Článek
Nmap is not magic — it is a tool that speaks the same language every device on the internet understands. If you don’t know those languages, you won’t understand what Nmap is telling you, why certain scans fail, or what the results actually mean.
Think of this part as the foundation. Every command you’ll learn later makes complete sense once you’ve absorbed these concepts.
What Are Network Protocols?
In computer networks, communication happens through protocols.
A protocol is a set of rules that defines how data is transmitted between devices. These rules ensure that completely different systems — like a Linux server and a Windows machine — can still communicate without confusion.
Data is not sent all at once. It is broken into smaller units called packets.
Each packet contains:
- Header → Metadata (source, destination, flags, TTL, etc.)
- Payload → The actual data being transmitted
The header ensures the packet reaches the right destination and is interpreted correctly.
The OSI Model — The 7-Layer Cake
The OSI (Open Systems Interconnection) model was created by the International Organization for Standardization to give us a shared vocabulary for describing how network communication works. It divides the entire process into seven abstraction layers, each with a specific job.
When you run Nmap, you’re mostly operating at Layer 3 (Network) and Layer 4 (Transport) — but understanding all seven layers will make you a sharper thinker.
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