Enabling Concurrent Remote Desktop Sessions in Vista

At work, I do all of my development on a Windows 2003 box. I generally log in as a normal user, and then use Remote Desktop to concurrently log in as Administrator. This means that I’m relatively safe from malware when doing day-to-day stuff, but that I can still get hold of Administrator privileges when I need them.

This feature is only enabled on server editions of Windows. When you try to connect to Windows Vista (for example), you have to disconnect the currently logged-on user.

This is taken more-or-less, directly from here, so I can’t take any credit.

You’ll need a hacked termsrv.dll, as follows:

fc /b %SYSTEMROOT%\System32\termsrv.dll termsrv_new.dll
Comparing files C:\WINDOWS\SYSTEM32\termsrv.dll and TERMSRV_NEW.DLL
000150D8: 3B BA
000150D9: 91 00
000150DA: 20 01
000150DB: 03 00
000150DD: 00 90
000150DF: 0F 89
000150E0: 84 91
000150E1: 0C 20
000150E2: CA 03
000154BF: 43 90

(This one’s for Windows Vista Ultimate, x86 (i.e. 32-bit). And then you’ll need to install it, as follows:

cd /d %SYSTEMROOT%\System32
sc stop UmRdpService
sc stop TermService
takeown /f termsrv.dll
cacls termsrv.dll /G DOMAIN\User:F
ren termsrv.dll termsrv.dll.orig
copy path\to\termsrv_new.dll termsrv.dll
sc start TermService
sc start UmRdpService

Done.

Note that if you want to connect to localhost, you’ll need to run some kind of port forwarding utility, and you’ll need to connect to it via 127.0.0.2.