Linux Terminal Server Project

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The Linux Terminal Server Project ( LTSP ) is a Linux - program package , which serves users of terminals to access the terminal server to grant performed from which applications and can be controlled by means of the terminal. Areas of application are, for example, internet cafes or offices, where the same applications are available at every workstation and the costs per workstation should be kept low. The effect of minimizing costs arises from the fact that no fast systems and sometimes no hard drives have to be kept for the terminals. LTSP is free software and its publication is under the GPLv2 license.

Terminals

The terminals can consist of old, inefficient computers (e.g. Pentium I with 90 MHz , without hard drive , 100 Mbit network card , graphics card ; an existing PCI bus makes hardware recognition easier ) or of dedicated thin clients . Any Linux distribution can be used as the host operating system . The boats of the terminals via PXE -enabled network cards, via floppy disk or CD-ROM .

Technology used

X server

From a technical point of view, LTSP simplifies the use of the capabilities of the graphical X server to separate any Linux program into the two parts program execution and display. The program is executed on a high-performance server , while the display, together with input via keyboard or mouse , can take place on any number of terminals . The number of thin clients is determined by the transmission rate of the network and the performance of the server.

Local devices

For the use of local devices on the thin clients, LTSP uses its own development, a mixture of udev and FUSE . With this it is possible to connect USB mass storage devices, CD-ROMs and floppy disks to the clients and read them out on the server.

Advantages and disadvantages

LTSP has the same advantages and disadvantages that every terminal server installation brings with it.

Further specific advantages:

  • Support of local sound cards (built into the thin client) and local storage media such as USB sticks or CD-ROMs .
  • Possibility of inexpensive equipment for schools and internet cafés . An example of a Linux distribution for schools with a pre-installed Linux Terminal Server is Edubuntu .
  • The thin clients do not require any software other than the BIOS , i.e. no other systems or programs in a ROM . They therefore do not need to be updated and can be used for decades. Old PCs can also serve as thin clients.
  • Administrators can carry out almost all administration tasks on the system graphically on the thin client.

3D and video

Since the actual applications are executed on the server and the output is displayed on the clients via a remote X server on the client via an Ethernet connection, problems arise, e. B. when using OpenGL technology. Adapted graphics card drivers provide a DRI (Direct Rendering Interface) with which applications can send 3D instructions directly to the graphics card via the internal computer bus. If the graphics card is physically separated from the application, i.e. not in the same computer system, this fast method of 3D display is not possible. This is the case in LTSP systems. Nevertheless, the X server system offers the possibility of sending 3D instructions to the graphics card without having to calculate the result locally. The prerequisite is of course an X server with drivers that support 3D functions ( proprietary to NVIDIA and ATI ).

3D applications can therefore be mapped on the thin clients, but dependent on the Ethernet connection, since all OpenGL commands are sent over the network.

Games with relatively simple 3D requirements such as X-Moto can be viewed over a 100 Mbit connection.

3D modeling applications do not entirely fall into this field, as the final 3D calculation is carried out by software rendering engines. However, the OpenGL functionality of the XServer is actually used during the modeling. Blender can be operated well via LTSP and sensible graphics card drivers, for example.

The same applies to the video display. If the X server and the corresponding driver modules support a suitable video protocol such as XVideo ( not supported by the standard VESA module , for example ), good video display can be expected depending on the connection rate. With a 100 Mbit connection it is possible to watch an SVCD , but HDTV content is overwhelming even on a gigabit network.

LTSP version 4

Older LTSP versions make their own software packages of the Linux environment available for the clients through their project (kernel, libraries, x-server etc.). These are optimized for minimalism, size and speed. A subsequent installation of programs on the clients (or their NFS environment) already causes difficulties due to the lack of package management such as RPM or APT .

Over time, not only did the server and desktop computers perform better, but also the thin clients. Clients with a performance below 300 MHz are now rather uncommon. As a rule, at least common monitors with a resolution> = 1280 × 1024 need to be operated, for which a graphics card with an AGP slot is common.

This also results in larger areas of work for the clients, such as "video decoding on client side", Irda control (infrared remote control), installation of proprietary graphics card drivers (for AIX , TV-Out , OpenGL, for example), use of local devices such as TV Cards etc.

LTSP version 5

The current LTSP versions provide the clients with an environment that corresponds to a regular Linux distribution. This means that the user can expand the Linux system of the thin clients as required and install packages as required. In this way, the clients can be expanded with better support for ACPI , Irda, etc. Since this has little in common with the original LTSP project, it was codenamed 'muekow'.

Differences between the versions

version LTSP 4 LTSP 5 (MueKow)
GUI export XDMCP ssh -X
Remote login ( X Display Manager ) KDM / GDM LTSP Display Manager (LDM)
Package form tarball In the distribution
Root file system NFS 3 NBD
Authentication XDMCP SSH

See also

Web links

Individual evidence

  1. ↑ http://www.ltsp.org/benefits/