How to use
- Enter a domain or IP. To test your own connection, click Use my IP.
- Enter ports, or click the common ports below to add them — up to 10 at a time.
- Click Check to see each port's status and connection time.
Options explained
- Open
- The TCP connection succeeded, so a program is listening and the firewall allows it.
- Closed (connection refused)
- The host is reachable but nothing listens on that port, or a firewall rejects the connection.
- No response
- Nothing came back within 3 seconds. A security group or firewall is usually dropping the request, or the host is offline.
Reading the results
Each row shows the port, the service usually found on it, the status and the time the connection attempt took. Besides Open, Closed (connection refused) and No response (likely filtered by a firewall), two more statuses can appear:
- Unreachable: the connection failed for another reason, such as no route to the host.
- Cannot test: port 25 is skipped because outbound connections on it are blocked on our side.
You can type a bare domain, an IP address or paste a full address; the protocol, path and port are stripped. Ports are whole numbers from 1 to 65535, separated by commas or spaces, and duplicates are removed. A domain is looked up once and IPv4 is preferred. If the name resolves to a private address, the check is refused.
The Common ports buttons add or remove these ports:
| Port | Service |
|---|---|
| 21 | FTP |
| 22 | SSH |
| 80 | HTTP |
| 443 | HTTPS |
| 3306 | MySQL |
| 3389 | RDP |
| 5432 | PostgreSQL |
| 6379 | Redis |
| 8080 | HTTP (alternate) |
| 27017 | MongoDB |
Frequently asked questions
It works locally but shows No response here — why?
Check that the cloud security group and the OS firewall (firewalld, ufw, Windows Firewall) allow the port. A service listening only on 127.0.0.1 is reachable only from the machine itself; make it listen on 0.0.0.0.
Why can't port 25 be tested?
Our server runs on Alibaba Cloud, which blocks outbound connections to port 25 by default, so there is no meaningful result.
Does it scan every port?
No. It tests only the ports you enter, up to 10 at a time, with a TCP handshake and no data sent, and checks are rate-limited. Private addresses and UDP ports are not supported.
Privacy
This tool needs our server: what you enter or upload is sent over HTTPS, processed and then discarded, never stored. Server access logs record IP addresses and request URLs, used only to prevent abuse.