Port Scanner Guide
Educational reference — DevTools does not scan ports
What is a port scan?
A port scan sends connection attempts to TCP/UDP ports on a host to learn which services are listening. Security teams use authorized scans; attackers use them for reconnaissance.
Common techniques
TCP connect scan completes the handshake. SYN scan sends half-open probes. UDP scans are slower because many ports drop packets silently. Service/version detection follows open ports.
Legal and ethical boundaries
Scan only systems you own or have written permission to test. Many jurisdictions treat unauthorized scanning as illegal access. Cloud providers may suspend accounts for probing external hosts.
Safer alternatives for developers
Use the Port Reference tool for well-known port numbers. Test local services with curl or your app health endpoint. For production, rely on internal monitoring—not ad-hoc scans from a browser.
Related DevTools
Port Reference lists IANA-style service names. HTTP Request Builder tests a single endpoint. SSL Inspector validates certificates on a known HTTPS URL.
Related tools
T-619 note: Port scanning is not implemented as an active tool; use Port Reference for port numbers and this guide for education.
About this tool
Learn about port scanning ethics and alternatives. No scanning performed. Free. Port Scanner Guide runs in the browser on DevTools. There is no signup, and your input stays on this device unless the tool explicitly performs a live network lookup.
What this tool does not do
- Port Scanner Guide is a free in-browser utility, not a hosted API. It does not keep server-side history and is not a substitute for production verification in your own stack.
How do I use this tool?
How do I use Port Scanner Guide?
Open Port Scanner Guide, enter or paste your input, and copy the result. The page works without an account.
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