrestricted access to the system memory and external devices. A key difference between the Windows and Linux kernels is that “the Linux Kernel has all the access to the memory and can do whatever it wants with it. In order to keep himself alive it will start to kill other processes to acquire memory for him, if that will not happen, the system will crash.” (Windows Kernel vs Linux Kernel, 2016) The Windows kernel will just swap out memory when it’s required. At the same time, Windows is one of the most commonly used Operating Systems in an “Enterprise” …show more content…
Additionally, the Linux kernel is described as modular, providing for extensibility by adding functionality through the use of Linux modules. This allows for the core kernel to be small and efficient with a small attack surface than a pure monolithic design such as Windows. Originally, Linux implemented Discretionary Access Control (DAC) as it was based on the Unix design where the owner of the object has the ability to give permissions to access an object to a specific user. The National Security Agency (NSA) developed the Security-Enhanced Linux version of the OS, which provided support for a Mandatory Access Control (MAC) architecture often utilized by government agencies. “SELinux access controls are determined by a policy loaded on the system which may not be changed by careless users or misbehaving applications. SELinux also adds finer granularity to access controls.” (Pomeroy and Weifeng, 2015) Linux utilizes file system namespaces which provide isolation between running processes and virtualizes system resources. In terms of memory management, the Linux kernel supports memory mapping, dynamic memory allocation, as well as over commitment. Linux distributions typically enforce the “Least Privilege” design principle by default where a user must be authenticated in order to have elevated permissions execute