Security Protocols and System Architecture

Definition: Methods and standards designed to secure data transmission and communication systems.
Types:
- Transport Layer Security (TLS): Encrypts data in transit; successor of SSL.
- Secure Socket Layer (SSL): Provides encryption for web browsers; now considered obsolete.
- Internet Protocol Security (IPsec): Protects IP communications by authenticating and encrypting each IP packet.
- Secure Hypertext Transfer Protocol (HTTPS): Secure version of HTTP; uses TLS/SSL for secure communications.
Authentication protocols:
- Kerberos: Network authentication protocol using tickets to allow nodes to prove their identity.
- OAuth: Open standard for access delegation; widely used for token-based authentication.

Definition: The conceptual model defining the structure, behavior, and more of a system.
Components:
- Hardware: Physical devices and infrastructure.
- Software: Operating systems, applications, and services.
- Data: Stored information and its management.
Types:
- Monolithic Architecture: Single unit where all components operate together.
- Microservices Architecture: Breaks applications into smaller, independently deployable services.
- Client-Server Architecture: Divides tasks between service providers (servers) and service requesters (clients).
Layers:
- Presentation Layer: User interface and interaction.
- Application Layer: Business logic and data processing.
- Data Layer: Data storage and management.

Definition: The act of managing the execution of processes in an operating system.
Key Concepts:
- Process: An instance of a running program, containing executable code and current activity.
- Threads: Lightweight processes that share resources but can run independently.
Activities:
- Creation: Initiating a process via system calls (fork, exec).
- Scheduling: Determining the order of process execution using algorithms (Round Robin, First-Come-First-Served).
- Synchronization: Mechanisms to control access to shared resources (semaphores, mutexes).
- Terminating: Ending a process when complete or when terminating due to errors.

Definition: Fundamental concepts related to computer networks and communication.
Components:
- Nodes: Devices like computers and servers connected to a network.
- Links: Physical connections (cables, wireless) enabling communication.
Types of Networks:
- Local Area Network (LAN): Covers small geographic areas, like a home or office.
- Wide Area Network (WAN): Covers larger areas, connecting multiple LANs (e.g., the Internet).
Protocols:
- Transmission Control Protocol (TCP): Ensures reliable transmission of data by establishing a connection before sending data.
- User Datagram Protocol (UDP): Provides a connectionless protocol for faster transmission but without guaranteed delivery.
- Internet Protocol (IP): Responsible for addressing and routing packets across networks.
Topologies:
- Star: Central node connected to all devices.
- Bus: Single central cable, with devices connected along its length.
- Ring: Each device connected to two others, forming a circular pathway.

Goal: Protect data transmission and communication systems
Examples:
- TLS (Transport Layer Security): Encrypts data during transmission, replacing SSL
- SSL (Secure Socket Layer): Provides encryption for web browsers, now considered outdated
- IPsec (Internet Protocol Security): Protects IP communications by verifying identities and encrypting data
- HTTPS (Secure Hypertext Transfer Protocol): Secure version of HTTP using TLS/SSL for safe communication
Authentication protocols:
- Kerberos: Uses tickets to verify identities of connected devices
- OAuth: Open standard for access delegation, especially used for token-based authentication

Definition: Blueprint for a system's structure, behavior, and other aspects
Components:
- Hardware: Physical devices and infrastructure
- Software: Operating systems, applications, and services
- Data: Stored information and its management
Types of System Architecture:
- Monolithic: All components work together within a single unit
- Microservices: Divides applications into independent services that can be deployed separately
- Client-Server: Separates tasks between service providers (servers) and requestors (clients)
Layers:
- Presentation: User interface and interaction
- Application: Business logic and data processing
- Data: Data storage and management

Goal: Manage the execution of processes in an operating system
Key Concepts:
- Process: Instance of a running program, including code and current activity
- Threads: Lightweight processes sharing resources but running independently
Process Activities:
- Creation: Initiating a process using system calls
- Scheduling: Determining execution order using algorithms like Round Robin or First-Come-First-Served
- Synchronization: Controlling access to shared resources using techniques like semaphores or mutexes
- Terminating: Ending a process when complete or due to errors

Definition: Fundamental concepts related to computer networks and communication
Components:
- Nodes: Devices connected to a network (e.g., computers, servers)
- Links: Physical connections (cables, wireless) enabling communication
Types of Networks:
- LAN (Local Area Network): Covers small areas like homes or offices
- WAN (Wide Area Network): Connects multiple LANs over larger areas (e.g., the internet)
Protocols:
- TCP (Transmission Control Protocol): Ensures reliable data transmission by establishing a connection before sending data
- UDP (User Datagram Protocol): Connectionless protocol for faster transmission but without guaranteed delivery
- IP (Internet Protocol): Responsible for addressing and routing data packets between networks
Topologies:
- Star: Central node connected to all devices
- Bus: Single central cable with devices connected along its length
- Ring: Each device connected to two others in a circular pathway