Nmap (TCP-connect)
Polite TCP-connect port scan of a single public host (max 128 ports) with optional banner grab.
Port states
- open
- — TCP handshake completed; a service is listening on that port.
- closed
- — host actively refused the connection (RST / ECONNREFUSED). The host is reachable; nothing is listening on that port.
- filtered
- — no response before the timeout. A firewall is most likely dropping the probe; the port's true state can't be determined.