Information Security 3: Basics of Unix and Network Administration

Introduction to the Course

• Course Sequence:

  • Information Security 1: Introduction to info security from a systems perspective.
  • Information Security 2: Focus on using hardware features to build secure systems (architectural aid).
  • Information Security 3: Basics of UNIX and network administration with emphasis on security.
  • Future Courses: Will cover security at higher layers above OS and applications.

• Course Structure:

  • 60 modules, 20 minutes each totaling 20 hours.
  • 8 programming assignments (MCQ and programming).
  • Requires basic programming knowledge.
  • Includes an in-course exam for certification.

Module 1: Fundamentals of Operating Systems

Different User Perspectives

• End User:

  • Uses application software (e.g., word processor, browser).
  • Does not need to know how the software works.

• Application Programmer:

  • Develops software using system software features.
  • Uses features like memory allocation (e.g., malloc in C).

• System Programmer/OS Programmer:

  • Develops system software, dealing closely with hardware.
  • Needs to know about hardware use (disk reading, printer use, etc.).

System Software and Application Programmer Interface (API)

• System Software Examples:

  • C library functions, desktop environments, databases (e.g., MySQL), device drivers.
  • Provides APIs for application development.

• Operating System (OS):

  • Acts as a manager for software and hardware interaction.
  • Provides system software for application programmers.

Layers of Computer Systems

• Four Layers:
  • Hardware: Base layer.
  • Operating System (OS): Manages hardware resources.
  • System/Application Programs: Compilers, databases, etc.
  • Users: End users interact with applications.

Interaction and Importance of OS

• Service Request Cycle:

  • User input -> application -> OS -> hardware -> operation -> result to application -> user.

• Why OS is crucial:

  • Abstraction of hardware from users.
  • Ensures efficient hardware use and correct operations.

Types of Operating Systems

• Batch Processing OS: Handles tasks in batches.
• Time-Sharing OS: Multiple users share system time.
• Real-Time OS: Ensures tasks are done within strict time limits.
• Network OS: For managing networked devices.
• Distributed OS: Manages multiple computers as a single system.
• Embedded OS: Lightweight for small devices (e.g., IoT).

Additional Classifications

• Single vs Multi-user OS: E.g., personal desktops vs mail servers.
• Single task vs Multitasking OS: Focus on task execution.

Evolution of Operating Systems

• Transition from batch processing in mainframes to interactive, networked, handheld systems.
• Modern OS needs to address interactive, real-time, and networked environments.

Role and Definition of Operating Systems

• Resource Allocation: Manages and allocates resources.

• Conflict Resolution: Serializes tasks to avoid conflicts (e.g., managing print jobs).

• Error Management: Stops incorrect operations, reports errors.

• No Universally Accepted Definition:

  • OS interacts with multiple hardware and software types.
  • Kernel: Core part running constantly.

Starting and Running an OS

• Boot Process:

  • Starts from ROM -> loads bootable device -> loads OS kernel.
  • Ensures constant operation from startup to shutdown.

• Understanding OS Functioning:

  • Requires knowledge of computer organization and operation.

This course will focus on understanding these fundamentals and preparing for advanced topics in the following courses.