Online Port Scanner
Check which common ports are open or closed on a host and use the results to verify firewall behavior, confirm services are listening, or troubleshoot connectivity issues.
Check common ports without extra setup.
Useful when reviewing exposed services.
See the host from a public network perspective.
What this port scanner shows
This tool checks a set of common ports on a host and helps you see which ones appear open or closed from an outside perspective.
That makes it useful for developers, hosting customers, support teams, security teams, and anyone confirming whether a service is exposed as expected.
Why it matters
Unexpected open ports can create security risk, while closed or filtered ports can explain why a service is unreachable.
What is port scanning?
A port scanner attempts to connect to specific TCP ports on a target host to determine whether they are open, closed, or filtered by a firewall.
Common ports have well-known services: port 80 (HTTP), 443 (HTTPS), 22 (SSH), 21 (FTP), 25 (SMTP), 3306 (MySQL). Finding unexpected open ports on your server can help identify misconfigurations or security risks.
Is it legal to scan ports?
Scanning your own servers is always fine. Scanning third-party hosts without permission may violate their terms of service or local laws. Only use this tool on hosts you own or have explicit permission to test.
Understanding port scan results
- Open — the port is listening and accepting connections. A service is active on that port.
- Closed — the port is reachable, but no service is listening. The TCP connection was refused.
- Filtered — a firewall or network filter is blocking the connection attempt. The port may be open, but we cannot determine its state.
- Timeout — no response was received within the timeout period. Often indicates heavy filtering or a routing problem.
Common ports and services
21 — FTP (File Transfer)22 — SSH (Secure Shell)25 — SMTP (Email)53 — DNS (Domain Names)80 — HTTP (Web)443 — HTTPS (Secure Web)3306 — MySQL (Database)5432 — PostgreSQL (Database)Why use this tool?
- Security audits — verify only intended ports are exposed on your server.
- Troubleshooting — confirm a service is actually listening on the expected port.
- Firewall verification — test that your firewall rules are working as configured.
- Connectivity checks — diagnose why you cannot connect to a service on a remote host.
Frequently asked questions
Why do I get a timeout?
Timeouts usually mean the host is not reachable or a firewall is blocking the scan attempt.
Can I scan non-standard ports?
This tool focuses on common ports. For deeper custom scanning, a local tool like nmap is more suitable.
What if all ports appear filtered?
That usually suggests firewall filtering or network controls are blocking scan attempts.
What should I use next?
Ping, traceroute, and HTTP checks can help explain whether the host is reachable and where connectivity problems may exist.