Trust Fiddler's Certificate Authority

This article provides additional information about the options for installing the Fiddler Everywhere certificate authority (CA) in your operating system. The proper certificate installation is a crucial step when using Fiddler Everywhere to capture system HTTPS traffic. Note that the certificate authority installation is not mandatory if you choose to use the independent browser capturing or terminal capturing modes.

Install the Fiddler's Certificate Authority (Recommended Automated Approach)

The recommended approach for installing and trusting the Fiddler CA is through the in-app system capturing mode wizards. Follow the articles below for detailed instructions on how to use the built-in wizards to install the Fiddler CA.

Open the Home pane.
Open the System Proxy tutorial and follow the instructions. During the configuration steps, you will be prompted to install and trust the Fiddler CA with your operating system certificate manager.

Once Fiddler CA installs successfully, you can capture and analyze HTTPS traffic. The CA install once and remains valid until it is explicitly uninstalled. The CA name as listed within the operating system certificate manager is Fiddler Root Certificate Authority.

Install the Fiddler's Certificate Authority (Manual Approach)

Fiddler Everywhere provides the option to manually go through the certificate authority installation and enable the HTTPS system traffic capture. In most cases, to capture the operating system HTTPS traffic, you can use the recommended automated installation of the Fiddler CA through our wizards.

Use the manual approach only if the automated approach fails or you want to control and track the different steps of the CA installation.

As Fiddler Everywhere is a cross-platform web-debugging proxy available for Windows, macOS, and Linux, you must follow the respective approach for installing the tool.

Windows

Start Fiddler Everywhere and go to Settings > HTTPS.
Click the Trust Fiddler CA button. Confirm your choice and add the certificate in the popup that appears.

The Trust Fiddler CA option automatically exports and installs the Fiddler CA in the Windows user store. If you want to install the Fiddler CA in the Windows machine store (to be globally used from different users) then use the Trust Fiddler CA in the Machine Store from the Advanced Options.
Enable capturing the HTTPS traffic by selecting the Capture HTTPS traffic checkbox. Click Save.
Back on the foremost Fiddler Everywhere screen, toggle ON the System Proxy to start capturing HTTP and HTTPS system traffic.

macOS

Start Fiddler Everywhere and go to Settings > HTTPS.
Click the Trust Fiddler CA button.
In the window that appears, enter your machine's administrative credentials.
Enable capturing the HTTPS traffic by selecting the Capture HTTPS traffic checkbox. Click Save.
Back on the foremost Fiddler Everywhere screen, enable the Live Traffic to toggle to start capturing HTTP and HTTPS system traffic.

Linux

Start Fiddler Everywhere and go to Settings > HTTPS. Expand the Advanced Settings sub-menu and use the Export Fiddler CA(DER/Binary format) from the drop-down menu. The certificate is exported to ~/Desktop as a file with the name Fiddler_Root_Certificate_Authority.crt.
To import and trust the exported certificate, perform the following steps.

(For localized Linux distributions only) Some Linux distributions, such as Ubuntu, use localized paths—for example, the name of the Desktop folder translates into the locale language. To resolve this issue, create a folder named Desktop in your root through mkdir ~/Desktop. Then, export the certificate to the newly-created directory. Once the certificate is installed, you can safely remove that directory.
1. Create a directory and copy the exported certificate by running the following commands.
```
$ sudo mkdir /usr/share/ca-certificates/extra
$ sudo cp ~/Desktop/Fiddler_Root_Certificate_Authority.crt /usr/share/ca-certificates/extra

// Starts the tool and upgrades the certificates.
$ sudo dpkg-reconfigure ca-certificates
```
  In case your Linux distribution does not use the dpkg library, then refer to your OS documentation for alternative ways to handle the CA installation or use our dedicated Fedora, CentOS, RedHat and XFCE instructions.
2. From the prompt, select Yes to install new certificates.
3. Choose the Fiddler_Root_Certificate_Authority.crt file (while using the Space bar) and click OK.
4. The certificates are now updated.
Enable capturing the HTTPS traffic by selecting the Capture HTTPS traffic checkbox and clicking Save.
Back in the foremost Fiddler Everywhere screen, toggle ON the System Proxy to capture HTTP and HTTPS system traffic.

Fiddler Everywhere enables you to control the certificate installation and HTTPS system capture. Use the HTTPS menu for more advanced features and options related to the root trust certificate and the HTTPS system capture.

Fiddler Everywhere provides the independent browser capturing mode, which enables you to skip the system capturing configuration. The predefined browser-capturing option comes in handy when you generate captured traffic only from a browser, lack administrative rights to install certificates and modify the system proxy, or when third-party VPNs and security tools collide with the Fiddler Everywhere proxy.

Exporting the Fiddler CA

The automatic installation of the trust certificate can fail due to security restrictions, compatibility issues, limited read/write rights, corporate policies, etc. In that case, the Fiddler Everywhere application presents an error message that notifies the user that the certificate installation has failed. You can export the Fiddler certificate and install it to solve similar issues manually.

Start Fiddler Everywhere and go to Settings > HTTPS > Advanced Settings.
Choose the proper certificate format (DER/Binary, PEM/ASCII, and PKCS 12) and click the Export Fiddler CA button. The export option will export the certificate to a root folder called Desktop, so ensure that such a folder exists in your file system.
Add the exported certificate to the desired certificate manager (for example, on Linux, macOS, custom application, etc.).
Enable capturing the HTTPS traffic by selecting the Capture HTTPS traffic checkbox. Click Save.
Back in the Traffic pane, enable the System Proxy to start capturing HTTP and HTTPS system traffic.

Install Fiddler's Certificate Authority in Third-Party Certificate Stores

Fiddler Everywhere can export the CA file in different formats, enabling you to install the Fiddler CA in third-party certificate stores.