Skip to main content

LambdaTest Underpass Application For Secure Tunnel

With LambdaTest Underpass, you can perform cross browser testing of locally hosted web applications on 3000+ browsers for both mobile & desktop, without executing any command from your terminal. LambdaTest Underpass is a desktop application to help you establish an SSH(Secure Shell) tunnel between your operating system & our cloud servers, all through GUI.

Downloading & Installing The Underpass Tunnel Application

Important Links
Download Underpass For Windows
Download Underpass For macOS
Download Underpass For Linux

You can also download the Underpass tunnel application from the LambdaTest web-application. Login to your LambdaTest account, and hit the button to configure tunnel. After that, switch to the tab “Download App” and click the button which says “Download Tunnel App”. This will download the binary file using which you can perform browser compatibility testing over your locally hosted web-applications or websites.

LambdaTest Underpass

After downloading the Tunnel App, also known as the Underpass, you need to run it. You may get a prompt from your operating system asking you to allow Underpass through the firewall on your system.

LambdaTest Underpass

Note: If you are using a Linux operating system, you need to give app executable permission using the command:

chmod +x UnderPass.AppImage

Launching The Secure Tunnel Through Underpass

For Linux User

Make sure you’ve given the permissions to the Underpass executable file through the command highlighted in the above note. If you have, you can run the application by either double clicking it or by running the below command in terminal:


For Windows User

You would have to specify your LambdaTest Username & LambdaTest Access Key to establish an secure tunnel connection.

LambdaTest Underpass

Note: By default, a tunnel name would be automatically assigned. In case you don’t like it, you can go ahead and change it by hitting the refresh icon.

Finding Your LambdaTest Username & Access Key

Login to your LambdaTest account. Click on the user icon over the top-right and visit the Profile.

LambdaTest Underpass

In your profile, you will find your LambdaTest Username and Access key.

LambdaTest Underpass

Now, you need to copy your LambdaTest Username and Access Key to place in the Underpass tunnel application. Hit the Launch button.

LambdaTest Underpass

Note: You may get another promt from your firewall defender to allow LT, which is a binary file for Lambda Tunnel. Earlier, you used to trigger the LT file through your command line or terminal. Now, as you allow LT(Lambda Tunnel) the permissions, the Underpass will take care of the rest of the execution.

LambdaTest Underpass

Next, you just have to wait for a couple seconds and ta-da! You have successfully established an Secure Shell connection by running the Underpass application. You will find the status as Running.

LambdaTest Underpass

By clicking over the View Logs button, you can find messages populated from through command line.

LambdaTest Underpass

Note: If you don’t specify any advanced configurations while launching the tunnel, you may receive few warnings stating the environment & configuration files aren’t found. Don’t worry though, in such cases you will be automatically routed through default configurations.

Now, if you go back to LambdaTest web-application, you will find an active tunnel connection being reflected with the same name as your Underpass tunnel application.

LambdaTest Underpass

What About The Advanced Configurations?

You can also specify advanced configurations such as proxy details, environment label, info API port, local server port and more before you launch the Underpass tunnel application.

LambdaTest Underpass

As you click on Show Advanced Configurations, you get the below screen.

LambdaTest Underpass

Local Testing By MITM(Man-In-The-Middle)

The MITM(Man-in-the-middle) toggle enables you to test websites using self-signed certificates on your local system or internal network. It happens very often that you may try to test a website on localhost which may not have valid SSL certificates before the website is made live. In such cases, you may recieve the below error.

LambdaTest Underpass

You can test such websites by leveraging the MITM toggle under advanced configurations of the Underpass tunnel application. Here is a screenshot of the same website that was throwing an error earlier but can now be tested by enabling the MITM toggle.

LambdaTest Underpass

Accessing A Local Directory

With Underpass application, you can easily access a local folder or directory in your computer. All you need to do is paste the address of folder in the field “LOCAL DIRECTORY” under the advanced configurations.

LambdaTest Underpass

Now, when you launch the tunnel and run a Real time test over LambdaTest, you will find the files located under the local folder whose path was specified by you under the advanced configurations.

Note: You need to specify as the testing URL in the real time testing.

LambdaTest Underpass

Monitoring Tunnel Logs For Troubleshooting

Through Underpass tunnel application, we’ve tried our best to provide you a bug-free experience. However, in any rare scenario, if you come across any issues around LambdaTest Underpass, you can share the tunnel logs with our 24/7 support, and we will help you out at once.

To view the tunnel logs instantly, click on the Show Advanced.

LambdaTest Underpass

Then click on the tunnel logs address under Log File Directory.

LambdaTest Underpass

You can view the tunnel logs using the below commands for your operating systems:

  • macOS: ~/Library/Application Support/Underpass/logs
  • Windows: C:\Users\%USERNAME%\AppData\Local\Underpass\logs
  • Linux: ~/.config/Underpass/logs

That was all for LambdaTest Underpass tunnel application, in case you have any questions, feel free to share them with us through our 24/7 chat support or drop us an email to Happy testing! 🙂