VNC (Virtual Network Computing) enables us to access the GUI of a remote system over a secured network. The VNC client installed on a local system captures the input events of a mouse and keyboard and transfers them to the remote VNC server. Those events are executed on a remote system and the output is sent back to the client. VNC is a desktop sharing tool and is generally used to access the desktop system for remote administration and technical support.
With Ubuntu server, we rarely need a desktop environment. However, if you are a newbie administrator or quite unfamiliar with the command line environment, then GUI becomes a handy tool for you. Plus, you may want to deploy a shared remote desktop environment where people can collaborate with each other. This recipe covers the installation of the VNC server on Ubuntu Server 14.04. We will install a GUI component that is required by VNC and then install and configure the VNC server.
Getting ready
You will need access to a root account or an account with sudo privileges.
How to do it…
The Ubuntu server and cloud editions generally ship with a minimal installation footprint and do not contain GUI components. We will use Gnome-core as our desktop component. Gnome-core is a part of an open source desktop environment.
Access the server shell and use the following command to install gnome-core:
$ sudo apt-get update
$ sudo apt-get install gnome-core -y
This will take some time as the command needs to download a bunch of components and install them.
Once Gnome is installed, we can proceed with VNC server installation using the following command:
$ sudo apt-get install vnc4server -y
When installation completes, start a new VNC session by using the following command:
$ vncserver
As this is the first time we have started VNC, you will be prompted to set up a password. This session will also create a few configuration files required for VNC. Your screen should look similar to the screenshot below:
Next, we will edit the default configuration files created by our first session, kill the VNC process, and then edit the configuration file:
$ vncserver -kill :1
Killing Xvnc4 process ID 2118
Edit the default configuration file and set it to use the Gnome session. Open ~/.vnc/xstartup and uncomment or add the following line to it:
$ nano ~/.vnc/xstartup
#!/bin/sh
# Uncomment the following two lines for normal desktop:
unset SESSION_MANAGER
# exec /etc/X11/xinit/xinitrc
#[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
#[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
#xsetroot -solid grey
#vncconfig -iconic &
#x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#x-window-manager &
metacity &
gnome-settings-daemon &
gnome-panel &
Optionally, disable the Gnome startup script. This will stop Gnome from starting with a system boot and you will see a CLI login instead of the new Gnome-based graphical login screen. Open /etc/init/gdm.conf and comment out the following lines:
$ sudo nano /etc/init/gdm.conf
#start on ((filesystem
# and runlevel [!06]
# and started dbus
# and plymouth-ready)
# or runlevel PREVLEVEL=S)
Save all modifications in configuration files and start a new VNC session. This time, we will add screen resolution and color depth options:
$ vncserver -geometry 1366x768 -depth 24
Next, from your local system, install the VNC client software and open it. I have used the TightVNC client. Enter your server IP address and a VNC desktop number to be connected. Here, we have created a single session to a sample IP address, which will be 192.168.0.1:1:
Click Connect; you will be prompted for a password to authenticate your session:
Enter the password that we created while starting the first session. You should see a desktop screen with a basic Gnome theme. The following is the scaled screenshot of the VNC viewer:
How it works…
VNC works with a client-server model. We have installed the VNC server daemon on our Ubuntu Server and a client on the local system. The server daemon communicates with the GUI buffer or frame buffer on the server side and transfers that buffer data to the client. The client renders that buffer in specially designed software called the VNC viewer. In addition to rendering the remote buffer, the VNC client or viewer captures mouse and keyboard (input) events happening over the client window. Those events are then sent to the VNC server, which applies them to the current graphics frame and any updates are sent back to client.
The pevious example uses simple Gnome-core components. This is a basic graphics suite which contains graphics drives, plus some other tools such as the Firefox browser and an instant messaging client. You can even choose to have a limited setup and install selective, required selected required Gnome packages as follows:
$ sudo apt-get install gnome-panel gnome-settings-daemon \
metacity nautilus gnome-terminal
This GUI does not match the one provided by Ubuntu Desktop. If you prefer to have the same experience as Ubuntu Desktop, you can separately install a package, ubuntu-desktop:
$ sudo apt-get install ubuntu-desktop
VNC does support multiple sessions to a single server. You may have noticed in the connection address used previously that we used :1 to represent the first session or display. This is shorthand for the full port number, which is 5901 for the first session, 5092 for the second, and so on. You can use the full port or just the last digit to refer to a session. Notice the change in desktop number when we start multiple VNC sessions:
Additionally, you can start a new VNC session for different users with its own password. Simply log in or switch (su user1) to the user account, start vncserver, set the password, and you are done.
See also
How VNC works on Stack Overflow - http://stackoverflow.com/questions/4833152/how-realvnc-works
