Open
The remote host accepted a TCP connection on that port. This does not identify the exact application or prove it is secure.
Secure public port test
Online Port Checker
Test common or custom TCP ports on a public domain or IP address and see clear connection results.
Common Ports
Select a port to add it to your scan
Only public Internet targets are allowed. Scan systems you own or are authorized to test.
How it works
Check public TCP ports safely
- 01
Enter a public target
Provide a public domain or IP address that you own or are authorized to test.
- 02
Choose the ports
Select a common preset, click ports from the reference card, or enter up to 20 comma-separated values.
- 03
Read the connection state
See whether each TCP connection was accepted, refused, timed out or could not be reached.
Understand port states
What each port result means
Closed
The target was reachable but actively refused the connection, usually because no service is listening.
Filtered
The connection timed out. A firewall or network policy may be silently dropping traffic.
Unreachable
The scanner could not reach the destination network or interface for that connection.
What does an open port mean?
It means the target accepted a TCP connection on that number. It does not prove which software answered or whether the service is safe.
Why is a port shown as filtered?
No TCP response arrived before the timeout. Firewalls commonly drop unwanted traffic without replying.
Can I scan private IP addresses?
No. The service rejects loopback, private, link-local, reserved and internal targets, including hostnames with mixed public and private DNS answers.
Which ports can I check?
You can select common ports or enter up to 20 TCP port numbers from 1 through 65535.
Why might another checker show a different result?
Firewall rules can depend on the scanner location, protocol and time. This tool tests TCP connectivity from the DevsLoad service.