What open and closed mean
A closed port is not necessarily a problem, it usually means good security: nothing on your network is accepting outside connections there. An open port means a service is reachable from the internet, which is expected for a web server on 80 and 443 but worth investigating on a home connection, especially SSH (22), RDP (3389) or SMB (445).
Why we only scan your own IP
Scanning someone else's address without permission is intrusive and, in some places, illegal. This tool fixes the target to your own connection so it stays a safe self-diagnostic. To learn more about your connection, run a full IP lookup or check for VPN and proxy signals.