Port Forwarding: Importance, How It Works, and How to Setup

Published on: July 22, 2024

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11 min read

Port forwarding intercepts data traffic intended for a computer's IP address or port combination and reroutes it to another IP address or port, allowing a computer or network device to contact other devices from outside the local network. By port forwarding, undesired traffic is kept off networks.

The application is often launched by the host on the target machine, but it may be run via a router, firewall, or proxy server as an intermediary. The information will reach its destination unaltered, and individuals sending data to the server won't be aware that it exists, even though the host is hiding their IP address and/or location with this technique.

We can all gain from port forwarding, provided that its precise capabilities are well understood. We've covered all there is to know about port forwarding, including its definition, uses, and advantages. You can choose whether or not to utilize port forwarding by reading this article.

• What Is Port Forwarding?

• How does Port Forwarding Work?

• Why Is Port Forwarding Important?

• Where Is Port Forwarding Used For?

• How does Port Forwarding Work in a Firewall?

• How to tell if Port Forwarding is working?

• How to Setup Port Forwarding?

  • Is it a good idea to use port forwarding?

  • Is Port Forwarding Safer than VPN?

• What is the difference between Port Forwarding and VPN?

• How Does SASE Eliminate the Need for Traditional Port Forwarding?

What is Port Forwarding?

When a communication request is being routed through a network gateway, such as a router or firewall, it is redirected from one address and port number combination to another. This process is known as port forwarding, or port mapping, in computer networking. In actuality, a port forward allows you to connect a computer on your home or business network to the internet, even if the other machines are protected by a firewall or router. By remapping the destination IP address and port number of the communication to an internal host, this approach is most frequently used to make services on a host located on a protected or masqueraded (internal) network available to hosts on the other side of the gateway (external network).

Thus, port forwarding is a means of enabling internet users to establish a connection with you. By using a port forward, you may make a device seem to be directly connected to the internet from outside of your network. For security cameras, torrenting, and the best possible gaming experience, this is required. Because of this, it is frequently utilized in home automation, security cameras, gaming, and the Internet of Things (IoT).

An open port is another name for a forwarded port. You have an open port once a port has been forwarded.

How does Port Forwarding Work?

You must first comprehend the functions of your router in order to comprehend port forwarding. Consider your router to be a hybrid of a mail sorter and a security guard. Your router's NAT (Network Address Translation) firewall transmits incoming connections to the devices that ask for them and, as a result, prevents undesirable incoming data. It accomplishes this automatically, however, port forwarding must be configured if you want your home devices to connect to a distant device.

There are approximately 60,000 ports on your router. Typically, the first 1,000 are devoted to typical, niche functions. You can designate the remainder for any program or device. To accomplish this, open a port on your router and designate it for use with a certain device. Henceforth, a device will immediately establish a direct connection with your network upon receiving a connection request. You will need to know your port number in order to perform this.

The easiest way to explain port forwarding is with the following example:

Let's assume your buddy in a different city needs access to your computer for whatever reason. This implies that users may access your computer as if they were seated in front of it from any location where they have their computer.

Your friend will launch a remote desktop application and use a specified port number to submit a request to your IP address in order to get access to your machine. Here, we'll assume that port 3389 is it. After that, the request makes its way to your router over the internet. Your router has to know where to deliver the request once it reaches it.

Your router will reject the request at this point if it hasn't been instructed to forward any requests from port 3389 since it won't know what to do. However, since port forwarding for 3389 has already been configured, the request will be accepted, establishing a connection that will provide unrestricted data communication.

This procedure resembles the way a switchboard functions when you contact a company that has many extension numbers. Let's take an example where you would want to contact a certain department of a company that utilizes extension 405 by calling. When asked, provide the extension number when you initially contact the company's number to have your call routed to that extension's location. The idea behind port forwarding is similar.

What are the Types of Port Forwarding?

Port forwarding can be classified into several types based on the needs of network users and applications. Here are the main ones.

1. Static Port Forwarding: Static port forwarding uses a defined port number to send internet traffic to a particular device within a local network by manually modifying router settings. Another name for this procedure is port mapping.

