LTSP
By Hector Gonzalez
LTSP
 LTSP stands for Linux Terminal Server Project.
 LTSP is an package for Linux that allows you to
connect lots of low-powered thin client terminals to
a Linux server. Applications typically run on the
server, and accept input and display their output
on the thin client display.
 Software and documentation is provided in
www.ltsp.org
 Last version released LTSP-4.2
LTSP concept
What is needed?
 A powerful server.
 A few low-power clients. PCs or
workstations.
 Network equipment.
 The server software (the client software is
contained in the server)
 The server is running his own operating
system (Fedora, for example).
What are the benefits of LTSP?
 Save money
– Software licenses.
– Powerful clients.
 Save time
– You do not need to configure each workstation, only
the boot configuration, because all the configuration is
in the server.
– If you have a PC, you have to set up updates, firewalls,
install new applications ...
 Open source
– LTSP provides documentation, you can learn about
Linux configuration and networking while you are
implementing LTSP.
What are the withdrawals of
LTSP?
 Your server OS must be Linux.
– Mostly all distributions are supported.
 Your client OS is going to be Linux.
 You have to setup the server
– Linux configuration could be confusing.
 Only Linux applications can run.
– But you could use a Windows emulator (WINE).
 Linux environment
– Not everybody knows how to work in a Linux
environment.
– Less friendly environment than windows.
Server requirements example
 Disk space
– Besides the OS you need about 100 MB for the LTSP software.
– User data.
 Example: 25 users, 5 GB per user => 125 GB
 RAM
– 4GB of RAM, 50 workstations.
 Processors
– Pentium 4, 2.4 GHZ, 50 workstations.
 Ethernet NIC
– Linux compatibility.
 Other hardware attached to the server
– Printers, CD/DVDs writers.
Client hardware
 Low-powered computers.
– Low processor capabilities, low RAM, low
hard disk or even without hard disk.
– A 90MHz Pentium with 16MB RAM is a good
one.
– It is possible to start a computer without hard
disk.
 Workstations.
– LTSP.org provides a list of tested workstations
[see].
Workstation example




LTSP Term 140
200 MHz processor
64 MB ram
1280x1024 at 16 bit
colour video resolution
 Requires LTSP v4.1
 Boots via PXE
 Price $224.95
Other solutions
 Traditional Windows PC
– PCs are too expensive.
– Expensive to maintain. 35 workstations would require at least 1
full-time system administrator.
– License management problems.
– Proprietary solution depending on vendor.
– Future software upgrades mean upgrading ALL desktops.
 Windows Based Terminal
– Based on Microsoft Windows
– Proprietary solution depending on vendor
– Expensive Per-User licensing
 Full PC based on Linux
– Lower initial cost than option the options above
– Too much hardware at each desktop. No need for the Hard drive,
CDRom or Floppy.
– Expensive to maintain. A workstation failure would result in
downtime for the user.
How much can you save?
Cost comparison for 35 computers
30000
Windows PCs
25000
20000
15000
10000
Workstation
5000
Old used PCs
0
$28,000
*DELL OptiPlex
$7,875
*Term 140
$1,750
*Pentium I or II
Installation
 There are three phases to building an LTSP
server:
– Installing the LTSP utilities
– Installing the LTSP client packages
– Configuring the services needed by LTSP
Installing the LTSP utilities
 Includes utilities for installing and managing the
LTSP client packages, and for configuring the
services on the LTSP server.
 The last version is LTSP 4-2.
 Availability in several formats
– tgz, rpm, dev
 About 40KB.
 You can download the rpm version from
– http://ltsp.mirrors.tds.net/pub/ltsp/utils/ltsp-utils-0.250.noarch.rpm
 Other formats can be found in:
– http://www.ltsp.org/download/
 Install the package:
– rpm -ivh ltsp-utils-0.25-0.noarch.rpm
Installing the LTSP client
packages
 Run the “ltspadmin” command in a shell.
 You will see the administration window.
 Choose "Install/Update" option to install the
packages.
Installing the LTSP client
packages (2)
The LTSP Installer configuration window will
appear.
Installing the LTSP client
packages (3)
 The options that you have are:
– Select the source of the packages.
 If your computer is connected to Internet type
http://ltsp.mirrors.tds.net/pub/ltsp/ltsp-4.2/
 Else you have to download the files and save them in a file. For the LTSP
4-1 version and below you can download the ISO file and burn it into a
CD (http://sourceforge.net/project/showfiles.php?group_id=17723). After
you have to specify your source, for example file:///media/cdrecorder if is
a CD.
– Directory of the client tree.
 Accept the default value
– Http proxy URL.
 If your connections go through one, specify the URL. Otherwise
accept the default options
– FTP proxy.
 The same than before.
Installing the LTSP client
packages (4)
 Press “a” to select all components and “q” to
install them.
Configuring the services needed
by LTSP
 LTSP relys on 4 services:
– DHCP [Dynamic Host Configuration Protocol]: used to
lease IPs to clients.
– TFTP [Trivial Transfer File Protocol]: to transfer files to
clients, like the client software.
– NFS [Network File System]: used to mount remote
directories.
– XDMCP [X Display Manager Controller Protocol]: used to
implement graphical login displays.
Configuring the services needed
by LTSP (2)
 Type “ltspcfg”.
