Networks are now involved in nearly every event that occurs in our interconnected world. Whether you’re playing online games, hosting a website, or accessing a home security camera, network management should interface those activities. One technique that helps enable any of those activities is port forwarding.
What is Port Forwarding?
Port forwarding (also known as port mapping) is a networking process to take incoming traffic from the internet and properly direct it to a certain device or service that is contained in a local network. Port forwarding allows external devices to talk to devices that are behind a router (or firewall) by “opening” ports and forwarding to the correct internal IP address.
Why Is Port Forwarding Important?
Most home and business networks utilize a router that implements Network Address Translation (NAT). NAT allows for internal IP addresses to stay hidden for security reasons. If a device is pulling an internal IP, it cannot be contacted directly from the internet. Port forwarding allows certain services to be available externally and provides access to those services internal to your network.
Why and when to use port forwarding?
You might need to set up port forwarding in situations like:
- Hosting your own game server so friends can connect online
- Checking your home security camera while you’re away
- Running a website or FTP server from your computer
- Connecting to your PC or laptop using remote desktop apps
ie, port forwarding helps you reach devices or services inside your network from anywhere outside it safely and easily.
How Port Forwarding works?
Here’s a rundown of how port forwarding works.
Port forwarding works through the TCP protocol, which is one of the most common ways computers exchange data over the internet. TCP forwarding acts like a secure bridge that directs incoming traffic from the outside world to the correct device or service inside your local network. TCP forwarding is also sometimes referred to as a specific implementation or use of port forwarding.
Here are the steps with TCP forwarding:
- Identify the Service and Port : Determine which port your service uses — for example, HTTP runs on port 80.
- Configure Your Router : Log in to your router’s admin panel and create a port forwarding rule for that service.
- Link Internal and External Addresses : Connect the external port (used by devices outside your network) to the internal IP address and port of the device hosting the service.
- Test the Connection : Check that the port is open and accessible from the internet to confirm everything is working correctly.
How to configure Port Forwarding?
- Log into the router’s administrative panel (normally through a browser).
- Look for a section named Port Forwarding, Virtual Servers or Applications & Gaming.
- Enter the service specification:
Service Name : Example: Web Server
External Port : Example: 8080
Internal IP : Example: 192.168.1.100
Internal Port : Example 80
Protocol : TCP, UDP, or both - Save settings, and restart the router if prompted.
- Verify that the port is open with an online port checker, such as CanYouSeeMe or PingTools.
Is TCP Forwarding Different than Port Forwarding?
Although the terms are related, they aren’t exactly the same.
Port forwarding is the general idea of sending network traffic from one IP address and port to another.
TCP forwarding is a type of port forwarding that only works with TCP traffic (the kind most websites and apps use).
All TCP forwarding is port forwarding, but not all port forwarding is TCP forwarding (it could be UDP).
Types of Port Forwarding
Beyond basic port forwarding on a router, there are several powerful forwarding methods that are typically handled through software on servers or dedicated devices.
- SSH Tunneling (Port Forwarding):
Secure Shell (SSH) is a protocol used to access a computer, remotely, and execute commands securely. However, it is possible to create an encrypted “tunnel” and forward traffic, a feature that is particularly useful for security and overcoming banal network restrictions.
Local Port Forwarding: This method will forward a port from your local machine to a remote server. For instance, you could forward your local port 8888 to a remote database port (3306) allowing you to refer to the database as if it were being accessed from your own machine.
Remote Port Forwarding: This does the opposite; taking a port on your local machine and making it present from the remote SSH server. This is often done to surface a local development server to the internet (for a short time).
Dynamic Port Forwarding (SOCKS Proxy): Allows your SSH/executable client to act as an encrypting SOCKS proxy server. Therefore, all of your application traffic (browser, even email) can be routed through the encrypted tunnel to the remote the SSH server and you will use the network from the remote server for browsing.
2. Reverse Proxy :
A reverse proxy server (Nginx or Apache, etc.) is used to forward requests to web servers over the internet. Essentially, the reverse proxy is in front of web servers. When it receives requests from clients, it forwards them to the web server after determining which backend server to send them to. A little different than port forwarding, a reverse proxy is an application layer (Layer 7) that can make intelligent decisions from information contained in the request (i.e., the URL).
Here are the benefits of reverse proxy:
Load Balancing: Traffic can be distributed across numerous backend servers.
SSL Termination: Offloads the process of HTTPS encryption/decryption from backend servers.
Security: Reverse proxies can hide the details of backend servers.
3. VPN (Virtual Private Network) :
VPNs are the zenith of how far you can take “forwarding.” Instead of just forwarding one port, the VPN includes ALL your network connection (i.e., as if your whole network connection is protected). This includes taking all your device’s traffic and encrypting it to route it through a remote VPN server. It may even look as if you are on the remote VPN’s physical local site. While there are security, privacy, and network resources (as if you are in person) benefits with a VPN, you should consider some security weaknesses as well.
Security Considerations :
While port forwarding is a powerful tool, ports can present some security weaknesses.
Unauthorized Access: An open port can be accessed and exploited if the respective service is not adequately secured.
Malware and Denial of Service (DoS) Attacks: An exposed service may attract malicious activity.
How to mitigate the risks of port forwarding?
- Ensure strong unique passwords for services.
- Make sure services had up to date software and firmware.
- Only open essential ports.
- Instead of openings ports permanently you could consider using a VPN or SSH tunnel for more secure remote access
Conclusion
Port forwarding is a necessary technique for giving access to internal network services to the outside world. When properly set up it can improve functionality and ease of use, but it must be actively managed to help maintain network security. By understanding the finer points of TCP forwarding, how it differs by Protocol, as well as the advanced techniques such as SSH tunneling and reverse proxies, you are better able to make an informed decision on how to make use of your new knowledge, improving the versatility, efficiency, and security of your network. Whether you want to host a game server, connect to a home security outdoor system, or develop a comprehensive web application stack, these forwarding mechanisms are a basic piece of the connected world.