Nmap is the industry standard for network port discovery. This tool runs a default nmap scan from our cloud — that means the scan originates from our IP, not yours, and no software is installed on your machine. Results stream live to your browser.
Type a hostname or IP and submit. The scanner probes the most common 1000 TCP ports and reports each as open, closed or filtered, along with the service banner when identifiable.
Reading the output
- open — the port is accepting connections. That service is reachable from the public internet.
- closed — the host is up but nothing is listening on that port.
- filtered — a firewall or packet filter is silently dropping the probe.
- Service column — educated guess based on the port number (e.g. 80 → http). Doesn't confirm the service, just names what usually runs there.
FAQ
Is it legal to scan someone else's server? Port scanning your own infrastructure is always fine. Scanning third-party systems without authorisation is a grey area and can be unlawful in some jurisdictions — stick to systems you own or have written consent to test.
What ports are scanned? The default 1000 most-common TCP ports. UDP and full 65k port sweeps are not part of the free scan.
Why are all ports filtered? A firewall in front of the host is blocking our probe. The host is likely up but hidden behind a perimeter filter.