Blackout local screen

[Joe Ammann]

[ On Thursday, June 1, 2000 at 10:29:26 (+0100), "Peaks, Jeremy" <Jeremy.Peaks "at" maff.gsi.gov.uk> (DN=M164210, ITD,    GUILDFORD, MAFF) wrote: ]
> Subject: Blackout local screen
>
 > I noticed in the history that disabling local keyboard and mouse
 > events has been implemented into VNC now, for NT machines.  Are
 > there any plans to implement a blackout local screen function in
 > the same way other products such as PC Anywhere do?  The reason I
 > ask is because we are concidering using VNC to give us remote
 > control over NT servers scattered around the country, but we do not
 > want the scenario where a user is in the same room as the server
 > and see's everything that is happening.  Such an event would cause
 > a security risk.  Any ideas?

I had to do this for a security critical environment in a bank. Not
being a Windows programmer, I quickly got bored trying to activate
DPMS features on Windows NT. To me, it looked like it was _very_
graphics card hardware dependent.

I got help from a commercial company (Entech) which has a product
called PowerStrip. They extracted for me the "Power Off Display"
feature into a NT driver and a DLL. This DLL basically has one
function: Turn power off and on.

This solution works for me quite well - but as I said, it is
commercial. If you're interested, inquire to Ashley Saldana
<support "at" entechtaiwan.com> for availabilty. Quote my name so that they
know what you're talking about.

Some problems I met down the line:

1) Some cards to not work at all, because their PowerManagement
   features are broken in the card BIOS (I can not personally confirm
   this quote, because I know too little about these topics. Ashley
   said so ;-)

2) I had the problem that when doing Ctrl-Alt-Del, some windows
   internal function seem to turn on the screen again. I had to change
   WinVNC to re-apply the "turn off monitor" when a desktop or screen
   resolution change was detected.

3) I had also the problem when the screen saver kicked in, while a
   connection was established. When VNC client then moved something,
   the screen saver obviously was deactived, and that caused again the
   montitor to become active again. The only thin I could find to
   solve this was to start a thread on connection establishment, that
   every once in a while just makes sure that the screen is turned off
   again.

   Maybe some Windows knowledgable kind soul has a better solution for
   that ;-)

Tell me if you'd like more infos. I can also post source and/or
patches, but they won't be of much help without the DLL from Entech.

Regards, Joe
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