How to detect, from browser, if user is running in Remote Desktop session?

Question

Is there a ways to check inside a browser (e.g. javascript) if the user is running inside a Remote Desktop session?

If the user is running their browser inside a Remote Desktop (i.e. Terminal Services), i want to disable animations on the web-site.

If this were a native application, as opposed to a web-site, i could perform this checking using:

//Native code
isRemoteSession = GetSystemMetrics( SM_REMOTESESSION );

or

//Managed Code:
isRemoteSession = System.Windows.Forms.SystemInformation.TerminalServerSession;

Is there a similar check that can be done inside the browser?

Note: Assume for the purposes of this discussion that the browser we're talking about is Internet Explorer 8.

Update One: Perhaps something in How can you get the terminal service client machine name from javascript?

+1 because it would be a great usability enhancement for many sites. — Matteo Italia, Sep 03 '11 at 19:45

Maxy-B · Answer 1 · 2013-04-12T23:12:21.980

My solution is to use CSS @media queries for minimum and maximum values of the color media feature. Based on experiment, RDP only seems to have 5 bits per color, rather than the full 8 bits per color of your typical desktop.

This solution is, of course, not perfect, because you'll get lots of false positives from people who aren't on RDP, but just happen to have low color-depth displays. However:

If you are in a relatively controlled environment like a corporate intranet, you might feel more confident that "low color depth" = "RDP".
Many of the visual elements that need adjusting for RDP on a web-page, need adjusting precisely because of the low color depth (gradients, fade outs, animation, etc.), and so it actually makes sense to test for color depth rather than RDP per se.

Here is an example that works for me in recent version of Firefox and Chrome. See the screenshot below.

<!DOCTYPE html>
<html>
    <head>
        <title>Test RDP detection</title>
        <style type="text/css">
            @media all { li.color { display: none; } }
            @media all and (min-color: 1) { li.color.color-depth-1 { display: block; } }
            @media all and (min-color: 2) { li.color.color-depth-2 { display: block; } }
            @media all and (min-color: 3) { li.color.color-depth-3 { display: block; } }
            @media all and (min-color: 4) { li.color.color-depth-4 { display: block; } }
            @media all and (min-color: 5) { li.color.color-depth-5 { display: block; } }
            @media all and (min-color: 6) { li.color.color-depth-6 { display: block; } }
            @media all and (min-color: 7) { li.color.color-depth-7 { display: block; } }
            @media all and (min-color: 8) { li.color.color-depth-8 { display: block; } }

            /* 5 bits per color seems to be the max for RDP */
            @media all and (max-color: 5) {
                .not-rdp { display: none; }
            }
            @media all and (min-color: 6) {
                .rdp-only { display: none; }
            }
        </style>
    </head>
    <body>
        <p>This page uses CSS <tt>@media</tt> queries to detect whether you
            are viewing it over RDP&mdash;heuristically, by looking at the
            color depth of your display.</p>

        <ul>
            <li class="color color-depth-1">Your display is not monochrome!</li>
            <li class="color color-depth-2">Your display has at least 2 bits per color.</li>
            <li class="color color-depth-3">Your display has at least 3 bits per color.</li>
            <li class="color color-depth-4">Your display has at least 4 bits per color.</li>
            <li class="color color-depth-5">Your display has at least 5 bits per color.</li>
            <li class="color color-depth-6">Your display has at least 6 bits per color.</li>
            <li class="color color-depth-7">Your display has at least 7 bits per color.</li>
            <li class="color color-depth-8">Your display has at least 8 bits per color.</li>
        </ul>

        <p>You are <span class="not-rdp">not</span> using RDP.</p>
        <p class="rdp-only">This is only visible over RDP.</p>
    </body>
</html>

screenshot showing test page with and without RDP

Yet another approach along these lines is to use javascript to examine the value of the screen.colorDepth variable.

