WinVNC on Windows 2000 Professional crashes when client conne cts

Neel, Steve SNeel "at"
Wed, 13 Jun 2001 20:58:10 +0000

I've seen exactly the same scenerio! I thought it was a problem with
ZoneAlarm Pro since the blue screen usually sites "vsdatant.sys". Anyway, if
I reboot the system and try to connect right away again... no problem.

Win2k Pro - Sp2
WinVNC 3.3.9
ZoneAlarm Pro 2.6


-----Original Message-----
From: Tyran Ormond [mailto:ormondt "at"]
Sent: Wednesday, June 13, 2001 2:18 PM
To: vnc-list "at"
Subject: Re: WinVNC on Windows 2000 Professional crashes when client

On 02:15 PM 6/13/2001 -0400, it would appear that Bruce Lilly wrote:
>Note that it is the machine running WinVNC (as a service) which
>crashes (immediate reboot), not the client running VNCviewer.
>I've had this problem intermittently over several versions of WinVNC
>and all service packs for Windows 2000 and on a couple of hardware
>The crash occurs immediately after the client tries to connect,
>before the client can pop up the password window.
>I suspect that part of the fault may lie in the VNCviewer client,
>as making some seemingly irrelevant changes there often affects
>whether or not the server crashes; I suspect that something that
>the client sends to the WinVNC server causes the latter to crash
>the OS (also, the server tends to crash when the VNC port is scanned
>by security software looking for open TCP ports).
>As an example of a change that affects crashing, recently I had a
>situation where connecting from one machine to another caused the
>machine running WinVNC to crash. It happened repeatably, every time.
>Connecting from a different client didn't cause the crash.  The
>only difference between the two was that the client which caused
>the server to crash was using a FQDN (specifically, "")
>for the connection to the server, while the client that didn't cause
>the server to crash used a nickname ("bog:0").  I changed the other
>client to also use the nickname, and I've now connected to the server
>from that client at least a half dozen times with no crash. (later,
>it crashed again).
>I have enabled full logging on one of the WinVNC servers in the hope
>that there may be something informative written prior to a crash.

I experience the same immediate reboot crash on a Win2K Pro machine (but 
only on one of five) although both 3.3.7 and 3.3.9 exhibit the same crash, 
3.3.7 is much less frequent.  I am able to connect using the same settings 
after the target machine has rebooted and then experience no further 
problems until the machine has been allowed to sit idle for an extended 
period of time.  I had suspected it to be an interaction with the power 
save features of this machine and disabled them all to no effect.

Tyran Ormond
Programmer/LAN Technician
Central Valley Water
ormondt "at"
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