Linux Virtual Delivery Agent

Browser content redirection

Overview

The Linux VDA supports browser content redirection in Google Chrome. Browser content redirection provides the ability of rendering webpages in the allow list on the client side. This feature uses Citrix Workspace app to instantiate a corresponding rendering engine on the client side, which fetches the HTTP and HTTPS content from the URL.

Note:

You can specify which webpages are redirected to the client side by using an allow list. Conversely, you can specify which webpages are not redirected to the client side by using a block list.

This overlay web layout engine runs on the client instead of on the VDA and uses the client CPU, GPU, RAM, and network.

Only the browser viewport is redirected. The viewport is the rectangular area in your browser where content displays. The viewport does not include items such as the address bar, favorites bar, and status bar. Those items are still running in the browser on the VDA.

Image of viewport

System requirements

Windows client:

  • Citrix Workspace app 1809 for Windows or later

Linux VDA:

  • VDA operating system: Ubuntu 16.04, Ubuntu 18.04, RHEL 7.8,RHEL 8.2, RHEL 8.1, SLES 12.5
  • Browser on the VDA: Google Chrome v66 or later with the Citrix browser content redirection extension added

Configure browser content redirection

  1. In Citrix Studio, configure a policy that specifies an allow list of URLs that can use browser content redirection and a block list of URLs that cannot. Browser content redirection is set to Allowed by default.

    Image of browser content redirection set to allowed

    The Browser Content Redirection ACL Configuration setting specifies an allow list of URLs that can use browser content redirection.

    Image of Browser Content Redirection ACL Configuration being selected

    Image of setting an allow list

    The Browser Content Redirection Blacklist Configuration setting specifies a block list of URLs that cannot use browser content redirection.

    Image of setting a block list

    Note:

    The Linux VDA currently does not support the Browser Content Redirection Proxy Configuration setting.

  2. For the browser on the VDA to detect whether a URL (being navigated to) matches an allow list or a block list, add the Citrix browser content redirection extension from the Chrome Web Store. Click Add to Chrome on the VDA.

    Important:

    The extension is not required on the client. Add it only on the VDA.

    Chrome extensions are installed on a per-user basis. Updating a golden image to add or remove an extension is not required.

    Image of adding the Citrix browser content redirection extension from the Chrome Web Store

If a match to a URL is found in an allow list (for example, https://www.mycompany.com/) but not in any block list, a virtual channel (CTXCSB) instructs the Citrix Workspace app that a redirection is required and relays the URL. Citrix Workspace app then instantiates a local rendering engine and displays the website.

Citrix Workspace app then blends back the website into the virtual desktop browser content area seamlessly.

Image of viewport and client

  1. Icon of the Citrix browser content redirection extension

    The color of the extension icon specifies the status of the Chrome extension. It is one of the three colors:

    • Green: Active and connected
    • Gray: Not active/idle on the current tab
    • Red: Broken/Not working
  2. Viewport rendered on the client or blended back to the virtual desktop
  3. Linux VDA
  4. Windows client

Redirection scenarios

Here are scenarios of how the Citrix Workspace app fetches content:

Image of redirection scenarios

  • Server fetch and server render: There is no redirection because you did not add the site to the allow list or the redirection failed. We fall back to rendering the webpage on the VDA and use Thinwire to remote the graphics. Use policies to control the fallback behavior. This scenario causes high CPU, RAM, and bandwidth consumption on the VDA.
  • Client fetch and client render: Because the Citrix Workspace app contacts the web server directly, it requires Internet access. This scenario offloads all the network, CPU, and RAM usage from your Citrix Virtual Apps and Desktops site.

Fallback mechanism

There might be times when client redirection fails. For example, if the client machine does not have direct Internet access, an error response might go back to the VDA. In such cases, the browser on the VDA can then reload and render the page on the server.

Browser content redirection and DPI

WARNING:

Editing the registry incorrectly can cause serious problems that might require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.

When using browser content redirection with the DPI (scaling) set to anything over 100% on the user’s machine, the redirected browser content screen displays incorrectly. To avoid this issue, do not set the DPI when using browser content redirection. Another way to avoid the issue is by disabling browser content redirection GPU acceleration for Chrome by creating the following register key on the client:

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Citrix\HdxMediaStream
Name: GPU
Type: DWORD
Data: 0