Digital societies

Classification of Networks by Geographical Scope

  • Personal Area Network (PAN)

    • This is the smallest type of network classification.
    • It consists of connected devices that are in close proximity to an individual user.
    • Examples include moving data between a smartphone and a smartwatch, using wireless headphones, or a printer connected directly to a computer.

  • Local Area Network (LAN)

    • A group of computers or peripheral devices connected together within a single site or limited geographical area.
    • Common environments for LANs include homes, schools, or offices/corporations.
    • Their primary purpose is often to share resources, such as files or hardware.

  • Metropolitan Area Network (MAN)

    • A network that covers a larger geographical area than a LAN, typically spanning a city.
    • Use cases include connecting multiple different campuses across a metropolitan zone.
    • Range: Anywhere between 5−50 km5-50\,km.
    • Examples: City-wide Wi-Fi connections, such as the free Wi-Fi provided in New York.

  • Wide Area Network (WAN)

    • A national or international network that connects smaller networks over long distances.
    • The internet is the most prominent example of a WAN.
    • It frequently incorporates multiple LANs, such as those belonging to large international corporations.

Connectivity and Transmission Methods

  • Wired Connectivity

    • These connections use physical cables like Ethernet or fibre-optic lines.
    • Performance: Generally faster and more reliable than wireless alternatives.

  • Wireless Connectivity

    • These connections utilize radio signals to transmit data.
    • Examples include Wi-Fi and Bluetooth.
    • Performance: More flexible and convenient for mobile devices, though they are not always considered optimal due to potential signal interference or lower reliability compared to wired connections.
    • Implementation: Often still requires a physical cable connecting to a Wireless Access Point (WAP), but allows devices to connect without wires.

  • Interoperability

    • This term refers to the standard that allows different technologies to travel, connect, and exchange data without restriction across various network types.

Network Models and Architectures

  • Client-Server Network

    • Data and resources are stored centrally on a powerful central server.
    • Access is granted to individual devices, known as clients, on the network.
    • Advantages: Centralized security and backups, making it suitable for large organizations.
    • Disadvantages: Expensive to implement; often requires expert IT staff to maintain and high bandwidth to function.

  • Peer-to-Peer Network (P2P)

    • A decentralized network structure where there is no central server.
    • Every computer (node) is equally responsible for storing and sharing data.
    • Use cases: Sharing large files (e.g., media downloads), cryptocurrency networks, and features like AirDrop.
    • Tradeoffs: It is more difficult to manage security because there is no central control point, but the network does not depend on a single server to function.

  • Cloud Networks

    • These incorporate network capabilities onto public or private cloud platforms.
    • Configurations can be managed by accessing IP addresses that control the wireless network.
    • Management can be handled off-site, which places data and control in the hands of others, presenting both benefits and risks.

Crucial Network Hardware and Components

  • Network Interface Card (NIC)

    • A device responsible for converting data into a signal for communication.
    • It converts information into digital form to be stored on or transmitted to a server.
    • Can be wired or wireless.

  • Node

    • Any device on a network that can send, receive, and forward data.
    • Examples include computers, routers, or printers.

  • Router

    • Technology that transfers data from one network to another.
    • It determines and uses the most efficient route for data traffic.

  • Modem

    • A device that converts digital data into analogue data and vice versa.
    • This allows information to be transmitted over telephone lines.
    • Often used in conjunction with a router.

  • Wireless Access Point (WAP)

    • A device that creates a wireless local area network (WLAN).
    • It is used to improve or extend physical wireless coverage.

  • Hub

    • A basic device that broadcasts data packets to all other devices on the network.
    • Described as the "least intelligent" network device because it wastes bandwidth by sending data to nodes that do not need it.

  • Switch

    • A device that forwards data packets more efficiently than a hub.
    • It is used by most LANs because it is controllable and ensures data only reaches the intended recipient node.

  • Media Access Control (MAC) Address

    • A physical hardware identifier assigned to every NIC by the manufacturer.
    • It is fixed and consists of 48 bits48\,\text{bits} written in hexadecimal format.

  • Firewall

    • Can be hardware or software-based.
    • Functions as a security measure to inspect and block unauthorized access or prohibited content by filtering incoming and outgoing traffic.

  • Proxy Server

    • Acts as an intermediary between a client and the internet.
    • Used for security, filtering connection requests, and limiting user access.

  • Load Balancers

    • Hardware or software used to distribute network or application traffic across multiple servers to ensure efficiency and reliability.

The Four-Layer Protocol Model and Communication Standards

  • Network Protocols

    • A set of agreed-upon rules stating how to format, send, and receive data.
    • Both sides of a transmission must accept the protocol to communicate.

