How to restrict per user vnc sessions count ?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 7
  • TigerVnc

Issue

  • Restrict user's to use only one or a specific count of VNC sessions.
  • Multiple VNC sessions affect the systems performance.

Resolution

DISCLAIMER: The following information has been provided by Red Hat, but is outside the scope of the posted Service Level Agreements and support coverage. Such changes are unsupported and have not been gone through extensive testing. You would need to test and confirm in your environment. Also note that tigervnc-server package update would replace the changes.
The information is provided as-is and any configuration settings or installed applications made from the information in this article could make the Operating System unsupported by Red Hat Global Support Services. The intent of this article is to provide information to accomplish the system's needs. Use of the information in this article at your own risk.
  • Xvnc does not have executables which could restrict the number of VNC sessions accessible per user.
  • Hence, to get the Xvnc to restrict the number of VNC sessions a simple tweak is to be performed to 'usr/bin/vncserver'.
  • To accomplish this write a perl script by adding a subroutine check for active vnc sessions for the user and restrict it to 1 or as desired.
  • Below is the script to restrict the VNC sessions per user :
$ vi /usr/bin/vncserver

301 # Now start the X VNC Server
302 
303 # Maximum session limit to 1 per user.
304 &vnclimit();
305 


890     }
891 }
892 
893 sub vnclimit {
894 $countoutput = `ps -u $ENV{USER} | grep -i Xvnc | wc -l`;
895 if ($countoutput >= 1) {
896         print "You are already running a VNC session for $ENV{USER} user. Maximum session is limited to 1 per user!\n";
897         print "Run 'vncserver -list' to list the current session\n\n";
898         print "Please contact your System Administrator for more details.\n";
899         exit;
900         }
901 }

EXAMPLE

$ vncserver 
You are already running a VNC session for deepu user. Maximum session is limited to 1 per user!
Run 'vncserver -list' to list the current session

Please contact your System Administrator for more details.

$ vncserver -list

TigerVNC server sessions:

X DISPLAY # PROCESS ID
:3      32621
  • Component
  • vnc

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