🌐 Networking Basics — Understanding How Systems Communicate
Before learning about hacking or security tools, it is important to understand how computers communicate on a network.
Every cyber attack, penetration test, or security investigation begins with network understanding.
If you understand networking, you can:
• Discover systems on a network
• Identify services running on servers
• Understand how attacks move between machines
Networking knowledge is a fundamental skill in cybersecurity.
🔎 What is a Network?
A network is a group of devices connected together so they can communicate and share resources.
Examples of devices on a network:
• Computers
• Servers
• Smartphones
• Routers
• IoT devices
These devices communicate using network protocols.
📡 IP Address
An IP Address is a unique identifier assigned to each device on a network.
Example:
192.168.1.10
There are two common types of IP addresses.
Private IP
Used inside local networks.
Examples:
192.168.x.x
10.x.x.x
172.16.x.x – 172.31.x.x
Public IP
Used on the internet and assigned by an ISP.
🚪 Ports
Ports are communication endpoints used by services on a computer.
Think of an IP address as a building, and ports as doors.
Common ports:
Port Service
21 FTP
22 SSH
25 SMTP
53 DNS
80 HTTP
443 HTTPS
Attackers and security testers often scan ports to discover running services.
🔗 TCP vs UDP
Two of the most common network protocols are TCP and UDP.
TCP (Transmission Control Protocol)
• Reliable communication
• Connection-based
• Used by services like HTTP, SSH, FTP
UDP (User Datagram Protocol)
• Faster but less reliable
• No connection required
• Used by DNS, streaming, gaming
🔎 Network Discovery
One of the first steps in penetration testing is discovering devices on a network.
Example tool used in Kali Linux:
Nmap
Example command:
nmap 192.168.1.0/24
This scans the entire subnet and discovers active hosts.
🧪 Why Networking Matters for Hackers
Understanding networking allows security professional