Note that the color depth is configurable in the RDP client: see the Advanced/Display/Colors dropdown. — Ben Voigt, Aug 26 '15 at 13:46
Just created a fiddle for this for people to test quickly: https://jsfiddle.net/7cqqpeqe/ - doesn't seem to work as a method any more though. — PhonicUK, Jun 05 '16 at 12:45
This doesn't seem to work in Chrome but does work in Firefox at least. There's also a javascript function to test the colordepth: http://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_screen_colordepth — Matthew Lock, Oct 05 '16 at 08:57

score 6 · Accepted Answer · answered Jun 07 '20 at 12:15

6

You can use the following media query:

@media screen and (prefers-reduced-motion: reduce) { . . . }

This condition can also hold for non-RDP sessions, but as your intention is to disable all animations, this type of query is probably exactly what you're looking for.

answered Jun 07 '20 at 12:15

Ercksen

668
9
23

1

Tested it and it works. Inside an RDP session, Chrome 83 uses `reduce`. It turns on `reduce` even if you turn on all visual experience effects, including *Menu and window animation*. Internet Explorer 11 and Edge don't set however. – Ian Boyd Jun 07 '20 at 14:22
@IanBoyd Does this method still work? I tried to replicate the results without any luck. – CodeSamurai777 Sep 16 '20 at 13:45
@CodeSamurai777 It does still work [MDN example](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-reduced-motion) (Chrome 85, Edge 85) – Ian Boyd Sep 16 '20 at 14:26
@IanBoyd May I ask what kind of RDP session did you test it on? I have tried TeamViewer and Windows RDP without luck. – CodeSamurai777 Sep 16 '20 at 16:18
@CodeSamurai777 Browsed to the page while using RDP to connect to my work PC from home. – Ian Boyd Sep 16 '20 at 19:42
I randomly stumbled upon this media query and the fact that Chrome uses it on RDP by seeing the React logo in their default app wasn't spinning – maaw Nov 30 '21 at 15:42

score 1 · Answer 3 · edited May 23 '17 at 12:08

1

You can probably expose the detection code via an ActiveX or BHO (e.g. assign a property to the window object in BHO) if you use IE.

Otherwise if you are using an ActiveX player to play animation, check the player's documentation to see if it automatically adjust frame rate under remote desktop.

You can always offer a low bandwidth version of your web site and instruct the user choose the web site instead of the regular web site if the video playback is not satisfactory.

For tips in writing a terminal service-aware graphics app, check graphic effects consideration, and the general performance guidelines

edited May 23 '17 at 12:08

Community

1
1

answered Sep 03 '11 at 19:25

Sheng Jiang 蒋晟

15,125
2
28
46

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"Let the user choose a low bandwidth version" is the correct answer. – Ben Voigt Sep 03 '11 at 19:48
Ben, not really as that still requires loading the page once before you can choose. Also, the needed bandwidth isn't really the problem over RDP, it's animations, large images, etc. since those make navigating a site nigh-unusable via RDP (since the display updates interfere with interaction). – Joey Sep 13 '12 at 14:02

score 0 · Answer 4 · answered Oct 02 '10 at 15:16

0

Perhaps you can read the SESSIONNAME environment variable? For a console session it should be CONSOLE and for an RDP session it should be RDP-TCP followed by a number.

answered Oct 02 '10 at 15:16

Remko

7,214
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Reading environment variables with client Javascript in the browser? I doubt it. – Joey Sep 03 '11 at 19:29

score 0 · Answer 5 · answered Nov 28 '10 at 12:18

0

I'm assuming you are talking about a specific company terminal server, not any terminal server. You could not serve animations to the specific IP address of the TS.

answered Nov 28 '10 at 12:18

Trevor Ian Peacock

824
5
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No, any terminal server. If you RDP to your home machine from at work, and go browsing my web-page: animations should not play. – Ian Boyd Nov 30 '10 at 17:01

score -2 · Answer 6 · answered Feb 25 '14 at 22:13

-2

This should not be done or decided by your application. On RDP client (like MS RDC), user can choose to disable animations etc. User can also disable these on server side (Terminal server or RDP host)

answered Feb 25 '14 at 22:13

user186188

5
1

3

The RDP connection performance options (such as animations, wallpapers, etc) are not exposed to in-browser applications, and browsers will render CSS/JavaScript animations regardless of RDP settings. Until there is an API exposed to see if animations and other features should be disabled in a web-application all we can do are little tricks to detect the environment. – Dai Aug 25 '17 at 04:22

How to detect, from browser, if user is running in Remote Desktop session?

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