Host to client redirection

Content redirection allows you to control whether users access information with applications published on servers or with applications running locally on user devices.

Host to client redirection is one kind of content redirection. It is supported only on Server OS VDAs (not Desktop OS VDAs).

• When host to client redirection is enabled, URLs are intercepted at the server VDA and sent to the user device. The web browser or multimedia player on the user device opens these URLs.
• If you enable host to client redirection and the user device fails to connect to a URL, the URL is redirected back to the server VDA.
• When host to client redirection is disabled, users open the URLs with web browsers or multimedia players located on the server VDA.
• When host to client redirection is enabled, users cannot disable it.

Host to client redirection was previously known as server to client redirection.

You might consider using host to client redirection in specific but uncommon cases, for performance, compatibility, or compliance. Normally, other forms of content redirection are better.

Performance

You can use host to client redirection for performance, so that whenever an application is installed on the user device, it is used in preference to an application on the VDA.

Keep in mind that host to client redirection will improve performance only under specific conditions, because the VDA already optimizes Adobe Flash and other types of multimedia content.  First, consider using the other approaches (policy settings) noted in the tables below, rather than host to client redirection; they offer more flexibility and usually give a better user experience, particularly for less-powerful user devices.

Compatibility

You can use host to client redirection for compatibility in the following use cases:

• You use content types other than HTML or multimedia (for example, a custom URL type).
• You use a legacy media format (such as Real Media) that is not supported by the VDA's multimedia player with multimedia redirection.
• The application for the content type is used by only a small number of users who already have the application installed on their user device.
• The VDA cannot access certain web sites (for example, web sites internal to another organization).

Compliance

You can use host to client redirection for compliance in the following use cases:

• The application or content licensing agreement does not permit publishing via the VDA.
• Organizational policy does not permit a document being uploaded to the VDA.

Some situations are more likely in complex environments, and also if the user device and the VDA belong to different organizations.  

Environments may have many different types of user devices.

Use the following examples to help guide your content redirection approach.

Host to client redirection is supported by Citrix Receiver for Windows, Receiver for Mac, Receiver for Linux, Receiver for HTML5, and Receiver for Chrome.

To use host to client redirection, the user device must have a web browser, multimedia player, or other application that is suitable for the content.  If the user device is a desktop appliance, thin client, or zero client, confirm that it has suitable applications and is sufficiently powerful.

User devices enabled for Local App Access use a different mechanism for content redirection, and do not require host to client content redirection.

You can use Citrix policies to prevent host to client content redirection for unsuitable devices.

Host to client redirection is used when URLs are:

• Embedded as hyperlinks in an application (for example, in an email message or document).
• Selected through a VDA application's menus or dialogs, provided that the application uses the Windows ShellExecuteEx API.
• Entered in the Windows Run dialog.

Host to client redirection is not used for URLs in a web browser (either in a web page or entered in the address bar of the web browser).

When host to client content redirection is enabled, the app that is used to open the URL depends on the configuration of the user device for both the URL type and the content type.  For example:

• An HTTP URL with an HTML content type will open in the default web browser.
• An HTTP URL with a PDF content type might open in the default web browser, or it might open in another application.

This user device configuration is not controlled by host to client content redirection.  If you do not control the configuration of the user device, consider using Flash redirection and multimedia redirection, rather than host to client content redirection.

The following URL types are opened locally through user devices when host to client redirection is enabled:

• HTTP (Hypertext Transfer Protocol)
• HTTPS (Secure Hypertext Transfer Protocol)
• RTSP (Real Player and QuickTime)
• RTSPU (Real Player and QuickTime)
• PNM (Legacy Real Player)
• MMS (Microsoft Media Format)

You can change the list of URL types for host to client redirection, to remove and add URL types, including custom URL types.

Enabling host to client redirection starts with enabling a Citrix policy setting.

The Host to client redirection policy setting is located in the File Redirection policy settings section. By default, this setting is disabled.

In addition, you may need to set registry keys and Group Policy for the server VDAs, depending on the VDA's OS.

• If the server VDA is Windows Server 2008 R2 SP1, you do not need to set registry keys or Group Policy.
• If the server VDA is Windows Server 2012, Windows Server 2012 R2, or Windows Server 2016, you must set registry keys and Group Policy.

1. Copy the text between "Reg file start" and "Reg file end" below, and paste it in Notepad.
2. Save the Notepad file with "Save As" as type All Files and the name ServerFTA.reg.
3. Distribute the ServerFTA.reg file to the servers using Active Directory Group Policy.

Create an XML file. Copy the text between "xml file start" and "xml file end" below, paste it in the XML file, and then save the file as ServerFTAdefaultPolicy.xml.

From the current Group Policy Management Console, navigate to: Computer configuration > Administrative Templates > Windows Components > File Explorer > Set a default associations configuration file, and provide the ServerFTAdefaultPolicy.xml file you created.

To change the list of URL types for host to client redirection, set the following registry key on the server VDA.

Key:  HKLM\Software\Wow6432Node\Citrix\SFTA

To remove URL types from the list, set DisableServerFTA and NoRedirectClasses:

Name: DisableServerFTA
Type: REG_DWORD
Data: 1

Name: NoRedirectClasses
Type: REG_MULTI_SZ
Data: Specify any combination of the values: http, https, rtsp, rtspu, pnm, or mms.  Enter multiple values on separate lines. For example:

http

https

rtsp

To add URL types to the list, set ExtraURLProtocols:

Name: ExtraURLProtocols
Type: REG_MULTI_SZ
Data: Specify any combination of URL types. Each URL type must include the :// suffix; separate multiple values with semicolons. For example:

customtype1://;customtype2://

To enable host to client redirection for a specific set of web sites, set the following registry key on the server VDA.

Key:  HKLM\Software\Wow6432Node\Citrix\SFTA

Name: ValidSites
Type: REG_MULTI_SZ
Data:  Specify any combination of fully-qualified domain names (FQDNs).  Enter multiple FQDNs on separate lines.  An FQDN may include a wildcard in the leftmost position only.  This matches a single level of domain, which is consistent with the rules in RFC 6125.  For example:

www.example.com

*.example.com