Skip to main content

Protection and security

 Protection and security

Protection in computer system

 

·         In the system with contiguous memory allocation,  protection is usually accomplished by the use of limit registers. Each program  is assigned a specific limit in term of address space . whenever any reference is made to an instruction of the limit register is checked to ensure that reference is within the bound of program otherwise the access to memory is denied.

·         In paging system, protection is achieved by the use of a page table. This page table list all the pages that a program can access.

·         In addition the table store access rights such as read, write or execute for each individual page.

·         In a system that uses segmentation, protection is accomplished by the use of segment table . each process has its segment table

 



·         In case of files stored on secondary storage devices suchj as disks, access rights are associated with each file system. Any user who tries to access a file may be denied the access depending upon the type of priviledge given to each other

·          Security refers to method of protecting information stored in the system, as well as the physical resource of the computer system from unauthorized access , malicious destruction or alteration and accidental introduction of inconsistency

·         Authorized users are those, whose identity are known and are allowed to use system resources whereas unauthorized users are those who are not allowed to use system resources.

 

Comments

Popular posts from this blog

Monolithic Architecture

  Monolithic Architecture Monolith means composed all in one piece. The  Monolithic  application describes a single-tiered  software  application in which different components combined into a single program from a single platform. Components can be: Authorization — responsible for authorizing a user Presentation — responsible for handling HTTP requests and responding with either HTML or JSON/XML (for web services APIs). Business logic — the application’s business logic. Database layer — data access objects responsible for accessing the database. Application integration — integration with other services (e.g. via messaging or REST API). Or integration with any other Data sources. Notification module — responsible for sending email notifications whenever needed. Example for Monolithic Approach Consider an example of Ecommerce application, that authorizes customer, takes an order, check products inventory, authorize payment and ships ordered products. This applicat...

Service provided By An Operating System.

  List of five service provided by an operating system. Explain how  each provides convenience to users?     The main purpose of operating system is to provide environment for the execution of programs. Thus an operating system provides certain services to program and the users of those programs. However , different operating system can provide different set of service. Some of the basis services provided by operating system are: 1.         Program execution ·          Operating system provides a convenient environment where users can run their programs ·          The operating system performs memory allocation to programs, load them into appropriate location so that they can execute. The users need not to worry about all these tasks.   2.         I/O Operation ·        ...

Message Delivery Protocol

  Message Delivery Protocol ·          A protocol is a set of rules and conventions shared by communicating entities . ·          Message passing can be blocking or non blocking . ·          In blocking protocol , a sender process is blocked till the message selivered to the . in this case , sender process has guarantee that the message sent by it ie delivered before it continues its execution . A blocking protocol normally includes: 1.        Blocking send : the sender process is blocked until the message is received by the receiving process or by the mailbox. 2.        Blocking receive : the receiver nlocks until a message is available thus when both sender as well as receiver is blocked ,it is known as rebdevezevous . this combination allows for tight sysnchronization between process. ·...

Thread

Thread What is Thread? A thread is a flow of execution through the process code, with its own program counter that keeps track of which instruction to execute next, system registers which hold its current working variables, and a stack which contains the execution history. A thread shares with its peer threads few information like code segment, data segment and open files. When one thread alters a code segment memory item, all other threads see that. A thread is also called a  lightweight process . Threads provide a way to improve application performance through parallelism. Threads represent a software approach to improving performance of operating system by reducing the overhead thread is equivalent to a classical process. Each thread belongs to exactly one process and no thread can exist outside a process. Each thread represents a separate flow of control. Threads have been successfully used in implementing network servers and web server. They also provide a suitable foundation ...

Easytolearn E-book 2

                                                                                                                                                                          Description:here we give you pdf. about classification of operating system in which  we provide all information of classification in detail.