Saturday, February 18, 2012

How to set up remote logins via VNC for Debian, Solaris and Red Hat Clients

Debian Linux (6)


       1. Run the following commands respectively.

root# apt-get update

root# apt-get upgrade

root# apt-get dist-upgrade


       2. Reboot the OS.

root# reboot


       3. Install the GNOME desktop.

root# apt-get install gnome-desktop-environment

**  if "apt-get install gnome-desktop-environment" says the packages are missing ensure "deb http://ftp.us.debian.org/debian squeeze main contrib non-free" is added to the sources.list file.


 **********adding the link to sources.list************************************************************************

                         I.  root# vi /etc/apt/sources.list

                       II.  Paste "deb http://ftp.us.debian.org/debian squeeze main contrib non-free" without quotes.

                      III.  Restart the process from step 1.

 ******************************************************************************************************************


            4. Install some (required) fonts for the VNC server GNOME session.

  root# apt-get install xfonts-100dpi
  root# apt-get install xfonts-100dpi-transcoded
  root# apt-get install xfonts-75dpi
  root# apt-get install xfonts-75dpi-transcoded
       root# apt-get install xfonts-base


       5. Install VNC.

                     root# apt-get install vnc4server


       6. Run VNCserver manually and set up a password.

   root# vncserver


       7. Making VNCserver start at system start up. 

*        Run the following command to create the vncserver file.

root# vi /etc/init.d/vncserver


*        Copy the following script, paste and save.


 8. Replace “my-vnc-server” with the hostname and keep with quotes. (Optional)


#-----Beginning of the script----------------------------------------------------------------------------------------

#!/bin/sh -e
### BEGIN INIT INFO
# Provides:          vncserver
# Required-Start:    networking
# Required-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
### END INIT INFO

PATH="$PATH:/usr/X11R6/bin/"

# The Username:Group that will run VNC
export USER="root"
#${RUNAS}

# The display that VNC will use
DISPLAY="0"

# Color depth (between 8 and 32)
DEPTH="16"

# The Desktop geometry to use.
#GEOMETRY="<WIDTH>x<HEIGHT>"
GEOMETRY="800x600"
#GEOMETRY="1024x768"
#GEOMETRY="1280x1024"

# The name that the VNC Desktop will have.
NAME="my-vnc-server"

OPTIONS="-name ${NAME} -depth ${DEPTH} -geometry ${GEOMETRY} :${DISPLAY}"

. /lib/lsb/init-functions

case "$1" in
start)
log_action_begin_msg "Starting vncserver for user '${USER}' on localhost:${DISPLAY}"
su ${USER} -c "/usr/bin/vncserver ${OPTIONS}"
;;

stop)
log_action_begin_msg "Stopping vncserver for user '${USER}' on localhost:${DISPLAY}"
su ${USER} -c "/usr/bin/vncserver -kill :${DISPLAY}"
;;

restart)
$0 stop
$0 start
;;
esac

exit 0

#-----End of the script-----------------------------------------------------------------------------------------------


       9. Grant permissions for everyone to execute the file.

     root# chmod +x /etc/init.d/vncserver


      10. Register the VNCServer service to run at startup.

     root# update-rc.d vncserver defaults


******************************************************************************************************************
     
       *  If VNC login shows a gray screen

     root# chmod 755 /etc/X11/xinit/xinitrc



Solaris (10)

1. Download the latest VNC package for Solaris from http://www.realvnc.com/products/download.html


       2. Go to the download location of the file in the terminal and run the following commands.

root# gunzip vnc-4_1_3-sparc_solaris.pkg.gz

root# pkgadd –d vnc-4_1_3-sparc_solaris.pkg

   Solaris 10 is shipped with a basic VNC service mostly configured. This is the procedure to enable it.


       3. Find VNC service.

root# svcs -a | grep -i vnc
disabled 13:47:12 svc:/application/x11/xvnc-inetd:default 


       4. Enable VNC service.

root# svcadm enable svc:/application/x11/xvnc-inetd:default 


       5. Note that VNC is broken by default, some changes will be required.

root# svcs svc:/application/x11/xvnc-inetd:default
STATE STIME FMRI
maintenance 14:22:41 svc:/application/x11/xvnc-inetd:default


      6. Append VNC to the /etc/services.

root# echo "vnc-root\t5900/tcp\t\t\t# Xvnc" >>/etc/services


       7. Check /etc/services.

root# tail /etc/services
...
snmpd 161/udp snmp # SMA snmp daemon
vnc-root 5900/tcp # Xvnc


        8. Note, the GNU display manager is not customized yet, and needs correction.

root# ls -al /etc/X11/gdm/custom.conf
/etc/X11/gdm/custom.conf: No such file or directory


        9. Enable and configure GNU display manager for VNC.

root# cat >/etc/X11/gdm/custom.conf <<!
[xdmcp]
Enable=true
[security]
DisallowTCP=false
AllowRoot=true
AllowRemoteRoot=true
!


       10. Check the customization configuration file.

root# ls -al /etc/X11/gdm/custom.conf
-rw-r--r-- 1 root root 85 Dec 19 14:43 /etc/X11/gdm/custom.conf


       11. Disable and re-enable, and validate the VNC service.

root# svcadm disable svc:/application/x11/xvnc-inetd:default
STATE STIME FMRI
disabled 14:46:29 svc:/application/x11/xvnc-inetd:default

root# svcadm enable svc:/application/x11/xvnc-inetd:default

root# svcs svc:/application/x11/xvnc-inetd:default
STATE STIME FMRI
online 14:46:43 svc:/application/x11/xvnc-inetd:default 


       12. Edit /etc/default/login and comment out the following line. 
             (This permits to log on as Root.)

                     * Force-save using wq! as it is read-only.

                             # CONSOLE=/dev/console


            
RHEL (Red Hat Enterprise Linux) 

If the RHEL installation is licensed then this is not difficult at all. You just need to run

# yum install tigervnc-server -y

at a terminal. However this gets complicated when the installation of RHEL is not licensed.

After a considerable number of disappointing hours of searching, testing, and some research I finally found a solution to this. Here I am going to use TigerVNC as the VNC server and RealVNC viewer as the client (you can use any VNC viewer you prefer).

1. Navigate to the TigerVNC downloads which at the moment of this blog post is hosted as a SourceForge project here  and download the latest build corresponding to the bit version of your linux installation.

2. Extract the contents into a suitable location.

3. Within the extracted contents a folder named bin exists and it contains all the binaries required for the sound operation of VNC server (except the one which as they say is obsolete now). Locate this folder and copy the contents of it to /bin directory in linux. The following files need to be copied.
  • vncconfig
  • vncpasswd
  • vncserver
  • Xvnc

4. Execute the command vncsever at a terminal.

# vncserver

  • This will require you to set a password for logging in via VNC remotely.
  • This will also create the necessary files required to start a xsession for a particular user when logging in via VNC.
5. Usually after the above step you are good to go but in some cases you might end up with an error Connection timed out(1006) at the VNC viewer when you try to log in. This is because the host in which the VNC server runs is blocking the VNC communication, i.e. it's blocking the VNC port-5900. Here you have to allow the port 5900 at the firewall as a trusted port or if security is not a big issue with the Red Hat host then you can simply disable it.

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