LTSP - Linux Terminal Server Project - v4.1

James McQuillan


Revision History
Revision 4.1.3-en2004-06-20Revised by: jam

GNU/Linux makes a great platform for deploying diskless thin clients. The primary purpose of this document is to show you how to deploy thin clients using LTSP. But, this document also covers many issues with diskless workstations in general.

Table of Contents

Introduction Chapter 1. Theory of operation Chapter 2. Installing LTSP on the server Chapter 3. Setting up the workstation Chapter 4. Running the workstation

Chapter 5. Printing Chapter 6. Screen Scripts

Chapter 7. Troubleshooting Chapter 8. Kernels Chapter 9. lts.conf entries Chapter 10. Local Applications Chapter 11. Configuration examples Chapter 12. Other sources of information


The LTSP provides a simple way to utilize low cost workstations as either graphical or character based terminals on a GNU/Linux server.

In a traditional office setting, there are relatively high powered Intel based PC's spread around at every desk. Each with several gigabytes of hard disk space. Users store their own data on the local hard drives and backups are rarely (if ever) performed.

Does it really make sense to have a full computer at each desk?

We say no.

Fortunately, there is another way. Utilizing the LTSP, you can take very low-end PCs, remove the hard drive, floppy and CD-Rom, and add a bootable network card. Many network cards have bootrom sockets, just waiting for a bootrom to be inserted.

During the boot phase, the diskless workstation obtains its IP info and a kernel from the server, then mounts the root filesystem from the server via NFS.

The workstation can be configured in one of 3 modes:

The really neat thing is that you can have lots of workstations served by a single GNU/Linux server. How many workstations? Well, that depends on the size of the server, and the applications that will be used.

It's not unusual to have 50 workstations, all running Mozilla and OpenOffice from a Dual P4-2.4 with 4GB of ram. We know this works. In fact, the load-average is rarely above 1.0!

1. Disclaimer

Neither the author nor the distributors, or any other contributor of this document are in any way responsible for physical, financial, moral or any other type of damage incurred by following the suggestions in this text.

2. Copyright and License

This document is copyright 2004 by James McQuillan, and is released under the terms of the GNU Free Documentation License, which is hereby incorporated by reference. The GNU Free Documentation License can be found at

Chapter 1. Theory of operation

Booting a diskless workstation involves several steps. Understanding what is happening along the way will make it much easier to solve problems, should they arise.

There are four basic services required to boot an LTSP workstation. They are:

LTSP is very flexible. Each of the above services can be served from the same server, or from several different servers. For our example, we'll describe a simple setup which consists of a single server, handling all of the above services.

1.1. The steps that the workstation will go through

  1. Load the linux kernel into the memory of the workstation. This can be done several different ways, including:
    1. Bootrom (Etherboot,PXE,MBA,Netboot)
    2. Floppy
    3. Hard disk
    4. CD-ROM
    5. USB Memory device

    Each of the above booting methods will be explained later in this chapter.

  2. Once the kernel has been loaded into memory, it will begin executing.
  3. The kernel will initialize the entire system and all of the peripherals that it recognizes.
  4. This is where the fun really begins. During the kernel loading process, a ramdisk image will also be loaded into memory. A kernel command line argument of root=/dev/ram0 tells the kernel to mount the image as the root directory.
  5. Normally, when the kernel is finished booting, it will launch the init program. But, in this case, we've instructed the kernel to load a small shell script instead. We do this by passing init=/linuxrc on the kernel command line.
  6. The /linuxrc script begins by scanning the PCI bus, looking for a network card. For each PCI device it finds, it does a lookup in the /etc/niclist file, to see if it finds a match. Once a match is found, the name of the NIC driver module is returned, and that kernel module is loaded. For ISA cards, the driver module MUST be specified on the kernel command line, along with any IRQ or address parameters that may be required.
  7. A small DHCP client called dhclient will then be run, to make another query from the DHCP server. We need to do this separate user-space query, because we need more information than the bootrom retrieved with the first dhcp query.
  8. When dhclient gets a reply from the server, it will run the /etc/dhclient-script file, which will take the information retrieved, and configure the eth0 interface.
  9. Up to this point, the root filesystem has been a ram disk. Now, the /linuxrc script will mount a new root filesystem via NFS. The directory that is exported from the server is typically /opt/ltsp/i386. It can't just mount the new filesystem as /. It must first mount it as /mnt. Then, it will do a pivot_root. pivot_root will swap the current root filesystem for a new filesystem. When it completes, the NFS filesystem will be mounted on /, and the old root filesystem will be mounted on /oldroot.
  10. Once the mounting and pivoting of the new root filesystem is complete, we are done with the /linuxrc shell script and we need to invoke the real /sbin/init program.
  11. Init will read the /etc/inittab file and begin setting up the workstation environment.
  12. One of the first items in the inittab file is the rc.sysinit command that will be run while the workstation is in the 'sysinit' state.
  13. The rc.sysinit script will create a 1MB ramdisk to contain all of the things that need to be written to or modified in any way.
  14. The ramdisk will be mounted as the /tmp directory. Any files that need to be written will actually exist in the /tmp directory, and there are symbolic links pointing to these files.
  15. The /proc filesystem is mounted.
  16. The lts.conf file will be parsed, and all of the parameters in that file that pertain to this workstation will be set as environment variables for the rc.sysinit script to use.
  17. If the workstation is configured to swap over NFS, the /var/opt/ltsp/swapfiles directory will be mounted as /tmp/swapfiles. Then, if there isn't a swapfile for this workstation yet, it will be created automatically. The size of the swapfile is configured in the lts.conf file.
  18. The swapfile will then be enabled, using the swapon command.

