What Is Port Forwarding and How Do You Test It?

Port forwarding tells your router to send incoming internet traffic on a specific port to a specific device inside your home network. It is what makes game servers, security cameras, Plex and remote desktop reachable from outside.

Why it is needed

Your home has one public address shared by every device, and your router uses NAT to keep the devices private. A request arriving from the internet has no idea which device it is for, so the router drops it. A port forwarding rule adds an exception: “traffic arriving on port 25565 goes to the gaming PC at 192.168.1.50”. See public vs private IP addresses for the background.

How to set it up

1. Give the device a fixed local address. Create a DHCP reservation in the router so the device keeps the same private IP.
2. Open the router's admin page. It is often 192.168.1.1 or 192.168.0.1. The login is printed on the router.
3. Find the Port Forwarding section. It may be under Advanced, NAT or Gaming.
4. Create a rule. Enter the external port, the device's private address, the internal port and the protocol (TCP, UDP or both).
5. Allow the port in the device's firewall and make sure the service is running.
6. Test it. Use our port checker to confirm the port is open from the internet.

Common ports

• 22 SSH
• 80 and 443 HTTP and HTTPS
• 3389 Remote Desktop
• 25565 Minecraft Java
• 32400 Plex
• 51820 WireGuard (UDP)

Why a port still shows as closed

• The service is not listening on that port or is bound only to localhost.
• A firewall blocks it on the device or the router.
• Double NAT. A second router, such as your provider's modem behind your own router, needs its own forwarding rule or bridge mode.
• Carrier-grade NAT. If your router's WAN address differs from the address on our IP checker, your provider shares one address between customers and inbound connections will never arrive. Ask for a public address, or use a tunnel. See why your IP address changes.
• UDP. Our checker tests TCP only, because UDP has no handshake to confirm.

Staying safe

Every open port is an entrance. Forward only what you need, keep the software behind it updated, use strong passwords or keys, and close ports you no longer use. For private services such as a home server or camera, a VPN or a tunnel service is safer than exposing a port at all.