LTSP notes

These are my personal notes wrt LTSP installations, tips and tricks that I have needed in various setups.  Instead of just storing these in my own notebook, I share them here for the benefit of anyone that may benefit from them.  Feel free to leave comments, corrections or suggestions.

Ubuntu 12.04 64bit Server with LTSP

i386 Clients that don’t support required ‘cmov’

Norhtec Surfboards with XCore86 processors:

  1. The last version of Ubuntu that has the ‘cmov’ instruction built into the kernel is 10.04.  I suppose it is possible to compile a custom kernel with ‘cmov’ support, but I think Ubuntu has removed code from their source, so one would need quite a bit of customisation to overcome this.  Not for me, I’ve wasted too much time on things I don’t really know enough about.
  2. Debian continues supporting ‘cmov’ up to the latest build.
  3. Debian LTSP implements NFS to connect from the chroot booted system to the server, Ubuntu uses NBD.
  4. With Ubuntu 10.04 Lucid, the NBD server listened on a port, typically 2000, 2001, 2002, etc.  Since 12.04 Precise (or maybe even the release before that?), the chroot booted clients connects with a named pipe instead of a port.
  5. To allow a 10.04 chroot client to connect to the 12.04 server, do the following
      1. $ sudo ltsp-chroot -a i386
        $ vim /etc/ltsp/update-kernels.conf

        Change the content to:
        BOOTPROMPT_OPTS=”append ro initrd=initrd.img quiet splash nbdport=2002″
        NBD_ROOT_NAME=ltsp_i386


        Now run:

        $ /usr/share/ltsp/update-kernels
        $ exit


        $ sudo ltsp-update-kernels

        Now the file /var/lib/tftpboot/ltsp/i386/pxelinux.cfg/default should reflect the changed connection method using a port.


      2. Change the nbd-server config as follows:
        $ sudo vim /etc/nbd-server/config
        [generic]
        user = nbd
        group = nbd
        includedir = /etc/nbd-server/conf.d
        oldstyle = true


        $ sudo vim /etc/nbd-server/conf.d/ltsp_i386.conf
        [/opt/ltsp/i386]
        exportname = /opt/ltsp/images/i386.img
        port=2002
        readonly = true


        $ sudo vim /etc/nbd-server/conf.d/swap.conf
        [swap]
        port = 2002
        exportname = /tmp/nbd-swap/%s
        prerun = nbdswapd %s
        postrun = rm -f %


      3. A different way (which I only found out yesterday by going through the script), is:
        $ sudo ltsp-update-image -a i386 -o “quiet splash nbdport=2002”

     

Extra notes:

There is a file /etc/ltsp/ltsp-update-image.excludes which removes certain file from the chroot when the image is created.  Edit this to allow sshd keys, home directories and more to included in the image.

If the client doesn’t log in to the server due to ssh keys not in the ssh_known_hosts file, delete the /etc/ssh/ssh_known_hosts file in the chroot, run ltsp-update-sshkeys and then ltsp-update-image.

If the screen resolution notification pops up after logon, delete the users ~/.config/monitors.xml file.

To enable sshd on the thin client:
In /etc/ltsp/ltsp-update-image.excludes comment out:
# etc/ssh/ssh_host_*_key

In /var/lib/tftpboot/ltsp/i386/lts.conf add:
KEEP_SYSTEM_SERVICES=”ssh”

Printers connected to the thin client?
check the device the printer is on: ls -la /dev/usb/lp1 for example  (on wheezy)
then set lts.conf to:
LOCALDEV = true
PRINTER_0_DEVICE = /dev/usb/lp1
PRINTER_0_TYPE   = U
for the application MAC address

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