How to Reverse Tunnel to a Different Local IP

How to Reverse Tunnel to a Different Local IP

Have you ever needed to access a device or service on your home network while you were away? Maybe you wanted to connect to your home computer or access files on your NAS (Network Attached Storage) device. One way to achieve this is by using reverse tunneling. In this article, we will explain what reverse tunneling is and how you can set it up to connect to a different local IP address.

Understanding Reverse Tunneling

Reverse tunneling allows you to establish a connection from a remote device to a device on your local network. It essentially creates a secure tunnel through the internet, allowing you to access services on your local network as if you were physically present at home.

Typically, devices on your home network are assigned private IP addresses, such as 192.168.x.x or 10.x.x.x. These IP addresses are not accessible from the internet. However, by setting up a reverse tunnel, you can access these devices using a public IP address or a domain name.

Setting Up Reverse Tunneling

To set up reverse tunneling, you will need a device on your local network that can act as a server. This server will establish the connection between your remote device and the device you want to access on your local network. Here's how you can do it:

1. Choose a Server: Select a device on your local network that will act as the server. This device should be always on and connected to the internet. It could be your home computer or a dedicated server.
2. Install SSH Server: Ensure that the server device has an SSH server installed. SSH (Secure Shell) is a secure protocol used for remote access. You can install an SSH server like OpenSSH on most operating systems.
3. Configure Port Forwarding: Log in to your router's administration panel and set up port forwarding for SSH. Forward incoming traffic on port 22 (default SSH port) to the local IP address of your server device.
4. Obtain Public IP or Domain Name: Determine the public IP address of your home network or set up a dynamic DNS service to associate a domain name with your IP address. This step is crucial for connecting to your server device from the internet.
5. Connect to Server: On your remote device (e.g., your laptop or smartphone), open an SSH client. If you are using Windows, you can use a client like PuTTY. Connect to the public IP address or domain name of your home network using the SSH client.
6. Set Up Reverse Tunnel: Once connected to the server, you can set up the reverse tunnel. Use the following command:

ssh -R <remote-port>:localhost:<local-port> user@public-ip-address

Replace <remote-port> with the port number you want to use on the server side (e.g., 8888) and <local-port> with the port number of the device you want to access on your local network (e.g., 80 for a web server).

For example, if you want to access a web server running on port 80 of a device with the local IP address 192.168.1.100, and you want to use port 8888 on the server side, the command will be:

ssh -R 8888:localhost:80 user@public-ip-address

Once the reverse tunnel is established, any traffic sent to the server's port will be forwarded to the specified local IP and port on your home network.

Accessing the Device on Your Local Network

Now that the reverse tunnel is set up, you can access the device on your local network from your remote device. Here's how:

1. Open a Web Browser: On your remote device, open a web browser or any other application that can connect to the internet.
2. Connect to Local IP: In the address bar of your web browser, enter localhost:<remote-port>. Replace <remote-port> with the port number you used in the SSH command.
3. Access the Device: You should now be able to access the device on your local network as if you were connected directly to it. For example, if you set up a reverse tunnel to a web server, you can now browse the website hosted on that server.

Remember, the reverse tunnel will stay active as long as the SSH connection remains open. If you close the SSH client or lose internet connectivity, you will need to establish the reverse tunnel again.

Conclusion

Reverse tunneling is a powerful technique that allows you to access devices and services on your local network from anywhere in the world. By following the steps outlined in this article, you can easily set up a reverse tunnel to a different local IP address. Just make sure to choose a reliable server device and keep the SSH connection active for seamless access to your home network.