Linux Terminal Server Project - The LTSP Client Boot Process

The LTSP Client Boot Process

1. On the LTSP server, a chroot environment is set up with a minimal Linux operating system and X environment.
2. Either a computer will boot from a local boot device (like a harddisk, CD-ROM or USB disk), where it loads a small Linux kernel from that device which initializes the system and all of the peripherals that it recognizes.
3. Or, the thin client will use PXE or NetBoot network booting, a part of the onboard Ethernet firmware, to request an IP address and boot server (the LTSP server) using the DHCP protocol. A PXE bootloader (PXElinux) is loaded which then retrieves a Linux kernel and initrd from a Trivial File Transfer Protocol (TFTP) service usually running on the LTSP server. Using the utilities in the initrd, the kernel will request a (new) DHCP IP address and the address of a server from which it can mount its root filesystem (the chroot mentioned above). When this information is retrieved, the client mounts the path on its root filesystem via either the Network File System (NFS) or Network Block Device (NBD) services running on the LTSP server.
4. The client then loads Linux from the NFS mounted root filesystem (or NBD filesystem image) and starts the X Window system. At this XDMCP login manager on the LTSP server. In case of the newer MueKow (LTSP v5.x) setup, the client first builds an SSH tunnel to the LTSP server's X environment, through which it will start the LDM (LTSP Display Manager) login manager locally. From this point forward, all programs are started on the LTSP server, but displayed and operated from the client.