Linux Terminal Server Project (LTSP) is a

free and open-source Free and open-source software (FOSS) is software available under a Software license, license that grants users the right to use, modify, and distribute the software modified or not to everyone free of charge. FOSS is an inclusive umbrella term ...

terminal server A terminal server connects devices with a serial port to a local area network (LAN). Products marketed as terminal servers can be very simple devices that do not offer any security functionality, such as data encryption and user authentication. ...

for

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

that allows many people to simultaneously use the same computer. Applications run on the server with a terminal known as a

thin client In computer networking, a thin client, sometimes called slim client or lean client, is a simple (low-Computer performance, performance) computer that has been Program optimization, optimized for Remote desktop, establishing a remote connectio ...

(also known as an

X terminal X, or x, is the twenty-fourth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''ex'' (pronounced ), plural ''exes''."X", ' ...

) handling input and output. Generally, terminals are low-powered, lack a hard disk and are quieter and more reliable than desktop computers because they do not have any moving parts. This technology is useful in schools as it allows the school to provide pupils access to computers without purchasing or upgrading expensive desktop machines. Improving access to computers becomes less costly as thin client machines can be older computers that are no longer suitable for running a full desktop OS. Even a relatively slow CPU with as little as 128 MB of RAM can deliver excellent performance as a thin client. In addition, the use of centralized computing resources means that more performance can be gained for less money through upgrades to a single server rather than across a fleet of computers. By converting existing computers into thin clients, an educational institution can also gain more control over how their students are using computing resources as all of the user sessions can be monitored on the server. See Epoptes (A Lab Management Tool). The founder and project leader of LTSP is Jim McQuillan, and LTSP is distributed under the terms of the

GNU General Public License The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

The LTSP client boot process

# On the LTSP server, a

chroot chroot is a shell (computer), shell command (computing), command and a system call on Unix and Unix-like operating systems that changes the apparent root directory for the current running process and its Child process, children. A program that i ...

environment is set up with a minimal Linux operating system and X environment. # Either: ## the computer will

boot A boot is a type of footwear. Most boots mainly cover the foot and the ankle, while some also cover some part of the lower calf. Some boots extend up the leg, sometimes as far as the knee or even the hip. Most boots have a heel that is clearl ...

James A. McQuillan
Chapter 1.1 from the LTSP 4.1 manual: The steps that the workstation will go through.
/ref> 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, or ## the thin client will use

PXE PXE may refer to: Science and technology * Pentium Extreme Edition, a variant of the Pentium D microprocessor * Preboot Execution Environment, booting computers via a network * Pseudoxanthoma elasticum, a genetic disease Other uses * Proof and Exp ...

Network booting Network booting, shortened netboot, is the process of booting a computer from a computer network, network rather than a local drive. This method of booting can be used by Router (computing), routers, diskless workstations and centrally managed c ...

, a part of the onboard Ethernet firmware, to request an IP address and boot server (the LTSP server) using the

DHCP The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a clie ...

protocol. A PXE bootloader (PXElinux) is loaded which then retrieves a Linux kernel and initrd from a

Trivial File Transfer Protocol The Trivial File Transfer Protocol (TFTP) is a simple Lockstep (computing), lockstep communication protocol for transmitting or receiving files in a client-server application. A primary use of TFTP is in the early stages of nodes booting on a l ...

(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. # 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 A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is usually completely enclosed except for the two portals common at each end, though there may be access and ve ...

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.

Scalability

Initially, the MILLE-Xterm project, funded by Canadian public agencies and school districts in the province of Quebec, created a version of LTSP integrating four subprojects: a portal (based on uportal), an open-source middleware stack, a CD with free software for Windows/Mac and, finally, MILLE-Xterm itself. The MILLE-Xterm project's goal was to provide a scalable infrastructure for massive X-Terminal deployment. MILLE means ''Modèle d'Infrastructure Logiciel Libre en Éducation'' (Free Software Infrastructure Model for Education) and is targeted at educational institutions. As of 2009, MILLE-Xterm was integrated back into the LTSP as LTSP-cluster, a project specializing in the large scale deployment of LTSP. One of the main differences between LTSP and LTSP-cluster is the integration of a web-based central control center that replaces the traditional "one configuration file per thin client" as is the method of client customization through LTSP's lts.conf file in the main LTSP. LTSP-cluster allows organizations to centrally manage thousands of thin clients and their parameters from a central location. In LTSP-cluster high-availability and high-performance thin-clients are specified through the optional use of redundant components. Services that can be load-balanced and made highly available are: * DHCP server * TFTP server * Boot servers (root filesystem for the thin clients) * Application servers * Control center (PostgreSQL database + web frontend) LTSP-Cluster can support Linux application servers as well as Windows application servers and provides a similar level of support, centralized management, high-availability, and load-balancing features for both platforms. Also included is support for virtual desktops for remote users using NX technology. The NX protocol can allow remote Windows and Linux sessions to be accessed from a web browser with very low bandwidth (40 kbit/s) requirements and tolerance for high-latency connections. The NX client runs on various operating systems including Linux, Mac, and Windows.

Fat clients

LTSP v5.x added support for a thin client type known as "fat clients". With the advent of inexpensive, relatively powerful computer hardware, the idea to run applications locally on the thin client while offering the manageability of a thin client solution became a reality. In the case of a LTSP fat client, the root filesystem is not a rudimentary chroot but a full Linux installation as a chroot. The fat client uses LDM to authenticate to the LTSP server and mounts user home directories using SSH and FUSE. The local CPU and RAM is used on the fat clients, which provides a few benefits. # the LTSP server does not suffer from users abusing resources and affecting the performance and availability of the LTSP server to other users # multimedia and 3D applications perform better and utilize less network bandwidth LTSP is unique in offering the ability for a computer to mount its root filesystem over a network and run applications locally. On the Windows platform, the closest equivalent solution is to use a technology like Intel vPro to run a client-side hypervisor and mount the root filesystem image using

iSCSI Internet Small Computer Systems Interface or iSCSI ( ) is an Internet Protocol-based storage networking standard for linking data storage facilities. iSCSI provides block-level access to storage devices by carrying SCSI commands over a TCP/IP ...

References

External links

* {{Linux Linux Servers (computing) Remote desktop X Window System Thin clients

The LTSP client boot process

Scalability

Fat clients

See also

References

External links