Free tool · Port scanner
Online Port Scanner
Check which common ports are open on a target you own — from the outside in, the same view an attacker has. No install, no account, results in seconds.
How to read the results
Open
A service accepted the connection. This is exposure — not automatically a problem, but it should be intentional and known.
Closed
The host answered that nothing is listening on that port. Good news, and confirmation the scan reached the host.
Filtered
No answer — a firewall silently dropped the probe. Usually what correct configuration looks like, though it can also mask a downed path.
The ports we check, and why they matter
| Port | Service |
|---|---|
| 21 | FTP |
| 22 | SSH |
| 25 | SMTP |
| 53 | DNS |
| 80 | HTTP |
| 110 | POP3 |
| 143 | IMAP |
| 443 | HTTPS |
| 445 | SMB |
| 3306 | MySQL |
| 3389 | RDP |
| 8080 | HTTP-alt |
| 8443 | HTTPS-alt |
What this tool doesn't do
A common-port check is a surface map, not an assessment. It checks 13 ports, not all 65,535 — a service on an unusual port stays invisible. It doesn't fingerprint the software behind an open port, so it can't match against known CVEs. And it says nothing about the web application behind port 443, which is where most real-world exposure lives.
The pipeline that should follow a port scan: full-range Nmap with service version detection, Nuclei template scans for known CVEs and exposures against what was found, and OWASP ZAP active testing on web targets. Our port scanning guide and Nmap vs Nuclei vs ZAP comparison explain how the layers fit together.
Found something open? Run the full scan.
VulnScanners runs that entire pipeline — hosted, on clean isolated infrastructure, with target validation and scheduling built in — and turns the output into a client-ready PDF report. Priced per scan, no subscription.
FAQ
Is this port scanner free?
Yes — the common-port check is completely free and requires no account. Scans are rate-limited and logged.
Which ports does it check?
13 of the most commonly exposed service ports: 21, 22, 25, 53, 80, 110, 143, 443, 445, 3306, 3389, 8080, and 8443. A full scan covers all 65,535 ports with service version detection.
What do open, closed, and filtered mean?
Open means a service accepted the connection. Closed means the host answered that nothing is listening on that port. Filtered means no answer came back at all — typically a firewall silently dropping the probe.
Is port scanning legal?
Scanning systems you own or have written authorization to test is standard security practice. Scanning systems you don't have permission to test is illegal in most jurisdictions. This tool requires you to confirm authorization before every scan.
Why does the scan come from your servers?
Scanning from a remote network shows your external attack surface — what an attacker on the internet can see — rather than your internal view from behind your own firewall.