快速参考
About Port Scanner
Checking if a specific port is open on a server or IP address is a fundamental network troubleshooting step. Our free online Port Scanner allows you to quickly verify the status of common ports from an external perspective.
How It Works
The tool sends a connection request from our server to the target IP address or hostname on the specified port. If the connection is successful, the port is marked as 'Open'. If the connection times out or is refused, it is marked as 'Closed' or 'Filtered'.
Common Use Cases
- Verifying that a newly configured web server (Port 80/443) is accessible from the internet
- Checking if a game server or custom application port is open
- Troubleshooting firewall rules and network routing issues
- Performing basic security audits to ensure sensitive ports (like 22 or 3389) are closed
Frequently Asked Questions
A 'Filtered' status usually means that a firewall is silently dropping the connection requests, so our scanner cannot determine if the port is actually open or closed behind the firewall.
You can scan public IP addresses and hostnames. However, you cannot scan internal/private IP addresses (like 192.168.x.x) because our external server cannot reach your local network.