VNC SingleClick

VNC SingleClick is a program that lets a person run a small (166k) program in order to let another user see their computer screen and/or control their computer. It’s way useful.

Here are notes I took on how to set it up (these instructions were ripped from a doc I wrote for another purpose. Sorry if it’s slightly unintelligible)

Set up a DNS alias with

Quick setup instructions for installing a VNC Single-Click client and server

1. Install Ultra VNC 101 on the computer that’s going to watch other people’s screens.
2. Copy C:\Program Files\ultravnc\plugin\MSRC4Plugin.dsm to C:\Program Files\ultravnc to facilitate the rc4 key system.
3. Put rc4.key here: C:\Program Files\ultravnc\rc4.key (you’ll have to generate this key, look elsewhere for info on this)
4. Create a shortcut like so: Target: “C:\Program Files\ultravnc\vncviewer.exe” -listen 6800 -viewonly -dsmplugin MSRC4Plugin.dsm Start in: “C:\Program Files\ultravnc”
5. Put a hole in your local firewall, allowing TCP traffic on port 6800 from the internet to get to your desktop
6. Start VNC using the new shortcut.
7. Give the small VNC Single Click executable to someone. Tell them to run it and double-click on the line that reads “Let Lee see my computer screen”
8. You should now be able to see their computer screen
9. You can control their screen by going to the Options screen and unchecking “View only”. You can copy files to and from their computer with the VNC file transfer facility.

How to use VNC to see customers’ computers
To view someone’s screen to give them technical support or whatnot, do the following:

Remote desktop as Administrator into [the machine you set up as the VNC viewer]. Make sure VNC is running in listen mode, listening on port 6800 (that’s not the standard VNC port). There should be an icon in the system tray indicating this. If not, double-click on the VNC icon on the desktop to start it.

Ask the customer to run the VNC Single-click software you gave them.

Tell them, “On the left side, you should see something that says, ‘Let Lee see my computer screen’. Go ahead and double click on that line.”

When they do, you’ll see an acknowledgment message on your screen. Click “Yes” and you’ll be able to see their screen.

By default, you can only see their screen. If you click on “Show Connection Options” in the upper left, you can uncheck “View only” mode to control their computer. Use sparingly, else the customer may get freaked out.

How to set VNC up from Scratch

We’re trying to install with RC4 encryption here. You can skip some steps if you’re not trying to encrypt the connection. (though I don’t currently note which steps you can skip. Sorry)

Install UltraVNC on the machine on which you want to see customers screens on. Get UltraVNC 1.0.1 Setup

If I remember correctly, you have to move MSRC4Plugin.dsm from C:\Program Files\ultravnc\plugin to C:\Program Files\ultravnc

Start VNC using a shortcut like this: Target: “C:\Program Files\ultravnc\vncviewer.exe” -listen 6800 -viewonly -dsmplugin MSRC4Plugin.dsm
Start in: “C:\Program Files\ultravnc”

Creating the Single Click executable

We are going to create a small .exe that customers can run so we can connect to them.

You’ll gather together several files, zip them into a file called, upload it to a VNC server and get back the finished program.

There is a program you can download that will do the compiling locally but I haven’t used it yet.


* Local .exe compiler
* Another Local .exe compiler link
* Single Click homepage
* Single Click Creator

RC4 key

This will protect your sessions with an RC4 key. RC4 isn’t the best encryption but it’ll stop casual man-in-the-middle attacks. There is no better encryption readily available.

* To Generate a Key file – Start the UltraVNC Viewer. Select the MSRC4Plugin_NoReg. Click on the Configure button. In the “Generate New Key File section, note the path and name of the key to be generated. (The default is “new_rc4.key”) Select the key size. Click on “Gen Key”.
* Put the key on your machine here: C:\Program Files\ultravnc\rc4.key
* Put the key in your

What goes in

See for good info on this

* background.bmp – a vertical line with some color.

* helpdesk.txt – The meat of it. Here is what Lee Support uses:

           Lee's Remote Computer Viewer

Let Lee see my computer screen.
-plugin -connect -noregistry

Double-click the link above.

When started, Lee will be able to

see and control your computer screen.

When finished, Lee

won't have access to your computer

unless you run this program again.

Lee Support



Establishing connection ...

Lee's Remote Computer Viewer is attempting

to connect to Lee.
If it can't connect after 3 minutes, it will exit.


Lee can now see your screen.

You can break the connection at any time

by right-clicking this icon and clicking 'Close'.


* icon1.ico – The “Other people cannot yet see your screen” icon

* icon2.ico – The “Other people can now see your screen” icon

* logo.bmp – an image that will be seen on the right side of the customer’s executable window. This must be

* rc4.key – the key generated elsewhere. This key will be in both the customer’s executable and on the listening VNC.

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