   To monitor your home security while you're away, you may utilize static port forwarding in your router settings to establish a direct line of communication between your home surveillance system and any location over the internet.

2. Local Port Forwarding: The most popular type of port forwarding, known as local port forwarding, safely sends data from a client program that is open on your computer. With local port forwarding, you may use an intermediate, generally an SSH tunnel, to route traffic from your local system to another server. By employing local port forwarding, it is possible to get around firewalls that restrict particular pages.

   Let's say you need to safely access your company's internal database while working from a coffee shop. You may establish a secure connection from your laptop to the database as though you were accessing it from inside your company's network by configuring local port forwarding over an SSH tunnel.

3. Remote Port Forwarding: With this kind of port forwarding, a TCP port can be accessed by anybody on the distant server. When remote workers need to access a secure server from home, they most frequently employ remote port forwarding to create external access to an internal web server. In essence, remote port forwarding creates a secure channel, such as an SSH tunnel, that lets outside users access services hosted on your local computer.

   Suppose you are working on an application locally and would like to present it to a customer without putting it on a public server. It is possible to grant external users access to your locally operating program by utilizing remote port forwarding.

4. Dynamic Port Forwarding: Through the use of what are known as firewall pinholes, you may bypass a firewall with this uncommon type of port forwarding. It enables clients to connect securely through a "trusted" server that serves as a middleman for data transmission to other servers.

   With dynamic port forwarding, you may use SOCKS proxy protocols to establish a secure, adaptable tunnel that can route data from several ports to numerous destinations based on real-time requests.

   When you need to safely access your company database or email while traveling and utilizing public Wi-Fi, you may utilize dynamic port forwarding. This kind of port forwarding may route your internet traffic through your home or workplace network, serving as a safe tunnel.

5. UPnP Port Forwarding: It's possible that you have utilized port forwarding in the past without even realizing it or without manually setting the ports. How? Your device made use of Universal Plug and Play (UPnP), which enables your device's apps to open and close router ports as needed. Devices inside a private network may easily communicate and exchange data with other devices or services thanks to UPnP.

6. NAT Port Forwarding: In order to redirect incoming traffic to the correct internal IP address and port, a network address translator (NAT) changes the destination address and port of the traffic. This process is known as NAT port forwarding. For instance, you may use NAT port forwarding on your router to let your pals access your gaming server at home if you wish to play games with them online.

Why is Port Forwarding Important?

Enabling remote access to resources on private networks requires port forwarding. The guests you wish to let in will require a mechanism to do so, as firewalls are designed to keep undesirable visitors out. It is not sufficient to only know the IP address; requests must be sent to the appropriate port. This additional, necessary data provides an additional line of defense against DDoS (direct denial of service) assaults and aids in preventing undesirable visits. The best method for maintaining an IP address is port forwarding. It can strengthen your system and shield customers and servers from intrusions; nonetheless, it is most frequently employed to safeguard public IP addresses. Most significantly, port forwarding gives networks an additional layer of protection. It may "hide" servers and services on a network.

The best way to prevent undesired traffic from entering networks is through port forwarding. It enables networks to use many ports and IP addresses inside, but just one IP address for all communications with the outside world.

When used in conjunction with other identity management applications, port forwarding works exceptionally effectively. Applications that provide multi-factor authentication, single sign-on capabilities, and similar features add an additional degree of protection when permitting access to sensitive locations such as databases and file servers.

Where is Port Forwarding Used For?

Playing video games, controlling access to home cameras, enhancing security, and many other uses are all made possible by port forwarding, which is a very flexible feature. Another advantage of remote computer access is that it allows you to conceal your network or yourself from inquisitive eyes.

The examples that follow are by no means exhaustive, but they should give you a decent notion of some situations in which port forwarding increases efficiency and enhances day-to-day operations for both clients and your business. The following are a few typical applications for port forwarding:

• Backups: Having the ability to access your data, servers, or hard disk clones from any location with an internet connection has its advantages. With port forwarding, those who have the right authorization can access even some of your more difficult-to-reach backups from any location.

