Ethical Hacking · 5 min
Port Scanning
Reading service states without overreading them
This lesson explains the concept, then checks your understanding in a short interactive exercise.
What a port scan checks
A port is a numbered communication channel a system can use for network services. Scanning checks whether a system responds on a given port, and classifies the result into one of three states.
- Open — something is listening and responded
- Closed — reachable, but nothing is listening there
- Filtered — a firewall or filter is blocking the probe
A port number is a hint, not a guarantee
Port 80 is conventionally used for HTTP, and 443 for HTTPS — but any service can be configured to listen on any port. The number is a strong hint, not a proof of what's actually running.
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