Add the URL Content Redirection ADMX Template to a GPO

The URL Content Redirection ADMX template file, called urlRedirection.admx, contains settings that enable you to control whether a URL link is opened on the client (agent-to-client redirection) or in a remote desktop or published application (client-to-agent redirection).

To apply the URL Content Redirection group policy settings to your remote desktops and published applications, add the ADMX template file to GPOs on your Active Directory server. For rules regarding URL links clicked in a remote desktop or published application, the GPOs must be linked to the OU that contains your virtual desktops and RDS hosts.

You can also apply the group policy settings to a GPO that is linked to the OU that contains your Windows client computers, but the preferred method for configuring client-to-agent redirection is to use the horizonutil command-line utility. Because macOS does not support GPOs, you must use vmdutil if you have Mac clients.

Prerequisites

• Verify that the URL Content Redirection feature is included when you install Horizon Agent. See Installing Horizon Agent with the URL Content Redirection Feature Enabled.
• Verify that Active Directory GPOs are created for the URL Content Redirection group policy settings.
• Verify that the MMC and the Group Policy Management Editor snap-in are available on your Active Directory server.

Procedure

1. Download the Horizon GPO Bundle .zip file from Omnissa Customer Connect.

   Under Desktop & End-User Computing, select the Horizon download, which includes the GPO Bundle.

2. Unzip the file and copy the URL Content Redirection ADMX file to your Active Directory server.

   1. Copy the urlRedirection.admx file to the C:\Windows\PolicyDefinitions folder.

   2. Copy the urlRedirection.adml language resource file to the appropriate subfolder in C:\Windows\PolicyDefinitions.

      For example, for the EN locale, copy the urlRedirection.adml file to the C:\Windows\PolicyDefinitions\en-US folder.

3. On your Active Directory server, open the Group Policy Management Editor.

   The URL Content Redirection group policy settings are installed in Computer Configuration > Policies > Administrative Templates > Horizon URL Redirection.

Configure URL Content Redirection for Custom Protocols

Once you have added the URL Content Redirection ADMX template to the GPO, follow these steps to configure other protocols, such as mailto:

Example: Configuring the mailto Protocol

Solution 1: Using Group Policy (GPO)

1. Modify the urlRedirection.admx file.

   • Open the urlRedirection.admx file located at C:\Windows\PolicyDefinitions.
   • Replace the following content:
     <policy name="UrlRedirectionProtocol_" class="Machine" displayName="$(string.unknown_15)" explainText="$(string.HelpString)" presentation="$(presentation.UrlRedirectionProtocol_)" key="SOFTWARE\Omnissa\Horizon\URLRedirection\...">
     
     With the updated content for the mailto protocol:
     <policy name="UrlRedirectionProtocol_mailto" class="Machine" displayName="$(string.unknown_15)" explainText="$(string.HelpString)" presentation="$(presentation.UrlRedirectionProtocol_mailto)" key="SOFTWARE\Omnissa\Horizon\URLRedirection\mailto">

2. Modify the ADML file.

   • Open the urlRedirection.adml file located at C:\Windows\PolicyDefinitions\en-US
   • Replace the following content:
     

<string id="unknown_15">Url Redirection Protocol '...'</string>
<presentation id="UrlRedirectionProtocol_">
With:
<string id="unknown_15">Url Redirection Protocol 'mailto'</string>
<presentation id="UrlRedirectionProtocol_mailto">

3. Configure the GPO: Open the Group Policy Editor (GPO) and configure the redirection rule for mailto just like the http/https protocols.
   
4. Whitelist the Default Application:

• Add the default app process for the mailto protocol in the urlwhitelist configuration.
• For example, if the default app for the mailto protocol is Microsoft Outlook (as in many machines), no additional settings may be required.
• If the default app is not installed, add horizon-url-protocol-launch-helper.exe in the urlwhitelist configuration.
• If using a different app, modify the registry at Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\vmwicpdr to include the new process in the Whitelist.

5. Restart the Machine: If non-default applications are used for redirection, restart the machine for the changes to take effect.

Solution 2: Direct Registry Configuration

If you need to configure multiple protocols, editing the registry directly can simplify the process:

1. Skip steps 1 to 3 from Solution 1.

2. Directly modify the registry at the following path:

   • Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Omnissa\Horizon\URLRedirection
   • Add a new key for the desired protocol (e.g., mailto) and configure the filter rules under that key.
   • You can add other protocols here as needed.
   
   

What to do next

Configure the group policy settings. See URL Content Redirection Group Policy Settings.