[K12OSN] tight vnc connection to ltsp client refused (111 error)

Eric Harrison eharrison at mail.mesd.k12.or.us
Fri May 19 22:53:24 UTC 2006

Robert Arkiletian wrote:
> On 5/19/06, Trond Mæhlum <trond at maehlum.net> wrote:
>> Robert Arkiletian skrev:
>> > On 5/17/06, Dan Visentin <visentind at hdsb.ca> wrote:
>> >>
>> >>  Howdy Folks,
>> >>
>> >>  I've been experimenting with Fl_TeacherTool (brilliant Rob!) but
>> cannot
>> >> monitor the LTSP clients.  I cannot even use the vncviewer to view
>> >> clients.
>> >> In all cases I get a "connection refused (111)" error.  I've run
>> >> vncpasswd
>> >> and copied files etc. as per instructions but to no avail.
>> >>
>> >
>> > What version of k12ltsp are you using? k12ltsp 5.0 does not work with
>> > the monitor/control feature of fl_TT because there is no vnc X
>> > extension module compiled in the LBE. I developed fl_TT using k12ltsp
>> > 4.2.1EL. Although NO version of k12ltsp has the required module
>> > compiled in the LBE, out of sheer luck the required files when copied
>> > from the host OS seem to work in 4.2.1EL. That's why I labeled them
>> > experimental.
>> Robert and Dan,
>> This also works on K12LTSP 4.4.x. It seems that it will work on all
>> installations of LTSP4.1 that I have tried. Sadly, it does not work on
>> LTSP4.2 for now. I am one of many (I think) that will not let go of this
>> feature.
>> I have tried it on the new Ubuntu and Skolelinux ltsp as well. I would
>> suspect it to be much easier when you can chroot into the ltsp-tree and
>> apt-get install vnc4server. Sadly I haven't been able to get it working
>> there either. There's too many changes in ltsp, so the how-to doesn't
>> apply to get the vncserver started at login on the terminal.
> Hopefully Eric or Jim will provide an rpm to add the necessary
> libraries to the LBE, if enough people request it.
> Fl_TT is useful for more than just teachers. Perhaps Jim will decide
> to add it to LTSP as it does provide a solution for some of the
> desired future functionality of LTSP's roadmap. eg broadcasting,
> shadowing, etc

I managed to build a working binary. Still much work to do in order to
package it up & provide patches for Jim & the LTSP crew.

But for those of you who want to test it out, here is the
quick-and-dirty instructions:


4.  Optional: Step 4 is only required to enable the experimental support
        to Monitor and Control.

        Edit the file /opt/ltsp/i386/etc/lts.conf
        Fine the line X4_MODULE_01=glx and change it to:

        X4_MODULE_01 = vnc

        Then edit the file /opt/ltsp/i386/etc/build_x4_cfg
        and add the following between (Secton "Screen") and
        (EndSubSection), so it looks
        like this:

     Section "Screen"
          Identifier "Screen0"
          Device "My Video Card"
          Monitor "My Monitor"
          DefaultDepth  ${X_COLOR_DEPTH:-16}
          Subsection "Display"
                  Depth ${X_COLOR_DEPTH:-16}
                  Modes ${MODE[*]}
     # Added to enable Monitor/Control in Fl_TeacherTool
                   Option "httpdir" "/usr/share/vnc/classes"
                  Option "PasswordFile" "/root/.vnc/passwd"
                  Option "rfbport" "5900"
                  Option "usevnc"

    Now you'll have to make a password for the vnc-session. Run this
    command as root:


    Choose a password and copy the password file into the ltsp-tree

    #cp -R -p /root/.vnc /opt/ltsp/i386/root/

    Now you must copy the vnc-module into the ltsp-tree:

    # cd /opt/ltsp/i386/usr/X11R6/lib/modules/extensions/
    # wget ftp://k12linux.mesd.k12.or.us/pub/vnc-for-ltsp42/vnc.so

    Reboot the clients and the new Monitor/Control buttons in
    Fl_TeacherTool should work.

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