🔗 Link to the Room

🏷️ Table of Contents

1. What is Networking?
   
2. What is the Internet?
   2.1 History of the Internet
   2.2 Structure of the Internet
   
3. Identifying Devices on a Network
   3.1 Device Identification Analogy
   3.2 IP Addresses
   3.3 Public IP Address
   3.4 IPv4 vs IPv6
   3.5 MAC Addresses
   3.6 MAC Address Spoofing
   3.7 MAC Filtering in Public Wi‑Fi
   
4. Ping (ICMP)
   

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📚 Study Notes

What is Networking?

• At its most basic level, a network is simply things that are connected.

• A helpful way to think about this is through everyday examples, such as a friendship group, where people are connected by shared interests, activities, or goals.

• Networks exist everywhere, not just in computing.
• For example:
  • A city’s public transportation system
  • National electricity and power grids
  • Postal systems for sending letters and parcels
  • Social interactions, such as meeting and greeting neighbours

• All of these systems involve connected entities working together to share resources or information.

• In computing, networking follows the same concept but applies it to technological devices.

• Examples of networked devices include laptops and smartphones, servers and routers, security cameras and traffic lights, industrial and agricultural systems

• A computer network can consist of as few as two devices or billions of devices connected globally

• Devices are networked so they can communicate, share data, and access resources.

• Networks are deeply integrated into modern life, supporting systems such as weather data collection, power distribution, traffic management or communication and information access

• Because networks underpin so much of today’s infrastructure, understanding networking is essential in cybersecurity.
• Securing systems requires knowing how devices connect, communicate, and interact.

 

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❓What is the key term for devices that are connected together?

Network

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What is the Internet?

• The Internet is essentially one giant network made up of many smaller networks connected together.

 

History of the Internet

• Late 1960s: The ARPANET project, funded by the U.S. Department of Defense, created the first documented network
• 1989: Tim Berners-Lee invented the World Wide Web (WWW), transforming the Internet into a global system for storing and sharing information
• Since then, the Internet has become the vast, interconnected network we use today

 

Structure of the Internet

• The Internet is made up of private networks (smaller, individual networks) and public networks (networks connecting private networks — the Internet itself)

[!NOTE] In short, a network can be private or public, with the Internet being the largest example of a public network.

 

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❓Who invented the World Wide Web?

Tim Berners-Lee

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Identifying Devices on a Network

• For devices to communicate reliably on a network, they must be identifiable. Just like humans can be identified in more than one way, network devices also have two forms of identification.

 

Device Identification Analogy

• Devices are similar to people where name is an IP Address (can change) and fingerprint is MAC Address (hardware-based, intended to be unique)
• Both are used to identify devices, but they serve different purposes.

 

IP Addresses

• An IP (Internet Protocol) address identifies a device on a network for a period of time.
• Key Properties:
  • Written as four numbers (IPv4) separated into octets
  • Assigned through IP addressing and subnetting methods
  • Can change over time (dynamic assignment)
  • Cannot be used by more than one device at the same time within the same network
  • Follows standard networking protocols so devices can communicate consistently

 

Public IP Address

• Used to identify a network/device on the Internet
• Assigned by an Internet Service Provider (ISP)
• Usually shared by multiple devices behind a router (via NAT)
• Costs money as part of your internet service

[!IMPORTANT] Devices inside the same private network talk using private IPs Traffic going out to the Internet appears to come from the same public IP

 

IPv4 vs IPv6

 

IPv4

• Current widely used version
• Uses 32-bit addressing
• Supports about 4.29 billion addresses
• Address shortage due to massive device growth

 

IPv6

• Newer version designed to solve IPv4 exhaustion
• Uses 128-bit addressing
• Supports an extremely large number of addresses (2¹²⁸)
• More efficient and modern design
• Written in hexadecimal format

 

MAC Addresses

• A MAC (Media Access Control) address identifies a device’s physical network interface.
• Key Properties:
  • Assigned at the factory to the network interface card (NIC)
  • Intended to be globally unique
  • Acts like a hardware serial number
  • Format: 12-character hexadecimal, separated by colons, e.g. a4:c3:f0:85:ac:2d
• Structure: First half identifies the manufacturer and the second half is unique device identifier

 

MAC Address Spoofing

• Although MAC addresses are hardware-based, they can be spoofed (faked).
• MAC Spoofing means, that device pretends to use another device’s MAC address, used in both testing and attacks and can bypass weak security systems

 

[!CAUTION] If a firewall allows traffic from a specific MAC address (e.g., admin device), an attacker who spoofs that MAC address may be incorrectly trusted.

 

MAC Filtering in Public Wi‑Fi

• Some public networks (cafes, hotels, guest Wi‑Fi) use MAC-based access control:
  • Access or speed is granted per MAC address
  • Payment may unlock access for one device only
  • Changing (spoofing) a MAC address can sometimes bypass these controls if poorly implemented

 

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❓What does the term "IP" stand for?

Internet Protocol

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❓What is each section of an IP address called?

Octet

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❓How many sections (in digits) does an IPv4 address have?

4

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❓What does the term "MAC" stand for?

Media Access Control

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❓Deploy the interactive lab using the "View Site" button and spoof your MAC address to access the site. What is the flag?

THM{***_**_*********}

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Ping (ICMP)

• Ping is a basic network troubleshooting tool used to test connectivity between two devices.
• It works using ICMP (Internet Control Message Protocol).
• Ping sends an ICMP Echo Request packet to a target device and the target replies with an ICMP Echo Reply packet.
• This confirms:
  • Whether the device is reachable
  • Whether the connection is working
  • How fast packets travel between devices
• Ping Measures:
  • Round-trip time (latency) — how long packets take to go to the target and back
  • Packet success/loss — whether packets are received or dropped
  • Helps judge connection reliability and performance

• Basic command: ping <IP address or domain>

• Typical output shows packets sent/received, packet loss % and minimum / maximum / average response time (ms)

 

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❓What protcol does ping use?

ICMP

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❓What is the syntax to ping 10.10.10.10?

ping 10.10.10.10

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❓What flag do you get when you ping 8.8.8.8?

THM{*_******_***_******}

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