How to tunnel localhost to the public Internet
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Introduction
In this article, I’m going to show you how you can tunnel your localhost environment to a public Internet address that can be accessed by other services you are using for testing.
Why tunnel localhost to a public Internet address?
If you are optimizing the front-end of a given web application and want to see how effective your changes are, you can use a tool like GT Metrix or Pingdom Website Testing.
The problem is that those tools can access only a public Internet address, not your localhost environment. And, while you can deploy your temporary changes to a QA environment that’s publicly accessible, there’s a much simpler way to achieve this goal.
Or, while developing RevoGain, the most awesome Revolut trading grain calculator, I had to test the FastSpring payment integration. The payment callbacks need a public Internet address that FastSpring calls after making a purchase. To test the integration, you’d need to expose your localhost environment to a public Internet address so that FastSpring can call your own environment.
And, the solution to this problem is to open a networking tunnel between localhost and some public Internet address all those services can access.
Networking tunnel
In networking, a tunnel allows you to transport packets from a private network to a public network. For instance, tunneling is used with VPN (virtual private networks) to secure network connections.
The Linux ssh port forwarding is also using another example of a networking tunnel, which allows you to transport packets securely from your localhost environment to a public network.
Ngrok
While there are many ways to create a networking tunnel, my favorite tool is Ngrok. After I downloaded the tool, I created a tunnel.bat script that’s available on the Windows PATH:
@echo off call ngrok http %*
To open an HTTP or HTTPS tunnel, all I have to do is run the following command:
> tunnel 8080
ngrok by @inconshreveable
Session Status online
Version 2.3.40
Region United States (us)
Web Interface http://127.0.0.1:4040
Forwarding http://956e-188-24-86-235.ngrok.io 🡒 http://localhost:8080
Forwarding https://956e-188-24-86-235.ngrok.io 🡒 http://localhost:808
Connections ttl opn rt1 rt5 p50 p90
0 0 0.00 0.00 0.00 0.00
That’s it!
Now, localhost:8080 is available at the 246d-188-24-86-235.ngrok.io address. And the 246d-188-24-86-235.ngrok.io uses an HTTPS tunnel to my localhost environment.
Testing time
To test how well the front-end performs, I now can use GT Metrix to analyze the Spring Boot server running on my localhost environment:
When going to the NGrok command line window, I can see various metrics about the networking connections established via the tunnel:
Connections ttl opn rt1 rt5 p50 p90
24 0 0.00 0.01 0.24 32.28
Awesome, right?
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Conclusion
Exposing your localhost environment to a public Internet address is a very handy feature when testing a web application.
NGrok is a very simple tool that allows you to create a networking tunnel between your private web server and a public Internet address.
