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🛡️ Networking Fundamentals – Basic Notes

Introduction

1. What is Networking?

Networking is the practice of connecting computers and other devices to share resources like files, printers, and internet access. It forms the backbone of modern communication.

2. What is a Network?

A network is a group of two or more devices (like computers, phones, servers, etc.) connected together to share information, resources, and services.

📡 3. Types of Networks

  • LAN (Local Area Network): Small area (e.g., home, office)
  • WAN (Wide Area Network): Large geographic area (e.g., Internet)
  • MAN (Metropolitan Area Network): Covers a city
  • PAN (Personal Area Network): Short-range, for personal devices (e.g., Bluetooth)

🌐 4. Basic Networking Devices

Device Function Cyber Security Role
Router Connects multiple networks, routes traffic Can include firewalls and VPN support to secure traffic between networks
Switch Connects devices within a LAN Offers features like VLANs for network segmentation, improving security
Hub Basic version of a switch, broadcasts to all Insecure—makes networks vulnerable to packet sniffing (deprecated)
Firewall Controls incoming and outgoing traffic Prevents unauthorized access and blocks malicious traffic
Modem Converts analog signals to digital and vice versa Entry point to the internet; needs to be secured
WAP Provides wireless access to a wired network Must use strong encryption (e.g., WPA3)
VPN Encrypts network connections over public or untrusted networks Provides confidentiality, integrity, and anonymity for remote users

🔗 5. Network Topologies

Topology Description Pros Cons
Bus Single cable backbone Easy to install Difficult troubleshooting
Star Devices connect to a central hub Easy to manage Central hub failure risk
Mesh Devices interconnected High reliability Expensive, complex
Hybrid Mix of two or more topologies Scalable Complex design

📶 6. Network Models

A. OSI Model (7 Layers)

Layer Function Cybersecurity Concerns
Physical Hardware transmission Cable tapping, physical damage
Data Link MAC addressing, switching MAC spoofing
Network IP addressing, routing IP spoofing, DDoS
Transport TCP/UDP, segmentation Port scanning, session hijacking
Session Manages sessions Session hijacking
Presentation Data translation & encryption Weak encryption, data leaks
Application Interfaces for user apps Application attacks, malware

B. TCP/IP Model (4 Layers)

  1. Network Interface
  2. Internet
  3. Transport
  4. Application

🧪 7. Common Protocols

Protocol Port Use Case Security Concerns
HTTP 80 Web browsing No encryption
HTTPS 443 Secure web SSL/TLS needed
FTP 21 File transfers Sends passwords in plain text
SSH 22 Secure remote access Key/password brute force
DNS 53 Resolves domain names DNS spoofing

🛠️ 8. Common Network Attacks

Attack Type Description Example
DDoS Flooding a server with traffic to crash it Botnet attacks
MITM Intercepting communication between two parties ARP spoofing
Phishing Social engineering to steal data Fake login page

🔐 9. IP Addressing

IPv4

  • 32-bit address, e.g., 192.168.1.1
  • Classes: A (large), B, C (small)
  • Private IP ranges (non-routable on internet):
    • 10.0.0.0 – 10.255.255.255
    • 172.16.0.0 – 172.31.255.255
    • 192.168.0.0 – 192.168.255.255

IPv6

  • 128-bit address, e.g., 2001:0db8:85a3::8a2e:0370:7334
  • Designed due to IPv4 exhaustion

Subnetting

Subnetting breaks a large network into smaller segments for security and efficiency. It helps with isolation, access control, and traffic management.

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