X11 virtual frame buffer

# Xvfb :99 -screen 0 1600x900x16 -nolisten tcp 2>&1 >/dev/null &

This will start a new X virtual frame buffer at display :99 on screen 0 .

We can connect vnc to this vfb, using x11vnc.

First add Extra Packages for Enterprise Linux repo rpm
# yum install  https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

Then install x11vnc
#yum install x11vnc

start the x11vnc
#x11vnc -display :99

Now you can connect vnc to the default port 5900