Setting it up (concurrent sessions)
There is a huge difference between Windows Home and Windows Pro/Ultimate. Most of this relates Pro/Uptimate systems. RdpWrap (link below) allows connecting to a concurrent session in Home systems, too.
Once in a while Windows Updates might reset the configuration and you must re-run the setup.
How to shadow in Windows 7?
If you have set up RDP, open Task Manager > Processes tab > Elevate it: click on Show processes from all users > Click on Users tab > Right-click on the user to be shadowed > Remote Control.
You can set the desired access rights in Group Policy > gpedit.msc
Local Computer Policy > Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktio Session Host > Connections > Set rules for remote control of Remote Desktop Services user sessions: Enable the configuration and select the desired level of control and permission.
How to shadow in Windows 10?
Shadowing activated from the mstsc command line with options -- check mstsc /help
Configure access rights from Group Policy (see above) or from RDPConf.exe of RdpWrap package.
It takes a lot of typing each time to start shadowing. To make it easy, I put a file shadow.bat in Windows System32 directory with the following instructions:
@echo off
for /f "tokens=3" %%a in ('qwinsta ^| find "console"') do set id=%%a
mstsc /shadow:%id% /control /noconsentprompt
That allows opening an elevated command prompt and just type as easy as
shadow <username>
1@Juha, Your link is broken. – Pacerier – 2015-02-27T18:29:56.263
@purefusion, Still, you couldn't have access to the task manager unless you are already logon to the system as another user. There doesn't seem to be a way to directly remote-connect to a shadow session. – Pacerier – 2015-02-27T18:31:09.327
It's been so long, I don't remember what steps actually worked, but I and many others are really starting to dislike linked answers. Sure, link to things, but also extract the content that is relevant and post it in your answer. Nevertheless, thankfully Archive.org has come to the rescue. https://web.archive.org/web/20110312031655/http://thegreenbutton.com/forums/p/52888/238449.aspx & https://web.archive.org/web/20091207063110/http://forums.firedaemon.com/accessing-shadow-console-via-t397.html?s=19e3ca1081d428468ecc8e01e1b4d781&;
– purefusion – 2015-03-04T10:09:41.487Also interesting: http://forums.firedaemon.com/accessing-shadow-console-via-t397.html
(couldn't send two links in my answer since I don't have enough reputation :D, weird limitations)
1Just wanted to follow up and let you know that I did indeed get it working. After sifting through all the posts in that Green Button thread you linked to, I found that all I needed was the tip in the very last post: "In the future, if you don't want to use the shadow command, you can just go into the "users" tab of the task manager. Then, right click a user's name and select shadow session or shadow user (I forget exactly what it says). But if you haven't changed the other settings, the other use will be prompted to allow you to take control first." – purefusion – 2011-01-21T05:38:51.220
Minus that last bit about the other user getting prompted... I didn't have that obstacle, fortunately. Maybe some settings did get changed, I'm not sure. In any case, I wanted to make sure I thanked you properly for pointing me in the right direction. Thanks a million! :) – purefusion – 2011-01-21T05:41:59.190