• Virtual Desktops: Not every desktop PC has local storage. PCs are better kept in cloud settings in large-scale technological installations like hospitals or colleges. Through port forwarding, customers may utilize any on-site computer to access their own virtual desktops or VDI.

• Security and CCTV: With port forwarding, you may monitor activities from any location. You can effortlessly view your private security feeds from any place, whether it's business or domestic.

• Gaming Servers: Gaming is one of the most common applications for port forwarding. Port forwarding is useful there for running private gaming servers. Companies can use this to conduct tournaments or games for charitable causes, even if the primary use case for this is among friends for recreational private games or maps.

• Web Hosting: Web hosting is the process of storing and serving websites on a server located locally. Port forwarding allows them to be accessed by users via the internet.

• Peer-to-Peer Apps: Port forwarding enhances the efficiency of file-sharing apps such as BitTorrent by enabling direct connections between peers.

Port forwarding entails the configuration of a router to redirect incoming traffic on certain ports to selected devices inside the local network, essentially circumventing the firewall of the router. This configuration is crucial for ensuring that external requests are sent to the appropriate internal device or service.

How does Port Forwarding Work in a Firewall?

Port forwarding is a method used to enable external devices to connect to services on a private network. The process involves rerouting communication requests from one specific address and port number combination to another while the packets go through a network gateway, such as a router or firewall. Below is a detailed breakdown of the process of port forwarding in a firewall:

1. Incoming Request: A request is received from an external device to get access to a service that is being hosted on a private network. This request is specifically targeted at the public IP address of the network's gateway, such as a router or firewall.

2. Port Mapping: The firewall utilizes pre-established rules to associate certain inbound ports with internal IP addresses and ports. For instance, a request that comes in on port 8080 may be redirected to the IP address of an internal server on port 80.

3. Packet Inspection: Packet inspection refers to the process in which the firewall examines the incoming packets to see if they correspond to any of the pre-established port forwarding rules.

4. Redirection: Redirection occurs when the firewall identifies incoming packets that meet a certain rule. In this case, the firewall modifies the destination IP address and port number of the packets to match those of the internal device. The firewall then proceeds to pass the packets to the appropriate destination.

5. Response Handling: Once the internal device sends a response, the firewall accurately associates the response with the initial external IP address and port number, thereby assuring an uninterrupted connection.

This procedure enables external users to get access to internal services without exposing the full internal network, hence improving security while preserving accessibility.

How to tell if Port Forwarding is working?

Check to see that the ports are open and operating correctly after configuring port forwarding. Utilizing an online port checker application such as canyouseeme.org is the most straightforward method to verify port forwarding. This service is offered for free on a number of websites. You may check if the port forwarding is working by following the next steps:

1. Visit the https://canyouseeme.org/ website for the online port checker.

2. In the appropriate field, enter the port number to which you are being routed.

3. Press the "Check port" button. When employing a port forward checker, the following outcomes might appear:

   • Port Open: This is the intended result. It indicates that the port-related service is reachable from the internet and that your port forwarding configuration is accurate.

   • Port Is Closed: Should the test reveal that the port is closed, it may be an indication that your port forwarding configuration is off. You'll need to review and make the required changes to your router or firewall setup.

   • Port Is Filtered or Blocked: The test may occasionally reveal that the port is blocked or filtered. Network limitations of your Internet Service Provider (ISP) may be to blame for this. Another possibility is that traffic on that port is being restricted by your internet service provider (ISP). Alternatively, it's possible that specific kinds of communication are being blocked or filtered by firewall rules or other security measures on your networks.

How to Setup Port Forwarding?

Since each router or brand may have different instructions for port forwarding, the following is a broad outline of what the port forwarding setup procedure can entail:

1. Access your router by logging in. You may accomplish this by typing the IP address of your router, also known as the default gateway, into the address bar of your search engine. Click "Login" after entering your admin username and password.

