LTSP is the Linux Terminal Server Project.

In the space, the server is set up to network boot LTSP workstations. The workstations are set up with utilities, development tools, diagnostic tools, editors, office suite, etc.

You can log in using your account on epidural if you have one, or by pressing the "Login Guest" button to use the guest 'mhvuser' account.

If you use an account, the home directory on each workstation is the same home directory you have on epidural.

Technical Details

Normally, LTSP use "thin clients" which are dumb X Terminals to a main server. Since LTSP 5.2, there is support for "fat clients" as well - where programs run on the workstation computer instead of on the server. We're using this "fat client" support.

When a workstation boots, it PXE boots a Linux kernel with a squashfs rootfs image sent from the server. When you login, the login goes via the server & ssh. At login time, the server mounts your home folder with sshfs.

More information available in the Ubuntu docs.

Gotchas

Officially, LTSP fat clients are only supported in Ubuntu. We're running the Ubuntu plugin with a few tweaks for Debian.

The setup runs pretty well, although there are a few oddities (such as being unable to lock your screen.)

Administration

Key Files & Folders

• TFTP root for LTSP PXE boot is /var/lib/tftpboot/ltsp/i386/

• pxelinux config /var/lib/tftpboot/ltsp/i386/pxelinux.cfg/default specifies a boot menu w/ options for booting the workstation or booting the local disk.

• chroot used for building the LTSP boot image is /opt/ltsp/i386

• LTSP config file is /opt/ltsp/i386/etc/lts.conf

Adding a new program

There are many options for adding a new program to the workstation. If you don't have admin access then you may have to ask someone with admin access to do it for you.

Options:

• Install directly on the workstation, temporarily. Users w/ sudo access on the server have passwordless sudo on the client. You can install anything you like (RAM permitting), the squashfs overlay is temporary and will go away when the workstation restarts.

• Install on the server. For command-line tools you can always install them on epidural and just ssh to access it.

• Install permanently in the workstation image. On the server, you can chroot into the workstation image with

  sudo ltsp-chroot -pc --arch=i386

  Then you have a chroot in the workstation (with /proc & dpkg cache mounted.) You can get apt-get install anything you like, and/or edit configuration.

  When you're done, exit the chroot and rebuild the image:

  sudo ltsp-update-image --arch=i386

  Rebuilding the image takes ~10 minutes, which is why this approach is a bit awkward (but you don't permanently add an app very often.) Reboot the workstation to bring the new image up.

• Install permanently to your home folder. This is permanent, and you don't need any admin access.

Adding printers or other workstation-specific config

If you set a hostname on the workstation, you can easily define local printers or other machine-specific scripts or resources at /opt/ltsp/i386/etc/lts.conf.

You will need to run ltsp-update-image when done.

Alternative Workstation Images

If you want to build a different workstation (maybe XFCE4 or Ubuntu or something), there are additional command-line options for ltsp-build-image that let you specify different chroot names and/or architectures.