VNC connections fail with UltraVNC

[Brian Bergin]

When I have UltraVNC installed on customers' systems I'm unable to get the .vnc file to launch locally.  I get the attached error.  RDP and HTTP works perfectly, but we have hundreds of UVNC installs out there so any help here would be great.

Thanks...

[Christopher Bearman]

Brian,

This is a tricky issue, and I think that the fault is with the design of the UltraVNC client.

Ideally, we'd directly launch your VNC client for you. Unfortunately, you just can't do this from inside a browser (too much of a security risk - browser does not allow it).

Instead we provide a .vnc file that is understood by most VNC clients. Provided you click on the RUN option when downloading the file, you should get auto-connected.

I have verified that UltraVNC does understand these files. If you save it, and then manually open it from inside UltraVNC then everything works.

The problem, therefore, is the Windows File Association behavior of UltraVNC. When a windows application is associated with a filetype, and a file of that type is launched, the standard behavior is for Windows to launch the associated application using the .vnc file (in this case) as the first command line parameter. Unfortunately, UltraVNC requires the insertion of "-config" or "\config".

So windows tries to launch as :

  vncviewer connectionfile.vnc

Whereas UltraVNC wants:

  vncviewer -config connectionfile.vnc

In my opinion this is a fault in the design of vncviewer (UltraVNC). It supposedly works with windows file association launch because it has an option (-register) that is meant to install the association mapping for Windows. Having said that, it doesn't seem to do anything on my Windows Vista box and I cannot see how I would configure a permanent association that worked in the way it wants.

You may want to reference the following article for more information:

http://forum.ultravnc.info/viewtopic.php?t=14407

I suspect that this will be a case of won't work due to unsupported FileAssociation launch for UltraVNC. Having said this, i'm a mac guy and my windows skills are rusty, so maybe there is a way. If you find one let me know.

Unless you know of an easy way to bypass this problem that i've missed, i'd say you'll just have to cut and paste the link, or move to a different VNC client that does work properly with Windows file association. I think i've tested this with RealVNC client and it works fine (although I don't think the free version provides encrypted connections). It is worth noting that any VNC client *should* work with any VNC server so you should be able to use the client of your choice without changing the server running on your client's machines.

Let me know if this helps!

Chris.

[Brian Bergin]

Thanks!  Solved it.  You are indeed correct, UltraVNC doesn't correctly register .vnc file extensions in Windows.  By default it registers:

"C:\Program Files\UltraVNC\vncviewer.exe" "%1"

when in fact it needs to be:

"C:\Program Files\UltraVNC\vncviewer.exe" -config "%1"

I used "Types" from http://types.sourceforge.net/ to modify the file extension to add -config and now the .vnc file opens from a Web browser as well as from icons on the local disk correctly.

Thanks again...

[Christopher Bearman]

Brian,

Glad that helped. Nice to know that there's a way to fix the association as well. I'll forward your solution on to our Doc team and see if we can include a note for users of UltraVNC in our documentation.

Chris.

[dcorley]

Brian, you mentioned UltraVNC on hundreds of PCs. Is there a particular reason why you use UltraVNC over other VNC viewer alternatives? I'm trying  to understand the market utilization and preference of this and other RDP/VNC clients...there are a lot listed in wikipedia but no market share data that I have been able to find in limited research.

I'd appreciate yours and others insights on preferred RDP/VNC clients.

Dave

[Brian Bergin]

We first went to UVNC becuase it was fast.  We found it faster than many of the other flavours.  Then the real kicker was UltraVNC offered a "single click" option that's absolutely wonderful.  http://www.uvnc.com/pchelpware/sc/index.html  It allows us to have customers be able to give us remote access without admin rights (Webex and others require admin rights to install ActiveX or other code) and with no firewall changes on their end so it even works if the customer is in a hotel.  The compiled code is ~200k.  We use this every day many times/day to solve customer issues and to do training.  Of course, the TBA would eliminate the need for single click entirely!

[danny]

I have yet to get VNC to connect via the TBA.  I get and error "Failure to connect to Server"  I found this discussion and followed Brians suggestion and still cannot connect.  VNC is a must for us because we use it to interact with the customer for training or so the customer can so us problems they are having.  So it has to work for us to have an interest in Thunderbolt.  Also as a sidebar issue we need the ability to choose the resolution in RDP.  I use two monitors one large and one small so there are times I need to change the resolution so it will fit my small monitor without scroll bars.

[Marcos Hernandez]

Danny, can you confirm that you are trying to make it work from the OUTSIDE of the network? Meaning, you are not on the same LAN as the TBA and the target computer.

[Brian Bergin]

Marcos,

I'm seeing this too.  I had it working after "fixing" UltraVNC's setup and now it will open the .vnc file but it won't connect to the remote machine.  It's almost like the VNC service isn't running, but when I RDP to another machine I can VNC to the original one just fine.

[Marcos Hernandez]

OK, we'll take a look. What is the customer number?

[danny]

Try Customer 1050 and attemp to connect to NCS-TestPC and see if you get a login dialogue I do not.

[danny]

Hello Marcos,

I have tried it on the same lan and from the outside and get the same error.

[Michael Holloway]

Danny, I am able to establish a connection to that machine with VNC protocol on port 5900 (default) from my Mac using 'Chicken of the VNC' client. It doesn't paint a screen, and gives an authentication error as we would expect, because I didn't supply a password to connect. VNC uses just a password for authentication (not username/password) and this can be a different password than the default Windows account password, it's usually configured directly in the VNC server software.

Please verify that you are using the correct VNC password (which can be tested by RDP'ing to another machine on that network and then trying to VNC directly to that other machine), and let us know if that works. If so, then we need to look deeper to see what the portal might be doing to cause problems for your VNC client. Maybe an MTU issue.

-mike

[Brian Bergin]

VNC absolutely has the ability to authenticate to Windows' local or domain usernames.  Perhaps this is the problem.  I always set up VNC to authenticate this way as it will also allow Windows to use local security measures to lock out an account improperly used where VNC doesn't.

[danny]

Hello Marcos,

I am very familiar with the VNC password because I set it up but I never get to enter the password.  Soon as I click on open I get a VNC Message box that says "Failed to connect to server !" I have attached 3 screen shots

1. VNC Message Bos.rtf - Showing the error message

2. VNC Connection Box NonTBA -  Showing the VNC Conncetion Box when using local VNC Viewer.

3. VNC Connection BoxTBA - Showing an attempted connection using TBA.

Notice the VNC Connection Box NonTBA it show the port that being used to connect while the VNC Connection BoxTBA port is empty.

This may be the problem that the TBA Vnc is not using the port designated in the connection settings.

If you would like i can change the password on the system you attempted to connect to, to be the same as the Customer PW so you will be able to complete the test.