TCP Port Checker
Test TCP connectivity to common public ports with accurate status labels—not arbitrary scanning.
Common ports (allowlist only):
Approved public TCP destinations only—not a port scanner.
Run a check to see TCP connectivity from the server origin.
How to use
- Enter a public hostname.
- Select an allowed port.
- Run Check Port and read the status explanation.
Examples
HTTPS port
Test port 443 to see if TCP connects—application health is separate.
SSH bastion
Test port 22 when diagnosing firewall rules (public hosts only).
Allowlisted ports only. Not a scanner. Probes originate from the server.
FAQ
- Can I scan all ports?
- No. Only documented common ports are permitted.
- Does refused mean closed?
- Usually, but filtering and middleboxes can produce other failures labeled separately.