Once the VNC session is established, all VNC data exchange between the client and the remote computers is unencrypted. A malicious user might be able to spoof your VNC data, thus allowing the person to gain access to your computer. VNC software usually contains a VNC server and a VNC viewer program.

Secure Shell or SSH is a network protocol that allows data to be exchanged between two computers over an encrypted secure channel. PuTTY is a popular and easy to use free SSH client.

Cygwin is an emulation of the Linux/UNIX-like environment and OpenSSH for Windows.

There are free software available for you to download from the Internet to tunnel VNC traffic over SSH connection.

You will need:

• Cygwin
• RealVNC
• PuTTY
• TCP port 22 enabled at the remote computer

Install Cygwin on the remote computer

Login as Administrator.

Create a folder called c:\cygwin

Download the Cygwin setup file and save it in c:\cygwin folder.

Double click and run the Cygwin setup file.

Type c:\cygwin for the “Local Package Directory”.

Click the little View button for “Full” view.

Find the package “openssh“, click on the word “Skip” so that an “X” appears in the column.

Find the package “tcp_wrappers“, click on the word “Skip” so that an “X” appears in the column.

Find the package “zlib“, click on the word “Skip” (should be selected already) so that an “X” appears in the column.

Click “Next” to begin installing Cygwin and SSH.

Right click My Computer > Properties > Advanced > Environment Variables

Click the “New” button to add a new entry to System Variables:

Variable name: cygwin
Variable value: ntsec

Click the “OK” button.

Right click My Computer > Properties > Advanced > Environment Variables

Select the “PATH” variable and click the “Edit” button.

Append ;c:\cygwin\bin to the end of the Variable value.

Click the “OK” button.

Double click the Cygwin icon to open a cygwin window.

At the prompt, type ssh-host-config -y (the “-y” option automatically answers “yes” to the three questions below)

If the script asks about “privilege separation”, answer yes
If the script asks about “create local user sshd”, answer yes
If the script asks about “install sshd as a service”, answer yes

When the script asks about “CYGWIN=”, answer ntsec

To start the sshd service, open a Cygwin window and type either one of the following commands:

net start sshd
cygrunsrv ––start sshd

To stop the sshd service, open a Cygwin window and type either one of the following commands:

net stop sshd
cygrunsrv ––stop sshd

To harmonize Windows user information with Cygwin, open a Cygwin window and type the following commands, one line at a time:

mkpasswd ––local > /etc/passwd
mkgroup ––local > /etc/group

To test your sshd installation, open a Cygwin window and type the following command:

whoami

The current username should be displayed.

ls -h /cygdrive/c

You should see a directory listing.

Type exit at the command prompt to exit the Cygwin SSH session.

Install the VNC Server program

Download the RealVNC setup file on the computer to be controlled remotely.

Double click and run the RealVNC setup file.

Select the checkbox for VNC Server.

Click “Next” to begin the installation.

Type a VNC password when asked so that you will be prompted to enter a password every time you establish a VNC session.

Install the VNC Viewer program

Double click and run the RealVNC setup file on the computer you are using to control the remote computer desktop.

Select the checkbox for VNC Viewer.

Click “Next” to begin the installation.

Configure and run the PuTTY program

Double click and run the PuTTY program file on the computer you are using to control the remote computer desktop.

At the “Session” category in the tree menu, Type the Host Name or IP Address of the remote computer.

The Port should be default to 22 and the Connection type should be default to SSH.

Click the “SSH” category to expand the tree menu, and select “Tunnels”.

Add these entry below the “Add new forwarded port”:

Source port: 5900
Destination: 127.0.0.1:5900

Select the default values as “Local” and “Auto“.

Click the “Session” category in the tree menu.

Type a name at the “Saved Sessions” and click the “Save” button.

Click the “Open” button to establish a new SSH session to the remote computer.

Type the Windows username and password to login.

Leave the PuTTY program window open.

Run the VNC Viewer program

Double click and run the VNC Viewer program.

Type localhost or 127.0.0.1 and click “OK” to connect.

The VNC session should be tunelling through the SSH connection by now.

You can verify it by closing the SSH session. The VNC connection will be disconnected immediately too.

SSH, The Secure Shell

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