Access control/protection Types of OS

3.1 Explain the purpose of operating systems.

📘CompTIA ITF+ (FC0-U61)

1. Access Control / Protection

Access control is how an operating system (OS) manages who can access what resources on a computer or network. The goal is to protect data and system resources from unauthorized use.

Key Concepts:

User Accounts
- Every person who uses a computer gets a user account with a username and password.
- The OS uses this account to identify the user and determine what they can access.
Permissions / Rights
- Permissions define what a user can do:
  - Read – view a file
  - Write – edit or create a file
  - Execute – run a program
- Example: On a Windows workstation, a standard user might be able to open files but cannot install software without admin rights.
Authentication
- The OS verifies a user’s identity before granting access.
- This could be via:
  - Password
  - Biometric login (fingerprint, face ID)
  - Security token or smart card
Authorization
- Once a user is verified, the OS decides what they are allowed to do.
- Example: On a server, some users may have access to a database, while others cannot.
Security Models
- OSs may implement security models like Discretionary Access Control (DAC) or Mandatory Access Control (MAC).
- DAC: Users control access to their own files.
- MAC: The system enforces strict rules (often used on servers or secure networks).
Protection Mechanisms
- File Permissions: Control access to files/folders.
- User Groups: Group users with similar access rights together.
- Auditing & Logging: Track who accesses what for security monitoring.

2. Types of Operating Systems

Operating systems come in different types, each optimized for specific environments.

a) Mobile Device OS

Found in smartphones and tablets.
Examples: Android, iOS
Key Features:
- Touchscreen support
- Mobile app management
- Power efficiency
- Security features like app sandboxing (apps cannot interfere with each other)
Use in IT: Mobile device management (MDM) software can control access to corporate email or documents.

b) Workstation OS

Found on personal computers used for office or individual tasks.
Examples: Windows 11, macOS, Linux Desktop distributions
Key Features:
- GUI (Graphical User Interface) for user interaction
- Multi-user support (different accounts on one PC)
- File management, networking, and device support
Use in IT: Workstations are used for office productivity, coding, graphic design, or client-side computing.

c) Server OS

Runs on servers that provide services to other computers.
Examples: Windows Server, Linux Server distributions
Key Features:
- Handles multiple users at once
- Provides network services: email, web hosting, file sharing
- Security-focused: user authentication, permission management
Use in IT: Hosts databases, web applications, or cloud services used by many clients simultaneously.

d) Embedded OS

Found in special-purpose devices where computing is part of the device.
Examples: Smart TVs, printers, medical devices, IoT devices
Firmware is often part of embedded systems:
- Firmware: Software programmed into the hardware to control the device.
- Usually stored in ROM or flash memory and not meant to be modified often.
Use in IT: Embedded OS ensures the device works reliably and securely, like a printer in a networked office.

e) Hypervisor (Type 1)

A hypervisor allows you to run multiple virtual machines (VMs) on the same physical hardware.
Type 1 Hypervisor runs directly on the physical server (bare-metal), not on top of another OS.
Examples: VMware ESXi, Microsoft Hyper-V, Xen
Key Features:
- High performance because it communicates directly with hardware
- Isolates VMs for security
- Centralized management of resources like CPU, memory, and storage
Use in IT: Data centers and cloud environments run multiple VMs on one server to save hardware costs and improve flexibility.

Summary Table for Quick Review

Type of OS	Example	Key Use / Feature	IT Context Example
Mobile Device OS	Android, iOS	Touchscreen, app sandboxing	Corporate email on mobile phones
Workstation OS	Windows, macOS, Linux	GUI, file & device management	Office PCs, development machines
Server OS	Windows Server, Linux Server	Multi-user, network services, security	Web servers, file servers
Embedded OS	Printer OS, IoT OS	Specialized device control, firmware	Networked printers, IoT sensors
Hypervisor Type 1	VMware ESXi, Hyper-V	Run multiple VMs on hardware efficiently	Virtualized servers in a data center

Exam Tip

Remember that access control and protection are about securing who can do what.
Mobile, workstation, server, embedded OS, and hypervisors differ in purpose, user interface, and IT usage.
Focus on where they are used in IT environments and how they protect or manage resources.