What is Port Forwarding?

what is port forwarding and use cases

Port forwarding is a networking technique that redirects incoming network traffic from one network port on a router or firewall to another network port on a different device within the local network. It is commonly used to enable remote access to services or devices located behind a router or firewall and to facilitate communication between devices on different networks. Here are some common use cases of port forwarding: 1. **Remote Access to Local Services**: Port forwarding allows users to access services, such as web servers, FTP servers, or gaming servers, hosted on devices within their local network from outside the network. For example, by forwarding port 80 to a local web server's IP address, users can access the web server's content from the internet using the router's public IP address. 2. **Remote Desktop Access**: Port forwarding can be used to enable remote desktop access to computers or servers within a local network. By forwarding the appropriate ports (e.g., port 3389 for Remote Desktop Protocol, or RDP), users can remotely connect to their computers or servers from outside the network using remote desktop software. 3. **File Sharing and FTP Services**: Port forwarding is commonly used to enable file sharing and FTP (File Transfer Protocol) services hosted on devices within a local network. By forwarding the FTP port (typically port 21) to an FTP server's IP address, users can upload, download, and share files securely over the internet. 4. **Gaming and Peer-to-Peer Services**: Many online games and peer-to-peer (P2P) applications require specific ports to be open for incoming connections. Port forwarding allows gamers and P2P users to host multiplayer game servers or participate in P2P networks by forwarding the necessary ports on their routers or firewalls. 5. **IP Camera and IoT Device Access**: Port forwarding enables remote access to IP cameras, home automation devices, and other IoT (Internet of Things) devices within a local network. By forwarding ports associated with these devices (e.g., ports 80 or 443 for IP cameras), users can monitor and control their devices remotely over the internet. 6. **VoIP (Voice over IP) Services**: Port forwarding may be necessary to enable VoIP services, such as SIP (Session Initiation Protocol) or RTP (Real-time Transport Protocol), to operate properly behind a router or firewall. By forwarding the required ports, users can ensure reliable communication for voice and video calls over the internet. Overall, port forwarding is a versatile networking technique that allows users to access and interact with services and devices within their local network from outside the network, enabling remote access, communication, and collaboration across different networks and locations.

Difference between port forwarding and port address translation

Port forwarding and port address translation (PAT), also known as NAT overload, are both techniques used in networking to facilitate communication between devices on different networks, but they serve different purposes and operate at different layers of the network stack. 1. **Port Forwarding**: - Port forwarding, also known as port mapping, is a technique used to redirect incoming network traffic from one network port on a router or firewall to another network port on a different device within the local network. - Port forwarding is typically used to enable remote access to services or devices hosted within a private network from outside the network. It allows external users to access specific services or servers hosted on devices within the local network. - Port forwarding requires explicit configuration on the router or firewall, where specific inbound ports are mapped to corresponding ports on internal devices based on predefined rules. - Port forwarding operates at the transport layer (Layer 4) of the OSI model, primarily dealing with TCP/UDP ports. 2. **Port Address Translation (PAT)**: - Port Address Translation, also known as NAT overload, is a type of network address translation (NAT) technique used to translate multiple private IP addresses to a single public IP address, with each private IP address mapped to a unique port number. - PAT allows multiple devices within a private network to share a single public IP address for outbound communication while maintaining the uniqueness of each connection by using different port numbers. - PAT is commonly used in scenarios where there are more internal devices than available public IP addresses, such as in small office/home office (SOHO) environments or enterprise networks. - PAT operates at the network layer (Layer 3) of the OSI model, translating IP addresses and port numbers in the packet headers as traffic passes through the NAT device. In summary, port forwarding is used to redirect specific inbound ports from a router or firewall to internal devices, enabling remote access to services hosted within a private network. On the other hand, PAT is used to translate multiple private IP addresses to a single public IP address, with each connection uniquely identified by a combination of the public IP address and port number. While port forwarding deals with individual ports and specific services, PAT deals with IP address and port number translation for outbound traffic from multiple devices.

Port forwarding is the process that your router or firewall uses to sort the right kind of network data to the right port. Computers and routers use ports as a way to organize network data. Different types of data, such as websites, file downloads, and online games, are each assigned a port number. By using port forwarding, the router or firewall sends the correct data to the correct place.

A firewall protects your computer by blocking unauthorized information. If a firewall blocked all the incoming and outgoing data, the computer would be unable to access the Internet. When you want some data to go through your firewall, and you want it sent to a specific location, you can set up port forwarding. Port forwarding gives the firewall instructions about which types of data are allowed and how they should be directed.

Information on the Internet is associated with a port. Web pages, for example, are typically assigned port 80. File transfer protocol (FTP), often used for downloading and uploading files, typically uses port 21. Online games may use a number of different port numbers, but often choose numbers in the thousands.

If you have multiple computers on your network, chances are that they do not all need all the data that comes into the network. Port forwarding allows you to send the relevant data to the computer that will use it. If you have a web server hosting your website, and a second computer hosting an online game, port forwarding will make sure that each computer receives the data it needs, without being bogged down with data intended for the other computer.

In this situation, you would use port forwarding to instruct your router as to which computer is the destination for which data. The port forwarding instructions would send all incoming requests for web pages to the web server. This data would come into the router at port 80, and the port forwarding instructions route that data to the web server.

The online game server might be set to use port 5500. Any data that comes to the network at port 5500 should be from people trying to play the online game using your computer as a host. The port forwarding information in the router will direct all data coming in using port 5500 to go to the online game hosting computer.

Using port forwarding also serves as another way to protect your computers. People outside your network will only have access to the router or firewall. The router or firewall with port forwarding controls which types of data reach your computers. Any data that does not come to the router with the correct port will not be passed through to the computers inside the network.

Not only does port forwarding keep incoming data flowing to the right computer, but it also helps to protect your network by limiting and controlling outside access. If your network includes a web server, FTP server, or game server, or runs other services that require outside access, port forwarding will help keep your network safe and running smoothly.