VNC Server in Ubuntu 16.04, 18.04 and CentOS 7

If you work with a server hosted in the cloud environment, most of the time, you may find it very useful to have graphical access to the server. Here, we will install TightVNC on the Ubuntu 16.04 and CentOS 7 and VNC4Server on Ubuntu 18.04 and then connect to it. In order to access the operating system graphically, a graphical environment should be installed on the OS. The most used ones are LXDE (fig 1), Mate (fig 2), Xfce (fig 3), KDE (fig 4) and Gnome (fig 5). Running each one requires different hardware specifications.

Fig 1: LXDE Plasma Environment

Fig 2: Mate Environment

Fig 3: XFCE Environment

Fig 4: KDE Plasma Environment

Fig 5: Gnome Environment

Getting Started

If the operating system has a graphical environment you may skip the Install Graphical Environment section. Let’s start with CentOS 7:

CentOS 7

Install Graphical Environment

To install Gnome on CentOS 7:

sudo yum groupinstall "GNOME Desktop"

TightVNC Server Installation and Configuration

TightVNC server is a popular VNC server. Install it on the CentOS by:

sudo yum install tigervnc-server xorg-x11-fonts-Type1

VNC Server Configuration

The next step is to create a config file for VNC server. In CentOS, we can copy the default config file and modify it to reflects the appropriate configuration.

sudo cp /lib/systemd/system/vncserver@.service /etc/systemd/system/vncserver@:1.service

The number 1 in vncserver@:1.service shows the display port in VNC server. The VNC server uses ports ranging from 5901 to 5909. Copy the bellow configuration to the newly created file and replace the centos with your username.

[Unit]
Description=Remote desktop service (VNC)
After=syslog.target network.target

[Service]
Type=forking
ExecStartPre=/bin/sh -c '/usr/bin/vncserver -kill %i > /dev/null 2>&1 || :'
ExecStart=/usr/sbin/runuser -l centos -c "/usr/bin/vncserver %i"
ExecStop=/bin/sh -c '/usr/bin/vncserver -kill %i > /dev/null 2>&1 || :'

[Install]
WantedBy=multi-user.target

We realized a line like this “PIDFile=/home//.vnc/%H%i.pid" in the configuration file may cause problem in starting the service. So we have removed it. Then, reload the configuration and enable the service to start on boot:

systemctl daemon-reload
systemctl enable vncserver@:1.service

Running the VNC Service

Now run the VNC server. If this is the first time then you have to provide the password for VNC server. This password will be used when you connect to the VNC sever.

vncserver

After running VNC server, kill the session that the previous command just created and run the service:

vncserver -kill :1
sudo systemctl start vncserver@:1.service

Ubuntu 16.04 and 18.04

Install Graphical Environment

I prefer to install the graphical environment using a tool called tasksel. It used to install a collection of tools:

To install Ubuntu Mate:

sudo apt install tasksel
sudo tasksel

When you run the tool, you will see a user interface which let you install collections of tools, including a couple of graphical environment for Ubuntu. In this dialog let’s select Ubuntu Mate minimal installation:

VNC Server Installation and Configuration Ubuntu 16.04

Install TightVNC server on the Ubuntu by:

sudo apt install tightvncserver

VNC Server Configuration

In Ubuntu we have to create a file named as vncserver@.service:

sudo vim /etc/systemd/system/vncserver@.service

Put the content bellow into the file. Do not forget to replace every ubuntu word with your account username on the machine:

[[Unit]
Description=Start TightVNC server at startup
After=syslog.target network.target

[Service]
Type=forking
User=ubuntu
Group=ubuntu
WorkingDirectory=/home/ubuntu

PIDFile=/home/ubuntu/.vnc/%H:%i.pid                                                                                          
ExecStartPre=-/usr/bin/vncserver -kill :%i > /dev/null 2>&1
ExecStart=/usr/bin/vncserver :%i
ExecStop=/usr/bin/vncserver -kill :%i

[Install]
WantedBy=multi-user.target

sudo systemctl daemon-reload
sudo systemctl enable vncserver@1

Running the VNC Service

Now we need to run the VNC server and If this is the first time then you have to provide the password for VNC server:

vncserver

After running VNC server, kill the session that the previous command just created and run the service:

vncserver -kill :1
sudo systemctl start vncserver@1

VNC Server Installation and Configuration Ubuntu 18.04

Install VNC4Server on the Ubuntu by:

sudo apt install vnc4server -y

VNC Server Configuration

Configuration of vnc4server is quite easy. Run the vncserver for the first time to set the password:

vncserver

It is just enough to have the file ~/.vnc/xstartup with following configuration and no change is neccessary:

#!/bin/sh                                                                                                                                               
xrdb $HOME/.Xresources
xsetroot -solid grey
#x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#x-window-manager &
# Fix to make GNOME work
export XKL_XMODMAP_DISABLE=1
/etc/X11/Xsession

Running the VNC Service

Now we run the VNC server:

vncserver

After running VNC server, kill the session that the previous command just created and run the service:

vncserver -kill :1
SCREEN_SIZE=1440x900
vncserver -geometry $SCREEN_SIZE :1

Access to the Remote Machine using VNC Client

There are a couple of VNC viewer client avaialbe. Download one of them and connect to server:

vnc://IP_address:5901

Troubleshooting

When you try to install a graphical environment and start the VNC server, it is pretty common to encounter errors and gray screen. Here is a list of resources which may be useful:

• The gray screen in VNC viewer when using Gnome in Ubuntu
• “Unable to connect to host: No route to host” Allow traffic to pass through Iptables in CentOS
• Differrent graphical environments for Linux
• A Good article to install VNC server from begging to the end on CentOS