Install GNOME on CentOS and setup vnc server

# yum -y groupinstall “Desktop” “Desktop Platform” “X Window System” “Fonts”

You can also install the following optional GUI packages.

# yum -y groupinstall “Graphical Administration Tools”
# yum -y groupinstall “Internet Browser”
# yum -y groupinstall “General Purpose Desktop”
# yum -y groupinstall “Office Suite and Productivity”
# yum -y groupinstall “Graphics Creation Tools”
Finally, if you wanted to add the K Desktop Environment (KDE).
# yum -y groupinstall kde-desktop

When using yum groupinstall, the groupinstall option only installs default and mandatory packages from the group. There are times when you also want to include optional packages within a group. I have not figured out (yet) how to control which package types to install (group package “policy”) from the command-line using yum. The only method I know of to also include optional packages is to edit the /etc/yum.conf file and add the following to the [main] section:
group_package_types=default mandatory optional
The reason I mention this is because I wanted to install “Terminal emulator for the X Window System” (xterm) which is under the group “Legacy X Window System compatibility”. xterm happens to be an optional package and did not get installed until I added group_package_types=default mandatory optional to /etc/yum.conf.

# yum -y groupinstall “Legacy X Window System compatibility”

I did find a plug-in for yum that allows users to specify which package types within a package group should be installed when using yum groupinstall.

Enable GNOME

Since the server was previously running on CLI mode, we need to change the initialization process for the machine to boot up in GUI mode.

Open /etc/inittab using a text editor and change following line:

After making the change, reboot the machine.

# init 6
Note that you can switch from GUI to CLI mode manually by using following method:

GUI to CLI: Ctrl + Alt + F6
CLI to GUI: Ctrl + Alt + F1

Installing Additional Applications
After logging in to the GNOME Desktop, you can now go to System > Administration > Add/Remove Software to manage application in CentOS.

After installing gnome packages .Issue the below command to install VNC package along with dependencies

yum -y install tigervnc-server pixman pixman-devel libXfont
Create user name and password.
[ ~]# adduser user1
[ ~]# adduser user2
[ ~]# passwd user1
[ ~]# passwd user2

Create VNC passwords for the Users created.
[ ~]# su – user1
[ ~]$ vncpasswd
[ ~]$ logout
[ ~]# su – user2
[ ~]$ vncpasswd
[ ~]$ logout

Now open /etc/sysconfig/vncservers file and add the following lines at the end of the file( Edit as per your usernames ).
VNCSERVERS=”1:user1 2:user2″
VNCSERVERARGS[1]=”-geometry 1024×768″
VNCSERVERARGS[2]=”-geometry 800×600″

Here we have configured session 1 with 640×480 resolution for the user “user1” and session 2 with 800×600 resolution for the user “user2”.
Start vnc service
[ ~]# service vncserver start

and issue this command to start vnc service automatically during startup.
[ ~]# chkconfig –levels 235 vncsever on

Now in remote machine, start vncviewer type the IP and session as below to view their respective sessions. for user1 for user2

[ ~]# netstat -anlp|grep vnc
tcp 0 0* LISTEN 1374/Xvnc

vnc server
vnc server

» Check the iptables in the server, if you are not able to connect the sessions.
Issue the below command to stop iptables service.
[ ~]# service iptables stop

try again.
» you might receive the below error while starting the vnc service.
/usr/bin/Xvnc: symbol lookup error: /usr/bin/Xvnc: undefined symbol: pixman_composite_trapezoids
/usr/bin/Xvnc: symbol lookup error: /usr/bin/Xvnc: undefined symbol: pixman_composite_trapezoids


Issue the below command to install pixman,pixman-devel and libXfont packages.
[ ~]# yum -y pixman pixman-devel libXfont

This command will update everything .
[ ~]# yum update

and restart the VNC service and try again.