Configure VNC Server on CentOS 7 / RHEL 7

Let’s start. If you don’t have desktop environment ( X windows ), issue the below commands one by one to install. It will take few minutes to install packages.

[root@world ~]# yum check-update

[root@world ~]# yum groupinstall "X Window System"

[root@world ~]# yum install gnome-classic-session gnome-terminal nautilus-open-terminal control-center liberation-mono-fonts

[root@world ~]# unlink /etc/systemd/system/default.target

[root@world ~]# ln -sf /lib/systemd/system/graphical.target /etc/systemd/system/default.target

[root@world ~]# reboot

After reboot, you will get Centos 7 desktop .

[root@server ~]# yum groupinstall "GNOME Desktop" "Graphical Administration Tools"

                                        ----X----

# yum -y install tigervnc-server xorg-x11-fonts-Type1 xinetd xrdp

# yum install tigervnc-server xorg-x11-fonts-Type1 -y

                              IF Problem 

# yum -y install xrdp --enablerepo=cr

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

 # vi /etc/systemd/system/vncserver@:1.service

At the end of the file, you will find the lines like below.

Now open /etc/systemd/system/vncserver@:1.service file and replace with your username .

                                   ---------------------------------------------------------

                                       ---------------------------------------------------------

Find these lines:

Line Edit ---------------

40    ExecStart=/sbin/runuser -l root -c "/usr/bin/vncserver %i"

41    PIDFile=/root/.vnc/%H%i.pid

-----OR-------

[Unit]

Description=Remote desktop service (VNC)

After=syslog.target network.target

[Service]

Type=simple

# 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 root -c "/usr/bin/vncserver %i"

PIDFile=/home/root/.vnc/%H%i.pid

ExecStop=/bin/sh -c '/usr/bin/vncserver -kill %i > /dev/null 2>&1 || :'

[Install]

WantedBy=multi-user.target

# systemctl daemon-reload

# vncpasswd

#  c

systemctl enable vncserver@:1.service

systemctl start vncserver@:1.service

systemctl restart vncserver@:1.service

 systemctl start xrdp.service

 systemctl enable xrdp.service

 systemctl start vncserver@:display_number.service

 systemctl enable vncserver@:display_number.service

Firewall settings:

# firewall-cmd --permanent --zone=public --add-service vnc-server

# firewall-cmd --reload

# systemctl restart firewalld.service

Additional Commands :

» To stop VNC service .

[root@world ~]# systemctl stop vncserver@:1.service

» To disable VNC service from startup ( permanent ).

[root@world ~]# systemctl disable vncserver@:1.service

» To stop firewall ( For troubleshooting ).

[root@world ~]# systemctl stop firewalld.service

 systemctl daemon-reload

 systemctl start vncserver@:1

 systemctl status vncserver@:1

 systemctl enable vncserver@:1

In order to list the opened ports that are in the listening state, run the ss command as below.

# ss -tulpn| grep vnc

Then to allow external VNC clients to connect to the VNC server in CentOS, ensure that the proper VNC open ports are allowed to pass through your firewall.

# firewall-cmd --add-port=5901/tcp

# firewall-cmd --add-port=5901/tcp --permanent

Connecting to CentOS Desktop via VNC Client

#  yum -y install vinagre

#  ss -tlpn| grep Xvnc

3. Now, remotely connect to CentOS Desktop using this new VNC session, supply the IP: port combination (192.168.1.23:5903) in VNC client

Then to stop the VNC server instances, run the below command.

# killall Xvnc

# vncserver -kill :1 

-------------Config VNC  --------------

Install the tigervnc server, X11 fonts and xinetd.

Enable the XDMCP.

Add the following content.

Create Xinetd service.

Place the following content on the above file.

Create VNC service.

Add the following line at the end of file.

Restart xinetd service

Add firewall rules to allow the VNC connection, the following rule is set as per the port-offset mentioned in the previous step.

Reboot the machine, if required.

Use VNC viewer to connect.

###################################################################################

------------XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX____________XXXXXXXXXXXXXXXXXXXXXXXX______________________

CentOS 7.4

[srijan@world ~]$ 

 Configuring Your Firewall

Next, we will need to configure the firewall to allow VNC traffic through ports 5904 and 5905 only. CentOS 7 uses Dynamic Firewall through the firewalld daemon; the service doesn't need to restart for changes to take effect.

The firewalld service should start automatically at system boot time, but it's always good to check:

# firewall-cmd --state

This should show:

running

If the state is "not running" for any reason, execute the following command to make sure it's running:

# systemctl start firewalld

Now add the rules for ports 5904 and 5905:

# firewall-cmd --permanent --zone=public --add-port=5904-5905/tcp

OR

# firewall-cmd --permanent --zone=public --add-port=5905/tcp

Output:

success

Reload the firewall:

# firewall-cmd --reload

Output:

success

-----------------------ERROR

VNC won't start CentOS 7

# rm -f /tmp/.X4-lock 

# rm -f /tmp/.X11-unix/X4

This worked for me on Centos7:

$ rm /tmp/.X11-unix/*

# systemctl restart vncserver@:1.service

Automatic (recommended):

Install EPEL and nux Desktop repository rpms.

Manual:

Create a repository file.

Place the following content. Once added, save and close the file.

---------------------------------------------

As a temporary fix you could delete them:

rm -i /tmp/.X11-unix/X4

rm /tmp/Xn

rm -rf /tmp/.X11-unix/Xn (where n is the port/socket number)

For a more permanent solution, you can add this line under the "ExecStartPre" line:

ExecStartPre=/bin/sh -c 'rm -rf /tmp/.X11-unix/X* > /dev/null 2>&1 || :'

After doing either of these steps, you should either (re)start the vnc daemon or reboot.

------------------------------

# vncserver -kill :1

# vncserver -kill :#

# vi ~/.vnc/xstartup

# Uncomment the following two lines for normal desktop: unset SESSION_MANAGER exec /etc/X11/xinit/xinitrc

----------OR-------

####### Content of home/USERNAME/.vnc/xstartup, owned by USERNAME #!/bin/sh unset SESSION_MANAGER unset DBUS_SESSION_BUS_ADDRESS

exec /etc/X11/xinit/xinitrc &

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