On the internet every device has an IP address. This address is used for all communications between any two devices. As data flows over the internet the IP address is used to route it to its destination.
Every packet of information also has a port number. The port number has nothing to do with getting the packet to its destination. The port number is used to direct the data once it arrives at its final destination.
This works well until you add a router. A router breaks this system by hiding IP addresses from the internet. A port forward in a router is a way of getting devices to talk again as if the router was not there. Both the destination IP address and port number are required to set up a port forward.
To find the port numbers for a sprcific game or application check out our Port List.
Open Port vs. Closed Port
An open port requires a forward in your router and a listening device or app. Having an open port means that the listening device or app can receive data from the internet.
A closed port is a port that cannot accept an incoming connection. This is the default for all ports when you have a router. Your router automatically keeps all of your ports closed for you by actively rejecting the incoming connection or simply dropping the connection or packet. Your router has no way of knowing which computer or device on your network the incoming packet is destined for. A port forward tells your router which device should receive the incoming connection request.
Is Port Forwarding Safe?
Having an open port sounds scary, right? Is it safe to forward ports in your router? Sometimes yes, but oftentimes no. It really depends on which device or app you are forwarding ports to.
When you forward a port to a device, you are putting your trust in the manufacturer of that device. Have they closed all of the security holes? Who knows. Recent news has told us that many manufacturers are lax in their security. The best advice is, the bigger and more recognizable the brand name, the more likely they are to be secure.
Gaming consoles tend to be very secure while inexpensive security cameras seem to have vulnerabilities popping up every week. For any device that you are going to forward ports to, make sure that you change your password from the default password.
The risk in having an open port to a camera or DVR is the ability for hackers to access that particular device. Even worse, they may be able to access your network through that device.
The risk is the highest if you have an open port on a computer. Forwarding ports for Minecraft and torrents is pretty safe, but if you forward a port to a web server, you had better know what you are doing.
Visit our guide Is Portforwarding Safe? for more details about forwarding ports and internet safety.
How Do I Open a Port?
When you open a port, you have to set up a port forward in your router. For help with port forwarding, find your router in our List of Routers and then follow the step-by-step instructions in our guide.
Would you rather have us open the port? If you want to just open ports with a click of a button take a look at Network Utilities. This software opens the ports you want and closes the ports you don't want with just the click of a button.
Check for Open Ports
To check if your ports are open simply use our Port Checker. Our port checking tool is better than the others out there because we don't make assumptions about applications you may be using. Our Port Checker tool uses a local application to see if the port is listening. Port Checker is part of our Network Utilities bundle of software tools.