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people:priestdo:tips:vnc_inetd_gdm [2009/09/11 14:31] (current)
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 +====== VNC over inetd with gdm - number of session limitation ======
 +
 +There are a lot of pages about setting up vnc over inetd.  I had been running such a setup for years with 10 - 20 simultaneous sessions being commonplace,​ but an upgrade of the server to ubuntu 9.4 broke my configuration.  Eventually all but one problem had been worked out by poking around the changelogs, reading a few man pages and using the standard net searches.  That problem was that only 2 simultaneous sessions were supported.  The fix was in the gdm configuration.  Here are a few more details to see if your problem is from the same cause.
 +
 +  - vnc over inetd is working for 2 sessions (gdm login screen comes up)
 +  - any more than 2 sessions and those additional sessions never launch even a gray screen (before gdm login).
 +  - messages like "end of stream"​ or "​connection refused"​ may be seen depending on how you launch your viewer.
 +  - if you kill one of the 2 working sessions, another session (independent of machine location) will become available in about 20 seconds.
 +  - tests or debugging will show that inetd is launching Xvnc but that is terminating.
 + 
 +The above told me that there was a limit imposed someware on the total number of sessions and it wasn't inetd'​s fault.
 +The fact that the limit was independent of the sessions being local (tunneled over ssh) or from a vnc terminal on the local network and that no matter were it came from I could get 2 sessions going before it would stop got me out of looking at /​etc/​hosts.allow or similar places for a solution. ​
 +
 +The thing that fixed it was adding a "​DisplaysPerHost=XX"​ line to the /​etc/​gdm/​gdm.conf-custom file in the [xdmcp] section were "​XX"​ is the number of sessions you want to support.  So if you wanted to support 16 simultaneous vnc sessions it would look something like this:
 +<​code>​
 +[xdmcp]                                                                         
 +Enable=true                                                                     
 +                                                                                
 +HonorIndirect=false                                                             
 +                                                                                
 +DisplaysPerHost=16                                                              
 +</​code>​                   
 +
 +If you use the graphical setup tool gdmsetup (/​usr/​sbin/​gdmsetup) you get on the ``Remote`` tab, ``Configure XDMCP`` button.  There you will see the option "​Displays per host"​  //that// is what you need to change.  Even though it looks like you would want "​Maximum remote sessions"​.  Remember, these are vnc sessions, so as far as gdm knows they are all on the local host.
 +
 +Anyway, that is what solved my problem.  Hope this helps.
 +
 +-Greg
 + --- //​[[priestdo@cs.vassar.edu|Greg Priest-Dorman]] 2009/09/11 14:12//