 That are the options you have to configure:
Configuring the services needed
by LTSP (3)
 Runlevel
– Select runlevel 5 to indicate that your system is in
graphical mode in a network.
 Interface selection
– Select the current NIC
 DHCP
– It will create a default dhcpd.conf file and run the service.
 TFTP
– Enable the service
 Portmapper
– Used by RPC services, such as NFS
Configuring the services needed
by LTSP (4)
 NFS
– It will create the default configuration file and start the
service.
 XDMCP
– Allow graphical logins in the client. Enable it.
 Create /etc/hosts entries
– Some services like NFS need to be able to map the IP of
a workstation to a host name. Create the entries.
 Create /etc/host.allow entries
– This file provides security. Create it.
 Create the /etc/exports file
– This file is used by NFS to determine which directories
are allowed to be mounted by remote machines. Create
it.
Configuring the services needed
by LTSP (5)
 Create the lts.conf file
– The configuration of each workstation is in this file.
 Type “ltspcfg” and “s” to check the configuration.
Workstation specific configuration
 For your specific network there are 3 files you
need to edit.
– /etc/dhcpd.conf
 For the DHCP service.
– /etc/hosts
 For the name/IP address mapping.
– /opt/ltsp/i386/etc/lts.conf
 Specific configuration of the workstation.
 The explanation of how to edit
/etc/dhcpd.conf and /etc/hosts goes beyond
this paper.
Workstation specific configuration
(2)
 The file /opt/ltsp/i386/etc/lts.conf includes a default
configuration for the clients.
[Default]
SERVER
= 192.168.0.254
XSERVER
= auto
X_MOUSE_PROTOCOL = "PS/2"
X_MOUSE_DEVICE = "/dev/psaux"
X_MOUSE_RESOLUTION = 400
X_MOUSE_BUTTONS = 3
USE_XFS
=N
LOCAL_APPS
=N
RUNLEVEL
=5
Workstation specific configuration
(3)
 Use the default values but “SERVER”,
specify your server IP address.
Booting workstations
 Set up the workstations to boot up.
– Hard disk
– CD
– Floppy disk
– Network Interface Card
 Technologies
– PXE [Pre-boot eXecution Environment]
– Etherboot
Booting technologies
 PXE [Pre-boot eXecution Environment]
– Allows you to boot a computer without hard
disk or floppy disk or CD.
– It boots from network.
 You need a NIC.
– It is a feature available in most NICs.
– You have to enable PXE in the BIOS setup
– This is the process:
 Send DHCP requests.
 Get IP.
 Get the boot file.
Booting technologies (2)
 Etherboot
– A boot image is required for starting the boot
process.
– You create a boot image in a CD or floppy disk.
 Set up the BIOS to boot from CD/floppy disk.
 http://www.Rom-O-Matic.net/
– You also can create the boot image in the NIC
 The boot program is written in an EPROM memory.
 The EPROM is inserted in a socket in the NIC.
 Set up the BIOS to boot from a LAN.
 http://www.Rom-O-Matic.net/
Motivation
 The idea of processing all the tasks in the servers
is a new concept.
 It can be used in a lot of environments, for
example in cyber-cafes, universities, virtual
kiosks, terminal access...
 You can do it at home by yourself.
 It does not necessarily requires a lot of money.
 It is a Linux technology. Nowadays a lot of
companies, governments are moving to Linux.
 I have seen this before but I did not know the
technology underlying.
Future works
 Problems configuring the DHCP service in
Fedora.
 Install WINE or any other Windows emulator
to provide Windows applications use.
 Find a source with the hardware required in
the server according to the applications
running/number of clients.
 Escalate the number of servers.
Problems
 I downloaded the DHCP service from
ftp://download.fedora.redhat.com/pub/fedora/linux/
core/updates/2/SRPMS/dhcp-3.0.1rc14-1.src.rpm
 I installed it and could have the service installed
and enabled, but not running.
 I tried to start the service manually with “service
dhcpd start”, but I got error message. Actually I got
[failed].
 I tried uninstalling and downloading packages, but
the result was the same.
 I used sample configuration files, with the real
parameters of the network, but it did not work.
Problems 2
 I checked online several times and I did not find
any explanation to the problem.
 I installed the LTSP and DHCP server in other
computer without the Linux configuration done in
the labs and I got the same problems.
 I had into account the fact of the server had 2 NIC
cards and maybe it could create conflicts ?, but I
did not find any relevant.
 I do not know what is the problem.
 I considered the idea of installing another
distribution, but I did not for reasons of time.
Problems 3
 In that point I gave up with the DHCP
configuration.
 The ROM for booting the remote computers
was online in www.rom-o-matic.net , but
without the DHCP service enabled, the
client did not work.
Conclusion
 Remote execution of process is an interesting
concept with a lot of applications in the real life.
 You can save money in hardware and in licenses.
 Linux configuration can be tough but
documentation is provided by www.ltsp.org.
 Other solutions are either inefficient or more
expensive.
 The the LTSP software provides an administrator
tool for installing/monitoring the software.
 Computers without hard disk can be booted from
a server using either PXE or Etherboot.
Resources
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www.ltsp.org
www.disklessworkstations.com
www.Rom-O-Matic.net
www.google.com
Linux Toys 2