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LTSP

See Desktop Terminal

The LTSP network consists of around 10+ machines booting as thin clients from Netboot. They connect to the LTSP server (Hosts/yew) which runs the applications.

Structure

LTSP clients are bootstrapped off of Netboot which points them to the LTSP server on Hosts/yew. The clients use a Network Block Device root file system which is hosted on yew. Each client then tunnels an X session via ssh back to the LTSP server.

Maintenance

The server yew is maintained basically same as any other server, remember that any applications which are to be accesible to users are installed on the server it self.

Client Images

The raw client image is stored in /opt/ltsp/i386, this needs to be transformed in to a squashfs filesystem before the clients will be able to use it.

There are a couple of scripts for managing the the client directory:

• ltsp-build-image - Builds the raw image in /opt/ltsp/i386 only used for initialization.
• ltsp-update-sshkeys - If the server IP changes the keys in the client image need to be updated
• ltsp-update-kernels - Copy system kernel into the client and into /var/lib/tftpboot on yew
• ltsp-update-image - Rebuild the squashfs filesystem for clients from /opt/ltsp/i386
• ltsp-enter-chroot - Utility for maintaining the chroot also updates the squashfs image after maintenance

In order to update the client:

 sudo ltsp-enter-chroot i386

Kernel updates are a bit trickier as the scripts will copy the kernel and initrd into /var/lib/tftpboot on yew but the TFTP server which clients use is on Hosts/larch. Running sudo ltsp-update-kernels will update /var/lib/tftpboot on yew, the vmlinuz and initrd.gz need to be then moved to larch:/var/lib/tftpboot/ltsp/yew/.

Local Apps

Local applications are configured by installing the desired program in the chroot. The terminals are then configured via /var/lib/tftpboot/lts.conf on the LTSP server (yew).

Example lts.conf:

 [Default]
   LOCAL_APPS=true
   LOCAL_APPS_MENU=true
   LOCAL_APPS_EXTRAMOUNTS=/net/groups

This enables local apps, overrides menu entries to launch the local application instead of the server side application, and additionally mount /net/groups from the server on the client.

All mounts are done via sshfs, the users home directory plus the extramounts are mounted on the client. Because it is sshfs they are secure to the user's login credentials, however there may be occasional issues with symlinks and other features which sshfs doesn't quite support.