Configuring VNC Server on Linux

• init (Original Method)
• systemd (New Method)
• VNC Clients

Firewall

Open port OEL 7 :

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

 

systemd

Install the VNC Server.

# yum install tigervnc-server

Create a new configuration file for each of the display numbers you want to enable. In the following case, I am setting up the display number “:3”. Notice how the display number is included in the configuration file name.

# cp /lib/systemd/system/vncserver@.service /lib/systemd/system/vncserver@:3.service

Edit the new configuration file, amending the user and startup arguments as necessary. An example of the changed lines is shown below. All other lines should be unmodified.

User=oracle
ExecStart=/usr/bin/vncserver %i -geometry 1280x1024

 The vncserver service unit file
#
# Quick HowTo:
# 1. Copy this file to /etc/systemd/system/vncserver@:.service
# 2. Edit root and vncserver parameters appropriately
#   ("runuser -l root -c /usr/bin/vncserver %i -arg1 -arg2")
# 3. Run `systemctl daemon-reload`
# 4. Run `systemctl enable vncserver@:.service`
#
# DO NOT RUN THIS SERVICE if your local area network is
# untrusted!  For a secure way of using VNC, you should
# limit connections to the local host and then tunnel from
# the machine you want to view VNC on (host A) to the machine
# whose VNC output you want to view (host B)
#
# [user@hostA ~]$ ssh -v -C -L 590N:localhost:590M hostB
#
# this will open a connection on port 590N of your hostA to hostB's port 590M
# (in fact, it ssh-connects to hostB and then connects to localhost (on hostB).
# See the ssh man page for details on port forwarding)
#
# You can then point a VNC client on hostA at vncdisplay N of localhost and with
# the help of ssh, you end up seeing what hostB makes available on port 590M
#
# Use "-nolisten tcp" to prevent X connections to your VNC server via TCP.
#
# Use "-localhost" to prevent remote VNC clients connecting except when
# doing so through a secure tunnel.  See the "-via" option in the
# `man vncviewer' manual page.


[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=/sbin/runuser -l username  -c "/usr/bin/vncserver %i -geometry 1280x1024"
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

Run the following command.

# systemctl daemon-reload

Set the VNC password for the user defined in the new configuration file.

# su - oracle
$ vncpasswd
Password:
Verify:
$ exit
logout
#

Enable the service for autostart and start the service.

# systemctl enable vncserver@:3.service
# systemctl start vncserver@:3.service

You should now be able to use a VNC viewer to connect to system using the display number and password defined.

Use the following commands to stop the service and disable autostart.

# systemctl stop vncserver@:3.service
# systemctl disable vncserver@:3.service

VNC Clients

Once your VNC server is configured, you can connect to it from any VNC server. On Linux this will often be TigerVNC, installed using the following command.

# yum install tigervnc

Connect to a VNC server using the following command.

# vncviewer machine-name:port

# vncviewer maggie.localdomain:3
# vncviewer 192.168.0.4:3

Fedora 18  gets an “Oh no. Something has gone wrong” message in the VNC Client when trying to connect.

This is bug 896648 in the Red Hat bugzilla. According to comment 15 you can fix it by:

• Add -session optional pam_systemd.so to /etc/pam.d/runuser-l; the whole file should look like:

  auth            include         runuser
  session         optional        pam_keyinit.so force revoke
  -session        optional        pam_systemd.so
  session         include         runuser
  

• Edit vncserver@:<display>.service
  • Change Type to simple
  • Add an -fg parameter to the vncserver command in ExecStart
  • Comment out the ExecStop line