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Author Topic: Multiple Windows XP Sessions  (Read 11024 times)

Dakusan

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Multiple Windows XP Sessions
« on: September 28, 2009, 05:31:36 am »

Original post for Multiple Windows XP Sessions can be found at https://www.castledragmire.com/Posts/Multiple_Windows_XP_Sessions.
Originally posted on: 08/13/08

All of the Windows lines of OSs from XP through Windows Server 2003 (or 2005 or 2007?) are, to my knowledge and IMO, basically the exact same thing, with just some minor tweaks and extra software for the more expensive versions. My version of XP Professional even comes with IIS (Internet Information Services - Microsoft’s web/ftp/mail server suite). One of my favorite XP hacks adds on a desperately needed functionality found only in Windows Server editions, which is allowing multiple user sessions on a machine at once. This basically means allowing multiple people to log onto a machine at the same time through Remote Desktop (Microsoft’s internal Windows VNC client). I find the most useful function by far of this is the “Remote Control” feature, which allows a second logged in user to see exactly what is on the screen of another session, and if permissions are given, to take control of it. This is perfect for those people whom you often have to trouble shoot computer problems for, eliminating the need for a trip to their location or 3rd party software to view their computer.

This hack requires a few registry modifications, a group policy modification, and a DLL replacement. The DLL replacement was provided by Microsoft in early versions of XP SP2 when they were tinkering with allowing this feature in XP. I found the information for all this here a number of years ago and it has provided itself invaluable since. Unfortunately, this does not work on XP Home edition, just XP Professional. I tried adapting it once and wasted a lot of time :-\. The following is the text from where I got this hack.

Concurrent Remote Desktop Sessions in Windows XP SP2

I mentioned before that Windows XP does not allow concurrent sessions for its Remote Desktop feature. What this means is that if a user is logged on at the local console, a remote user has to kick him off (and ironically, this can be done even without his permission) before starting work on the box. This is irritating and removes much of the productivity that Remote Desktop brings to Windows. Read on to learn how to remove that limitation in Windows XP SP2

A much touted feature in SP2 (Service Pack 2) since then removed was the ability to do just this, have a user logged on locally while another connects to the terminal remotely. Microsoft however removed the feature in the final build. The reason probably is that the EULA (End User License Agreement) allows only a single user to use a computer at a time. This is (IMHO) a silly reason to curtail Remote Desktop’s functionality, so we’ll have a workaround.

Microsoft did try out the feature in earlier builds of Service Pack 2 and it is this that we’re going to exploit here. We’re going to replace termsrv.dll (The Terminal Server) with one from an earlier build (2055).

To get Concurrent Sessions in Remote Desktop working, follow the steps below exactly:

  1. Download the termsrv.zip file and extract it somewhere.
  2. Reboot into Safe Mode. This is necessary to remove Windows File Protection. [Dakusan: I use unlocker for this, which I install on all my machines as it always proves itself useful, and then usually have to do a “shutdown -a” from command line when XP notices the DLL changed.]
  3. Copy the termsrv.dll in the zip to %windir%\System32 and %windir%\ServicePackFiles\i386. If the second folder doesn’t exist, don’t copy it there. Delete termsrv.dll from the dllcache folder: %windir%\system32\dllcache
  4. Merge the contents of Concurrent Sessions SP2.reg file into the registry. [Dakusan: Just run the .reg file and tell XP to allow the action.]
  5. Make sure Fast User Switching is turned on. Go Control Panel -> User Accounts -> Change the way users log on or off and turn on Fast User Switching.
  6. Open up the Group Policy Editor: Start Menu > Run > ‘gpedit.msc’. Navigate to Computer Configuration > Administrative Templates > Windows Components > Terminal Services. Enable ‘Limit Number of Connections’ and set the number of connections to 3 (or more). This enables you to have more than one person remotely logged on.
  7. Now reboot back into normal Windows and try out whether Concurrent Sessions in Remote Desktop works. It should!

If anything goes wrong, the termsrv_sp2.dll is the original file you replaced. Just rename it to termsrv.dll, reboot into safe mode and copy it back.

