You can simply use any port scanner to scan your network on port 5900 for VNC Server because the default port for any VNC Server is 5900.
I’ve found a script based port scanner which claims to be a VNC Network Scanner. I believe you can also use to scan for other services since you can define both port and IP range to scan. This is something different to me because most of the port scanners out there are in executable(.exe) format.

This script has the extension of .wsf, which is Windows Scripting Host. The script makes use of function pointers hooked up to a programmatically generated Internet Explorer page to allow user input in a flexible environment while giving the advantages of the tighter security and lower overhead of WSH.

As you can see, the image below shows that this VNC Server scanner is being run on Internet Explorer and it’s not any compiled executable program.

SCAN4VNC may be run directly after the Winsocklib DLL is registered on your system. You can obtain the Winsocklib DLL file from the zip archive with the filename kvbWinsockLib.Dll. Running scan4vnc.wsf directly without registering the kvbWinsockLib.Dll will give you an error message “Error: 424 Microsoft VBScript runtime errorObject required”

You need regsvr32.exe to register the kvbWinsockLib.Dll. Follow the steps below to register kvbWinsockLib.Dll to your system.

1. Double click kvbWinsockLib.Dll file. You will get a caution prompt. Click on the “Open With…” button

2. Select the option “Select the program from a list” and click OK button.

3. Click on the Browse button to search for regsvr32.exe which is usually located at C:\Windows\System32\
TightVNC

4. After you located the regsvr32.exe, select to highlight the file and click on Open button.

5. You should get a prompt saying “DllRegisterServer in “C:\xxxxxxxxxxxxxxxxxx\kvbWinsockLib.Dll succeeded.”

The xxxxxxxxx is the location of your kvbWinsockLib.Dll file.

I tested using the script to scan for RealVNC server which I installed on another computer, and below is the report.

The reporting should be improved because if the RealVNC server service is running, it will show you “7“. For computer that doesn’t have RealVNC server, it will show you “Timeout“.

This time I used the script to scan on UltraVNC server. Also show “7“.

In my opinion, this script works but the scan result should be improved. I tried scanning port 80 which is WWW port, and the result also shows “7″. It seems like any active service will show “7″ in SCAN4VNC. The readme.txt file did say that this script is still in early beta demo and it’s FREE so we shouldn’t complain about it.

[ Download Scan4VNC ]

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