2. Launch the port forwarding configuration window. The area you want is usually titled "Forwarding," "Port forwarding," "Firewall," or something similar, even though every router has a unique interface. Locate the necessary menu item and choose it.

3. Click "Add rule" or "Add new" to add a personalized port forwarding entry. Include a fresh port forwarding entry.

4. Enter the numbers for the internal and exterior ports after selecting a configuration. While a device within your local network waits for incoming connections on an internal port, an external port is the number that devices on the internet use to access your network. As long as the internal and external devices are aware of which ports to utilize, they often don't need to match one another. Verifying that there are no conflicts with other services sharing the same ports is crucial. Include internal and service port numbers.

5. The device's local IP address, which differs from your router's IP address, should be entered once the ports have been configured. Put the IP address of the device here.

6. Save any changes you make to port forwarding.

With that port enabled, the router may now direct any request made to your device directly without disclosing its private IP address. But how does that request appear? Let's say the IP address of your gadget is 192.168.1.100. A request to your device to connect directly to the camera via port forwarding would be sent to this address: 192.168.1.100:554, if the port you have configured to connect to your home security camera is 554. It functions similarly to using an extension when phoning a number.

note

You may easily configure port forwarding on your OPNsense or define port forwarding rules on pfSense by following the steps given in our tutorials.

Is it a good idea to use port forwarding?

Port forwarding might be advantageous or beneficial, depending on your particular requirements and circumstances. It enables the connection of external devices to a particular device on your local network, facilitating numerous applications including gaming, remote desktop access, and server hosting.

Port forwarding has several advantages, like remote access, enhanced performance and customization. Remote Access allows you the ability to connect to devices and services inside your home network from any location across the globe. By establishing a direct data pathway, it is possible to improve the performance of online games and apps. Moreover, port forwarding enables you to configure your network to suit your own requirements.

On the other hand port forwarding has some drawbacks, such as security risks, complexity, and ISP limitations. It exposes your network to possible external dangers, emphasizing the need to implement robust security procedures. It may provide challenges during setup, particularly for those without technical expertise. Lastly, certain Internet Service Providers (ISPs) may prohibit access to certain ports or impose restrictions on port forwarding.

To summarize, while port forwarding may provide substantial advantages, it is crucial to consider them in relation to the possible security vulnerabilities and intricacy associated with it. Always verify that you have sufficient security protocols implemented to safeguard your network.

Is Port Forwarding Safer than VPN?

Absolutely not, as a VPN (Virtual Private Network) offers data encryption as an extra layer of security. In other words, there are two ways that you can access in-network resources when you're not connected to your network. A VPN is an alternative to port forwarding. One is better than the other, even though both will let you access the resources you require, such as servers, network-attached storage devices, or even your router setup.

Consider the IP address as a large office building, with the ports representing the individual suite numbers corresponding to the many businesses. Therefore, even though you may mail your letter to the office building address, you will need to include the suite number in your address so the post office knows where to deliver it if you want it to go to Company A in Suite 210.

Normally, most of these ports cannot be accessed from the outside internet because of the way your network is configured. This is due to the fact that opening them up to outside traffic has security consequences. Put differently, opening up certain ports to the internet exposes your network to hackers and all the unfavorable consequences that follow.

To be clear, port forwarding has a role and can be effective in some restricted situations and for some particular use cases. But in most situations, a VPN will be a preferable choice.

Although the idea behind a VPN may seem complicated, it's actually extremely easy. Let's return to the large office building and the separate suites from our previous illustration. As an illustration of port forwarding, we marked our mail with our suite number so the postal service would know where to deliver it. Consider a VPN as a heavily guarded, secure office building. Mail cannot be delivered directly to a suite number by the post office; instead, it must be checked in at the front desk. After that, they receive a unique security permit from the front desk, which enables them to enter the remainder of the building and deliver the mail to the designated suite number.

Similar to this, a VPN serves as the "security pass" for all internet-based traffic that enters your network. It makes it possible for a computer that is not connected to the network to function as though it is. It accomplishes this by creating what is referred to as a tunnel. You can avoid having to open up any ports on your network to the public internet by utilizing a VPN. Rather, your computer delivers the traffic through a secure tunnel it has built into your network.

