How to Setup VNCServer on CentOS 7 for Remote Access

VNCServer helps connect to a host remotely, the clients see a graphical interface (typically the desktop manager like GNOME or XFCE or KDE). The following steps can be followed to configure VNCServer on CentOS 7 (and also RHEL7.x).

• Install the X Window system (if not already there):
  
  First make sure that yum is configured. You may run the following commands (as root) view and install the X Windows System (GNOME).
  
  ~]# yum group list
Installed Environment Groups:
    Server with GUI
Available Environment Groups:
    Minimal Install
    Infrastructure Server
    File and Print Server
    Basic Web Server
    Virtualization Host
Available Groups:
    Compatibility Libraries
    Console Internet Tools
    Development Tools
    Graphical Administration Tools
    Legacy UNIX Compatibility
    Scientific Support
    Security Tools
    Smart Card Support
    System Administration Tools
    System Management
Done

~]# yum groupinstall "Server with GUI"
  


• Install VNCServer:
  
  Install the tigervnc-server package, which provides the required VNCServer functionality.
  
  ~]# yum install tigervnc-server*
  


• Setup VNCServer user and Firewall:
  
  The VNCServer runs at ports starting from 5900 and port identifies a display number. For instance port 5901 indicates VNCServer display :1 which can typically be accessed via hostname/ipaddress:1. If needed these ports should be added to the firewall as well.
  
  Create a user test which will be used to login from the VNC client.
  
  ~]# useradd testuser
~]# passwd testuser
  
  Login as testuser and set a password for VNCServer.
  
  ~]# su - testuser
~]$ vncpasswd
~]$ logout
~]#
  
  Let us assume that we will be hosting VNCServer at display :1 (port 5901). Add this port to the firewall.
  
  ~]# firewall-cmd --permanent --zone=public --add-port=5901/tcp
~]# firewall-cmd --reload
  


• Configure VNCServer at display :1 (port 5901):
  
  Copy the template service file that came with the VNCServer package to /etc/systemd/system/. Rename the file to indicate display :1.
  
  ~]# cp /lib/systemd/system/vncserver@.service /etc/systemd/system/vncserver@:1.service
  
  Edit the file with an editor (vim or emacs) and change the <USER> to the testuser we have created above.
  
  [Unit]
Description=Remote desktop service (VNC)
After=syslog.target network.target

[Service]
Type=forking
# Clean any existing files in /tmp/.X11-unix environment
ExecStartPre=/bin/sh -c '/usr/bin/vncserver -kill %i > /dev/null 2>&1 || :'
ExecStart=/usr/sbin/runuser -l <USER> -c "/usr/bin/vncserver %i"
PIDFile=/home/<USER>/.vnc/%H%i.pid
ExecStop=/bin/sh -c '/usr/bin/vncserver -kill %i > /dev/null 2>&1 || :'

[Install]
WantedBy=multi-user.target

  Save the changes made to the file. Now enable the service to run at boot and start the service.
  
  ~]# systemctl daemon-reload
~]# systemctl enable vncserver@:1.service
~]# systemctl start vncserver@:1.service
  

Now use a VNC Client software to connect to the VNCServer running on the host at <hostname>:1.

That's it!