You use port forwarding every time you access the internet, but do you really know how it works? Read on to learn about how to set up port forwarding and ensure that your ports are protected.

It’s a crucial connectivity feature that allows you to access servers and devices from any location.

Also referred to as port mapping or port tunneling, port forwarding is a crucial connectivity feature that allows you to access servers and devices from any location. It is a technique that is used to redirect ports (computer signals) between local networks (LAN computers) and the internet (remote computers). The port forwarding process intercepts data traffic to access a computer’s IP combination before redirecting it to a different IP combination; the redirection is achieved by using hardware components like proxy servers, firewalls or routers. Proxy programs and VPNs can also be used.

The purpose of port forwarding

Although it may sound complicated, port forwarding is an ideal way to preserve public IP addresses. Its main purpose is to protect clients and servers from unwanted access by hiding servers and their available services on any given network, as well as limiting access to and from the network.

It is designed to offer absolute transparency to end users, while also adding an extra security layer to relevant networks.

As such, its purpose is to prevent unwanted network traffic and allow multiple computers to share an internet connection.

The role of ports in port forwarding

The ports that facilitate port forwarding can be likened to mail sorting tubes, only on a computer. When data packets are sent to your PC, its operating system must look at the port number the packets are directed to. There are around 65,000 ports available, and each port corresponds to a different application.

Some of the ports are fixed and operate under pre-determined standards that allow core applications to communicate effectively across the globe. For instance:

  • port 80 is the designated standard port for Apache HTTP traffic,
  • incoming POP3 emails are handled by port 110,
  • SMTP outgoing emails use port 25.

To ensure security and prevent malicious requests from accessing core services running on a computer, all ports are obstructed by default on routers. As such, a computer must direct the router to forward a specific port before allowing any data to be sent from the internet to an internal computer. This means that if the router comes across packets destined for particular ports, it forwards them to their specified local machines. In light of this, the UPnP protocol was developed to facilitate hassle-free port requests and the automatic set-up of port forwarding rules making it invisible. But is port forwarding safe?

The dangers of port forwarding

The technology behind port forwarding is designed to trigger a destination machine to view incoming data packets as originating from a router as opposed to the original machine that sent them out.

Port forwarding can allow any machine in the world to connect to a forwarded port at will, which makes the network insecure.

This means that port forwarding can allow any machine in the world to connect to a forwarded port at will, which makes the network insecure. However, using a VPN and port forwarding simultaneously protects you from this danger. Your servers and devices remain protected from unauthorised access, and the activities remain hidden from all types of hackers and cyber spies.

Using a VPN and port forwarding simultaneously protects you from this danger.

Port forwarding and VPNs

VPNs allow clients to access a private local area network (LAN) as though they were connected to its respective website in a bid to guarantee higher security levels through procedures like password verification and encryption.

VPN port forwarding guarantees users a restriction-free internet connection.

Most VPN services utilise a NAT firewall to protect their clients from malicious connections, as well as allow them to modify their IP information securely. VPN port forwarding reroutes incoming connections to bypass the NAT firewall. Hence, it is ideal for boosting torrent speeds, allowing remote access to PCs, and accessing private games or media servers on your LAN.

How does port forwarding work?

To send requests online, data packets are created and sent over the internet. The data packets hold your request details, which include information such as the destination of your device or computer. A network router examines an IP packet’s header before sending it to the appropriate destination or its linked interface.

In port forwarding, however, intercepting applications read data packet headers, note their requested destination and then rewrite their header information before forwarding it to another server or computer (secondary host destination).

In most cases, the secondary host destination can be a different server that uses another port or IP address, or even a totally different combination of the same. When using a proxy or VPN, secondary destinations are servers offered by the provider that are used to mask the original IP address. To set up port forwarding, you name a port, give it the start and stop port numbers, and then type the IP address of the receiving device. For instance, data coming from port 5000 is redirected to port 5000 on your network’s local computer.

Security issues

Through port tunnelling, users can forward all types of ports according to their needs. But is port forwarding dangerous? It has been dubbed a big security issue, especially in the era of the internet of things. With the manual port forwarding setup, your online communications are not always as safe as you may imagine.

You are exposed to a myriad number of vulnerabilities, especially if you use it without having extra security measures in place.

However, the level of safety is determined by your activities. For instance, if you are using it to access a game console, then it is completely safe.

What is it used for?

Port forwarding allows network administrators to use a single IP address to handle all their external communications over the internet, while dedicating different servers using different ports and IPs to internal tasks.

It is useful for home network users who run gaming or web servers from a single network.

Common applications include testing network ports, enhancing resistance against DDoS attacks, emailing clients securely and recovering your lost router password. It also allows access to your server, laptop or PC from any location for torrenting and remote access to your computer, among other uses.

A network administrator can set up a public IP address on a specific router with the aim of translating requests to the optimal server via the internal network. By using a single IP address to accomplish different tasks, while dropping all the traffic that may be unrelated to the services offered via the firewall, the network administrator can effectively hide the services running on their network from the outside world. In this case, port forwarding is used to secure network services from malicious attacks and unauthorized access, which is important as the internet of things grows.

Variations of port forwarding

There are two main variations of port forwarding:

  • double port forwarding,
  • reverse port forwarding.

Double port forwarding refers to computer networking with the help of multiple routers; it is essentially port forwarding through two routers, which tends to be more complex than port forwarding via one router. It means that ports from one router are forwarded to another router or gateway containing an external IP address. The gateway or router then responds by forwarding the data to a host on a specified local area network (LAN). This allows one router to forward all the incoming data traffic to the other router.

Reverse port forwarding also referred to as reverse port tunnelling, is made up of a session server and session client. The session server is used to connect to the session port, while the session client is used to connect to the session server components. For instance, when a secure connection is established, the session server triggers the port to be forwarded. Once the connection is established, it is forwarded to the session client with a destination that is accessible to the session client. This mainly happens when access must be made to ports behind a firewall preventing access.

Setting up port forwarding

Specific instructions on how to set up port forwarding can differ among routers or brands. Therefore, this is a general overview of how to set up port forwarding.

  1. First, open the port forwarding settings panel after logging in to your router.
  2. You will get a list of empty port configurations; choose one configuration and enter your preferred internal and external port numbers.
  3. After setting the ports, enter the local IP address of the device the port is required to connect to on your local computer. The local computer address should differ from the router’s IP address.

The addresses should be different because the router’s job is to hide your computer’s IP address under a single public IP address that is assigned to the router. Once the router port records all the crucial data packet information, it redirects all requests that are sent to the port straight to your local computer or preferred device without revealing its unique IP address. For instance, if your IP address is 122.465.879 and you choose port 3565, the request is forwarded to the address 122.465.879.3665. This protects your identity and prevents malicious hackers from identifying your open ports.

A summary

The most crucial aspect to remember when using port forwarding is security. As discussed above, port forwarding passes all your data through less secure channels, potentially exposing data packets to malicious hackers. However, by using a VPN, data packets are encrypted to make their information hard to interpret if it is intercepted.

Note that a VPN may require additional steps to connect to networks and offer the much-needed superior security. Port forwarding is used to ensure that all internet users carry out their routine online activities effectively. Therefore, if you want to enjoy healthy data exchange over the internet, you must consider port forwarding.