  • The Four Layers:

    1. Application Layer: Protocols like HTTP and HTTPS are used here.
    2. Transport Layer: Manages the breakdown and reconstruction of data.
    3. Internet Layer: Manages addressing and routing.
    4. Physical Network Layer: The hardware level of the transmission.

  • Domain Name Server (DNS)

    • Acts as a translator that converts human-readable domain names into machine-readable IP addresses.

  • Transmission Control Protocol (TCP)

    • Located in the transport layer.
    • It breaks data into smaller sections called packets to be sent and then recreates them at the destination.
    • Focuses on packetization and the reliability of transport.

  • Internet Protocol (IP) Address

    • A logical numeric address assigned to every node on a network.
    • It is assigned by a Dynamic Host Configuration Protocol (DHCP).

  • Virtual Private Network (VPN)

    • Creates encrypted tunnels over untrusted networks to ensure secure data transmission.

Network Performance, Capacity, and Data Management

  • Bandwidth

    • The maximum rate at which data can be transferred at any one time.
    • Measured in Hertz (HzHz) or bits per second.

  • Speed

    • The specific length of time it takes for data to transfer over a network.

  • Latency

    • The delay in how data is transmitted between points.

  • Data Compression

    • The process of reducing a file's size to increase efficiency, save space, and increase transmission speed.
    • Lossy Compression: Permanently reduces file size by removing data. Examples: JPEG (images), MP4 (video), MP3 (audio).
    • Lossless Compression: Reduces file size without losing any information; the data can be returned to its original size. Examples: PNG (images), ZIP (file archives).

  • Content Delivery Networks (CDNs) and Adaptive Streaming

    • Technologies used to manage high traffic and provide smooth media playback, such as adjusting video quality when data slows down.

  • Net Neutrality vs. Net Partiality

    • Net Neutrality: The ethical principle that all internet traffic should be treated equally by ISPs.
    • Net Partiality: Preferential treatment, throttling, or "zero-rating" for certain content or corporations over others.

Cyber Security, Threats, and Defensive Mechanisms

  • Authentication

    • The process of proving your identity.
    • Methods include usernames and passwords.
    • Multi-Factor Authentication (MFA): Using two or more methods, such as physical tokens, text messages, PINs, or biometric measurements (faceprints).

  • Network Attacks

    • Phishing: Sending fraudulent messages to trick users into revealing sensitive information.
    • Social Engineering: Using fraud to trick users into sharing passwords or secure info.
    • Hacking: Gaining unauthorized access to a computer or network.
    • Viruses: Malware comprised of code that spreads across networks, often attached to legitimate programs.
    • Ransomware: Malware that locks a user out of their device and demands a ransom for access.
    • DDoS (Distributed Denial of Service) Attacks: Overwhelming a network with demand using botnets (networks of infected computers) to prevent legitimate users from accessing it.

  • Network Risks

    • Identity Theft: Specifically stealing personal information for fraud or financial benefit (impersonation).
    • Data Breaches: Unauthorized release of secure information.
    • Trolling and Anonymity: Anonymity allows for privacy and safety but also enables harassment and internet trolls.

Internet Services, Entities, and Historical Evolution

  • Providers

    • Internet Service Provider (ISP): A company providing internet access and related services like web hosting and domain registration.
    • Mobile Service Provider (MSP): Also known as mobile carriers or operators; they offer cellular connections.

  • VoIP (Voice over Internet Protocol)

    • Software that allows voice calls over a broadband internet connection using digital packets.
    • Examples: Discord, Skype, WhatsApp, FaceTime.

  • Internet vs. World Wide Web (WWW)

    • Internet: The global connection of networks linking users worldwide.
    • WWW: The collection of websites and services hosted on web servers, identified by URLs.
    • Core Web Technologies: URL, HTTP/HTTPS, and HTML.

  • Internet of Things (IoT)

    • Internet-connected devices equipped with sensors to collect and share data.
    • Includes smart appliances, autonomous vehicles, and jet engines.
    • Focuses on automation and efficiency but raises concerns regarding operability, security, and surveillance.

  • Surveillance Technologies

    • Includes CCTV, facial recognition, government monitoring, and drones.
    • Represents a conflict between security and privacy, or transparency and control.

  • Timeline and Evolution

    • 19691969 onwards: Development began with ARAPNET and TCP/IP (started by Stanford for knowledge sharing).
    • 1990s1990\text{s}: The internet became popularized.
    • Web 1.0: Era of static pages.
    • Web 2.0: Era of social media and user-generated content.
    • Web 3.0: Future/current era featuring the semantic web, decentralized systems, AI integration, and IoT.