Logout on Windows 2008 disconnects VNC Session

Logout on Windows 2008 disconnects VNC Session

Postby vincentt » 2011-07-28 23:19

UltraVNC is installed as a Service on my Windows 2008 Standard Server. I am connected to the Server using VNCViewer 1.0.9.6 and see the desktop. The desktop usually runs on a non-admin user and when I need to perform an admin task, I need to log out the non-admin user and log-in back on the Server console as Administrator.

However when I select the Logout option in Windows 2008, the VNCViewer just closes and disconnects the current VNC Session. If I re-connect, I can see that the console has logged out and waiting with the Ctrl + Alt + Delete key to be pressed and once I do so I can proceed with my admin login. This is difficult as every time I need to logout, I need to re-connect again to the server.

This is seen in Windows 2008, Windows 2003 does not seem to be having this issue. I also see two "winvnc.exe" running under the SYSTEM account.

Any inputs to this one?
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Re: Logout on Windows 2008 disconnects VNC Session

Postby B » 2011-07-29 13:16

Honestly, I'm so used to these sort of problems I would be grateful that, in your case, you can get right back in simply by reconnecting.

Are you sure there's no application-level of WinVNC being started as the non-admin user logs in? (Startup folder, registry, etc.)
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Re: Logout on Windows 2008 disconnects VNC Session

Postby vincentt » 2011-07-29 19:12

I have seen that TightVNC does not disconnect when I do the same above process. However UltraVNC does disconnect. There are no application level WinVNC's running on the system, on admin mode nor in non-admin modes. This seems to be a bug with UltraVNC.

Also, why are there two process's of WinVNC, does that have anything to do with the disconnects?
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Re: Logout on Windows 2008 disconnects VNC Session

Postby vincentt » 2011-07-29 19:14

With the disconnect, the user has to connect back again which is not a very good way to manage the problem. I tried doing the same test with TightVNC and TightVNC holds good and does not disconnect.

Also I wanted to ask why are there two process's of WinVNC running on the system, both running as SYSTEM account. I verified that WinVNC is running only as a service and not in application mode.
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Re: Logout on Windows 2008 disconnects VNC Session

Postby B » 2011-07-30 04:09

I believe they split up UltraVNC into multiple services in order to better handle the Vista/Win7 security model.

For what it's worth I've had the "have to VNC back in after Windows logoff" problem ALL THE TIME with TightVNC (specifically with XP Home multi-user). So each person's mileage may vary.
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Re: Logout on Windows 2008 disconnects VNC Session

Postby vincentt » 2011-08-08 18:22

Are there any plans in UltraVNC to have a fix for the issue of disconnect? I believe it's a good security feature to disconnect when the user logs out, but can be bothersome when disconnect, the requirement to connect again.
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Re: Logout on Windows 2008 disconnects VNC Session

Postby YY » 2011-08-09 04:20

vincentt wrote:I believe it's a good security feature to disconnect when the user logs out, but can be bothersome when disconnect
This is not caused by UltraVNC, but is security feature introduced since Vista ... something related to Session Isolation.
(reference Connection to Win7 machine drops for details)

I believe Win2008 having this feature too.


vincentt wrote:Are there any plans in UltraVNC to have a fix for the issue of disconnect?
Have you tried what B suggested ?
The (VNCViewer|Option|Reconnect Number) is supposed to overcome this problem.

The reconnect is done in the background, and the VNCViewer WILL NOT be closed when you log off from the non-admin user, and then switch to the Win Logon Screen. You don't even aware the connection has been broken and reconnected.


vincentt wrote:I have seen that TightVNC does not disconnect when I do the same above process.
Rudi considered the cause may be ....
http://forum.ultravnc.info/viewtopic.ph ... 36&start=7
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Re: Logout on Windows 2008 disconnects VNC Session

Postby vincentt » 2011-08-10 16:52

Thanks YY, I did try with the Reconnect option in the vncviewer and that option works good. With no command line to support the reconnect makes it a little hard.

Is UltraVNC planning on having the reconnect option in the command line option soon?
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Re: Logout on Windows 2008 disconnects VNC Session

Postby YY » 2011-08-10 17:16

The VNCviewer already has this option in command line, i.e.

- autoreconnect --- the timeout in GUI (in second)
- reconnectcounter --- the reconnection attempts in GUI

For e.g.
Code: Select all
vncviewer.exe -autoreconnect 4 -reconnectcounter 5 xx.xx.xx.xx

this command instructs the vncviewer to connect to xx.xx.xx.xx,

Once connected, the viewer to try to autoreconnect if the connection is accidentally dropped.
The autoreconnect will be taken at every 4 seconds, and retry (if not able be connected again) for 5 times.
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