What "open" and "closed" mean
Open: something on your network answered on that port, so the forwarding rule and the program are working.Closed: nothing answered. Either no rule forwards that port, a firewall blocks it, the program is not running, or your provider does not give you a public IPv4 address.
Port forwarding not working? Check these in order
- The program is running and listening on the device and port you forwarded.
- The forwarding rule points to the device's current local IP. Give that device a fixed (reserved) local IP in the router so the rule does not break.
- The device firewall (Windows Defender Firewall, macOS firewall, antivirus) allows incoming connections on that port.
- Double NAT: if your router's WAN address differs from the IP shown above, there is another router or modem in front of it.
- CGNAT: if your router's WAN address starts with
100.64–100.127, your provider shares one public IPv4 among many customers and incoming connections cannot reach you. Ask for a public IP or use IPv6.
Common ports
| Port | Used by |
|---|---|
| 21 | FTP |
| 22 | SSH |
| 53 | DNS |
| 80 | HTTP |
| 443 | HTTPS |
| 3389 | Remote Desktop (RDP) |
| 25565 | Minecraft server |
| 27015 | Steam / Source games |
| 3074 | Xbox Live |
| 8080 | HTTP alternate / proxies |
| 5900 | VNC |
| 32400 | Plex Media Server |