Open Port Checker
Set up a game server, a camera or remote access and it will not connect? Check whether the port is actually open on your connection. This tool tests your own public address only.
What an open port means
A port is a numbered door on your connection. A program listens on a port, and other computers reach it by connecting to your public IP address and that port number. For something outside your home to reach a program inside, the port has to be forwarded on your router and allowed by any firewall. This tool tries to connect to the port you choose on your own public address from our server and tells you what happened.
- Open: something accepted the connection.
- Closed: your connection answered but refused it, so nothing is listening there or the router rejects it.
- No answer: the connection timed out. A firewall or router is dropping the traffic, or the port is not forwarded.
If your port shows closed or no answer
- Check that the program or server is running and listening on that port.
- Add a port forward in your router to the device’s local address, using the same port.
- Allow the program through the firewall on the device.
- Make sure your provider gives you a public address. Some connections share one address between customers (CGNAT), which blocks incoming connections; ask your provider about a public address.
- Remember a VPN changes the address that is tested. Turn it off for this check.
Be careful with open ports
Only open ports for services you need, keep that software updated, and use strong passwords. Remote Desktop (port 3389) and similar services open to the whole internet are common targets. Close ports you do not use. If you are unsure, an open port you did not expect is worth closing in your router.
About this tool
For safety this tool only tests the public address of the connection you are using. You cannot type another address, so it cannot be used to scan other people’s networks. One port is checked per request, and requests are limited to keep the service fair. We do not store the result. If you want to know your address first, see What is my IP address?
Frequently asked questions
How do I check if a port is open?
Enter the port number above and press Check port. The tool tries to connect to that port on your public IP address and tells you whether it is open, closed or got no answer.
Why does my port show closed even after port forwarding?
The program may not be running or not listening on that port, a firewall on the device may block it, or your provider may share one public address between customers, which blocks incoming connections.
Can I check another person's or server's ports with this tool?
No. It only tests the public address of the connection you are using, so it cannot be used to scan other networks.
What ports do Minecraft and Plex use?
Minecraft Java servers use port 25565 by default and Plex Media Server uses 32400. Both are in the quick-pick list above.
Is an open port dangerous?
Only if the service behind it is unneeded, out of date or poorly protected. Open only the ports you need, keep software updated and close the rest in your router.
Related tools and guides
- What is my IP address?: your public address.
- VPN speed test: what your VPN costs you.
- Internet speed for gaming: what games really need.
- All tools: every CHECKiOX tool in one place.