Port is a communication endpoint in a networking system. You can recognize a port by its 16-bit unsigned number and each of them specifies a particular process for a different network service. It is always associated with an IP address and a communication protocol. Each of the port sends its data through a networking device called a router, which is responsible for transferring data packets between computer networks.
Data between network systems is sent from one port to another at the end of a communication. In a network system, when you want to redirect that data to another computer system, one uses port forwarding. The reasons for forwarding the communication to another end can be a firewall on the network, router or proxy server. A firewall is a security system that comes with predetermined rules. It monitors and controls incoming and outgoing traffic on the network.
Port forwarding is a great method to preserve public addresses and protect your servers and clients from any unwanted access. It's an extra layer of security for the network. In port forwarding, the host computer which receives the IP packet makes the note of its destination. It reads the header, rewrites it and redirects it to another computer. The second computer that receives the packet may have a different IP address but the same port, a different port or the same IP address. It may also have a combination of a different IP address and a different port number.
All the traffic on a network passes through ports, each meant for a specific purpose. Opening a port and choosing a device on the network to send the incoming messages is called port forwarding. Following are the ways to setup port forwarding:
You can assign a fixed IP address to a computer on your local network. This way, you won't have to change the port forwarding each time it gets a new IP. For this, you need to the command prompt on your windows device and note down the results of the 'ipconfig' command. You can then open the properties of your connection in the Network center and set up your static IP address. You can also access your router as an admin and "reserve" an IP address under its list of devices.
After you've configured the static IP address, you can set up the port forwarding settings on your router. You need to access your router as an admin and check for port forwarding settings. It could be under categories like network, wireless or advanced. After that, you need to fill in the number of the port that you want to forward. Fill in the start and end boxes for port ranges. You can check online which ports you need open for your service. You will then have to choose a protocol (TCP, UDP or both), fill in the static IP address and turn port forwarding on. Most routers have similar ways of port forwarding, but you can find specific instructions for your Mikrotik, Tplink, Netgear router or Google wifi as well.
Check for open ports: It's possible that even after setting up port forwarding, the program is unable to access the port due to a firewall. Therefore, you need to see on an online port checker tool if the port is open or not. If it isn't, you may have to change its status or reconfigure your settings to a different port.
Every application on the internet requires an open port to run properly. For example, a gamer playing a video game online needs to communicate with other players, someone using torrent needs open ports to upload files, and even instant messaging service works through a specific port.
So, if your program on the internet is unable to work despite the correct setup, the required port on your router might be closed. Therefore, you will have to open the port on your router and setup port forwarding to redirect the requests of your service to the right device. You can also set up port range forwarding where you forward an entire range of ports for a specific task like a video game.
Port forwarding is a technique of redirecting the data received on one of the ports to another. If the port forwarding needs to reach multiple local computers at the same time, a dynamic technique called port triggering is used. Theoretically, both the techniques sound similar as they both reroute traffic and need to be configured on a router. However, they are different due to their use of open and closed ports. In port forwarding, a port is left open continuously while it is only open for a specific period in port triggering. Thus, port triggering is more secure as it limits the time in which a port is open.
Virtual Private Networks also use port forwarding techniques to make sure that their client doesn't interact openly with the internet. In VPN port forwarding, the incoming connections bypass the NAT firewall so that the connection speed is higher. VPN port forwarding helps increase the speed of the torrents and also allows you to access your device when you're not home. You can either prefer static or dynamic port forwarding. In static forwarding, you will have a specific range of ports available all the time but in dynamic, the numbers of the port will keep changing.