The termsrv.dl_ file is provided in the zip is for you slipstreamers out there. Just replace that file with the corresponding file in the Windows installation disks.



I have included an old copy of the above web page, from when I first started distributing this, with the information in the hack’s zip file I provide.

If you want to Remote Control another session, I think the user needs to be part of the “Administrators” group, and don’t forget to add any users that you want to be able to remotely log on to the “Remote Desktop Users” group.

This is all actually part of an “Enhanced Windows XP Install” document I made years ago that I never ended up releasing because I hadn’t finished cleaning it up. :-\ One of these days I’ll get it up here. Some of the information pertaining to this hack from that document is as follows:

  • Any computer techy out there that has tried to troubleshoot over the phone knows how much of a problem/pain in the anatomy it is, and for this reason, I install this hack which makes it painless to automatically connect to a users computer through remote desktop, which can then be remotely viewed or controlled via their displayed console session.
  • I often use this hack myself when I am running computers without keyboards/mice, like my entertainment computer.  For a permanent solution for something like this though, I recommend a KM (Keyboard/Mouse) solution like synergy, which allows manipulating one computer via a keyboard and mouse on another.
  • Your user account password must also not be blank.  Blank passwords often cause problems with remote services.
  • The security risk for this is a port is opened for someone to connect to like telnet or SSH on Unix, which is a minimal risk unless someone has your username+password.
  • You have to have a second username to log into, which can be done under Control Panel > User Accounts, or Control panel > Administrative Tools > Computer Management > System Tools > Local users and Groups.
  • If you want the second user to be able to log in remotely, make sure to add them under Control Panel > System > Remote > Select Remote users, and also check “allow users to connect remotely to this computer”.
  • You also need to know the IP address of the user’s computer you want to connect to, and unfortunately, they are not always static.  If you run into this, you may want to use a DDNS service like mine.
  • You may also run into the unfortunate circumstance of NAT/Firewalled networks, which is beyond the scope of this document. Long story short, you need to open up port 3389 in the firewall and forward it through the router/NAT (this is the port for both remote desktop and remote assistance).
  • You may also want to change the port number to something else so a port scanner will not pick it up.  To connect to a different port, on the client computer, in remote desktop, you connect to COMPUTERIP:PORT like www.mycomputer.com:5050.
    • Registry Key: HKLM\System\CurrentControlSet\Control\TerminalServer\WinStations\RDP-Tcp\PortNumber - Set as your new port number
    • This requires a reboot to work.
    • Make sure you don’t provide a port that’s already used on the computer, and you probably shouldn’t make it a standard port either [21 [ftp], 25 [smtp], 80 [http], etc])
  • You can also log into their current console session by going to the task manager (ctrl+shift+esc in full screen, or right click taskbar and go to “task manager”) > Users > Right click username > Remote control
    • This will ask the user at the computer if they want to accept this.  To have it NOT ask them, do the following:
      • Start > Run > gpedit.msc [enter] > computer configuration > administrative templates > windows components > terminal services
      • Double click the option “Sets rules for remote control of terminal services user sessions”
      • Enable it, and for the “Options” setting, set “Full control without users permission”
  • If the ability for you to access a client’s computer without their immediate permission or knowledge is too “dangerous” for their taste, you may suggest/use Remote Assistance, which is more troublesome, but much more “secure” sounding.
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Dakusan

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Re: Multiple Windows XP Sessions
« Reply #1 on: January 28, 2010, 07:08:59 am »

Was doing a bit of poking around earlier because someone reported to me that the DLL I provided for this was reported by Kaspersky as having a Trojan. It is a very good chance that it's a false positive, as it's not the first I've had from Kaspersky (which I still trust the most as far as AVs go), but its not easy to check since the hex dump of it is completely different than the original (because the one I provided is theoretically from a beta of XP, not a hacked version).

This website however provides better versions of the DLLs because they are patched with minor assembly-level changes, so it is easier to confirm their non-malicious nature. I have confirmed that the changes for the XP SP2 DLL at the very least look clean (haven't checked the actual assembly, just assumptions from the hex dumps). I have not personally tested these yet, so I don't know as to if they actually work, but I will be trying them out as soon as the opportunity arises.
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