Introduction

Port forwarding is a technique that allows external devices to access a device that is behind a firewall, NAT, or private network. It is commonly used to make a local server accessible from the internet.

ngrok is a tool that creates a secure tunnel to your local server. It is free to use, but you can also buy a paid plan to get more features. ngrok is available for Windows, macOS, Linux, Docker, FreeBSD, etc.

Steps

1. Download ngrok

Download ngrok from the official website.

You can also use wget to download ngrok directly to your server. This is useful if you want to use ngrok on a server that does not have a GUI.

Note: Install wget if it is not installed on your server. For Debian/Ubuntu, you can install it with sudo apt install wget. For CentOS/RHEL, you can install it with sudo yum install wget.

Install wget on CentOS

Install wget on CentOS

Download ngrok with this command:

wget https://bin.equinox.io/c/bNyj1mQVY4c/ngrok-v3-stable-linux-amd64.tgz --no-check-certificate

--no-check-certificate is used to bypass the SSL certificate check. This is useful if you are using a self-signed certificate.

ngrok download

ngrok download

2. Extract ngrok

Extract it to a directory of your choice. I will use /usr/local/bin in this example.

tar -xzf ngrok-v3-stable-linux-amd64.tgz -C /usr/local/bin

ngrok extract

That command will extract the ngrok binary to /usr/local/bin. You can check if it is installed correctly by running ngrok --version

ngrok version

3. Create an account

Create an account on ngrok and get your auth token from the dashboard .

ngrok dashboard

4. Connect your account

Connect your account by running ngrok authtoken <your_auth_token>. Replace <your_auth_token> with your auth token.

or

ngrok config add-authtoken <your_auth_token>

ngrok connect

5. Start ngrok

In this example, I want to make my local SSH server accessible from the internet. So, I will use port 22 for this example.

Run ngrok tcp 22 to start ngrok.

ngrok start

6. Connect to your server

Connect to your server with the ngrok URL.

Domain: 0.tcp.ap.ngrok.io
Port: 11507

So the full command will be ssh username@0.tcp.ap.ngrok.io -p 11507

Install wget on CentOS

Remote SSH the CentOS 7 using Ubuntu 22.04.2 LTS (WSL) with ngrok

Note: The ngrok URL will change every time you start ngrok. So, you need to update the URL every time you start ngrok.

Conclusion

That’s it! Now you can make your local server accessible from the internet with ngrok. You can also use ngrok to make your local website accessible from the internet. Just use the right tunnel type for your server.

For example, if you want to make your local website accessible from the internet, you can use ngrok http 80 to start ngrok. Then you can access your website with the ngrok URL. You can also use ngrok to make your local SSH server accessible from the internet. Just use ngrok tcp 22 to start ngrok. Then you can connect to your server with the ngrok URL.

Further reading: ngrok Tunnels

References