VPNs are better than port forwarding for the following two key reasons:

• They remove a great deal of pointless firewall and router settings.

• They offer more security.

Regarding the first issue, you would have to take the time to set up unique forwarding rules for any traffic that you wished to permit into your network if you were to use port forwarding. Instead, all you have to do to access the necessary internal network resources using a VPN is connected to it; no additional configuration is required.

It is true that the second point is true for several reasons. One benefit of using a VPN is that it eliminates the need for any extra ports to be open to the internet. This reduces the number of possible access points for hackers into your network. Additionally, your computer may send all of its traffic, including internet traffic like Google searches, through the safe VPN tunnel when it is connected to one. Since this tunnel is encrypted, no one from the outside can eavesdrop on it or figure out what it is. Because of this, VPNs are especially helpful for people who often work on public Wi-Fi. With the knowledge that their traffic is safely encrypted behind the VPN tunnel, they may connect to their VPN and safely access protected websites like their online banking.

In conclusion, the recommendation to utilize a VPN over port forwarding should be made virtually always.

What is the difference between Port Forwarding and VPN?

One popular method for getting access to devices behind a firewall is port forwarding. By setting up a firewall rule using port forwarding, traffic is forwarded to a designated device and destination IP port number from any WAN-side IP port number. For instance, a rule permitting access to destination port 80 is necessary in order to see the homepage of a LAN device. Ports 22 and 23 must be accessible in order to permit access to SSH or Telnet, respectively. For the WAN port, an arbitrary IP port number is used.

For the purpose of setting up the rule with the right IP port number and protocol (UDP or TCP), port forwarding requires knowledge about the application. When there are several services and devices, it can soon become difficult to access each one without a distinct port forwarding rule.

By establishing a connection to the IP router or firewall, on the other hand, a VPN grants access to the device and allows one to access any device that is protected by the firewall. It is not necessary to set up individual rules, nor is it necessary to understand the application protocol. Data encryption adds an extra layer of protection that is offered by a VPN. When using the Internet to access things remotely, this is undoubtedly helpful. Certain protocols use plain text to transmit login credentials.

Through Internet port forwarding, a device may be accessed by anybody who knows the firewall's public IP address. VPNs restrict access to authorized users exclusively by requiring VPN client devices to utilize keys and certificates in order to establish connections. This is not to argue against the use of port forwarding. When machine cells or internal networks need to be accessible from an OT infrastructure, this is a valid approach. Use VPNs rather than port forwarding to gain convenient access to remote work sites from your home or workplace.

How Does SASE Eliminate the Need for Traditional Port Forwarding?

Secure Access Service Edge (SASE) combines network security functions with wide-area networking (WAN) capabilities, provided as a cloud-based service, therefore eliminating the need for conventional port forwarding. The following is the method by which SASE does this:

• Centralized Management: SASE offers a unified platform for administering network security policies, reducing the need to manually define port forwarding rules on specific devices or firewalls.

• Zero Trust Network Access (ZTNA): Zero Trust Network Access (ZTNA) is a concept that is integrated into Secure Access Service Edge (SASE). It guarantees that access to apps and services is only allowed based on the user's identity and context, rather than depending on open ports. By reducing the attack surface, the dangers associated with port forwarding are mitigated.

• Cloud-Native Architecture: SASE utilizes a cloud-native architecture to direct traffic via secure gateways. These gateways are responsible for performing essential security checks and enforcing policies, eliminating the need for conventional port forwarding.

• Integrated Security Services: SASE integrates many security services, including firewall-as-a-service (FWaaS), secure web gateways (SWG), and data loss prevention (DLP). These services work together to safely manage traffic without requiring manual port setups.

• Dynamic Scalability: SASE's cloud-based architecture enables dynamic scalability, meaning it can dynamically react to changing traffic needs and security requirements without relying on static port forwarding rules.

SASE streamlines network administration and improves security by consolidating these features inside a unified framework, making conventional port forwarding unnecessary.