  19. The loopback network interface is configured. This is the networking interface that has as its IP address.
  20. If Local apps is enabled, then the /home directory will be mounted, so that the apps can access the users home directories.
  21. Several directories are created in the /tmp filesystem for holding some of the transient files that are needed while the system is running. Directories such as:
    1. /tmp/compiled
    2. /tmp/var
    3. /tmp/var/run
    4. /tmp/var/log
    5. /tmp/var/lock
    6. /tmp/var/lock/subsys

    will all be created.

  22. The /tmp/syslog.conf file will be created. This file will contain information telling the syslogd daemon which host on the network to send the logging information to. The syslog host is specified in the lts.conf file. There is a symbolic link called /etc/syslog.conf that points to the /tmp/syslog.conf file.
  23. The syslogd daemon is started, using the config file created in the previous step.
  24. Once the rc.sysinit script is finished, control returns back to the /sbin/init program, which will change the runlevel from sysinit to 5.
  25. This will cause any of the entries in the /etc/inittab file to be executed.

  26. By default, there are entries in inittab to run the /etc/screen_session script on tty1, tty2 and tty3. That means that you can run 3 sessions at a time, and the type of session is controlled by the SCREEN_01, SCREEN_02 and SCREEN_03 entries in lts.conf.
  27. More entries can be setup in inittab for more sessions, if desired.

  28. If SCREEN_01 is set to a value of startx , then the /etc/screen.d/startx script will be executed, which will launch the X Windows System, giving you a graphical user interface.
  29. In the lts.conf file, there is a parameter called XSERVER. If this parameter is missing, or set to "auto", then an automatic detection of the video card will be attempted. If the card is PCI or AGP, then it will get the PCI Vendor and Device id, and do a lookup in the /etc/vidlist file.

    If the card is supported by Xorg 6.7, the pci_scan routine will return the name of the driver module. If it is only supported by XFree86 3.3.6, pci_scan will return the name of the X server to use. The startx script can tell the difference because the older 3.3.6 server names start with 'XF86_', whereas the newer Xorg X server modules are typically lowercase names, like ati or trident .

  30. If Xorg is used, then the /etc/build_x4_cfg script will be called to build an XF86Config file. If XFree86 3.3.6 is used, then /etc/build_x3_cfg will be called to build the XF86Config file. These files are placed in the /tmp directory. Which, if you'll remember, is a ramdisk, seen only by the workstation.
  31. The XF86Config file will be built, based on entries in the /etc/lts.conf file.

  32. Once the XF86Config file has been built, then the startx script will launch the X server with that new config file.
  33. The X server will send an XDMCP query to the LTSP server, which will offer a login dialog.
  34. At this point, the user can log in. They'll get a session on the server.
  35. This confuses many people at first. They are sitting at a workstation, but they are running a session on the server. All commands they run, will be run on the server, but the output will be displayed on the workstation.

1.2. Loading the kernel into memory

Getting the Linux kernel into the workstations memory can be accomplished in a variety of ways.

1.2.1. Boot ROM

1.2.2. Local media

Chapter 2. Installing LTSP on the server

LTSP is best thought of as a complete distribution of Linux. It's a distribution that sits on top of a host distribution. The Host distro can be any Linux distro that you want. In fact, there's no real requirement that the host be running Linux. The only requirement is that the host system needs to be able to serve NFS (Network File System). Almost any Unix system can handle that. In fact, even some versions of Microsoft Windows can be configured to work as a LTSP server.

There are three phases to building an LTSP server.

2.1. Installing the LTSP utilities

Starting with version 4.1, LTSP has a package of utilities for installing and managing the LTSP client packages (The stuff that is executed on the thin clients), and for configuring the services on the LTSP server.

The administration utility is called ltspadmin and the configuration tool is called ltspcfg. Both of these tools are part of the ltsp-utils package.

The ltsp-utils package is available in both RPM and TGZ formats. Choose which format you prefer to install, and follow the appropriate instructions.

2.1.1. Installing the RPM package

Download the latest release of the ltsp-utils RPM package, and install it using the following command:

rpm -ivh ltsp-utils-0.1-0.noarch.rpm
The above commands will install the utilities on the server.

2.1.2. Installing the TGZ packages

Download the latest release of the ltsp-utils TGZ package and install it using the following commands:

tar xzf ltsp-utils-0.1-0.noarch.tgz
cd ltsp_utils
cd ..
The above commands will install the utilities on the server. This is useful for non-RPM based systems.

2.2. Installing the LTSP client packages

Once the installation of the ltsp-utils package is complete, you can run the ltspadmin command. This utility is used to manage the LTSP Client packages. It will query the LTSP download repository, and get the list of currently available packages.

Run the ltspadmin command and you'll see a screen like the following:

Figure 2-1. LTSP installer - Main Screen

From this screen, you can choose "Install/Update", and if this is your first time running the utility, it will display the installer configuration screen.

Figure 2-2. LTSP installer - Configuration Screen

In the configuration screen, you can set several values that the installer will use, for downloading and installing the LTSP packages. Those values are:

Where to retrieve packages from

This is a URL, pointing to the the package repository. Typically, this would be, but if you want to install the packages from a local filesystem, you can use the file: instead. For instance, if the packages are on a CD-ROM, and you've mounted the CD-ROM on /mnt/cdrom, then the value for the package repository would be: file:///mnt/cdrom. (Notice the 3 slashes).

In which directory would you like to place the LTSP client tree

This is the directory on the server, where you'd like to put the LTSP client tree. Typically, this would be: /opt/ltsp. The directory will be created, if it does not already exist.

Within this directory, the root directories for each architecture will be created. Currently, only x86 workstations are officially supported by LTSP, but there are several people working on ports to other architectures, such as PPC and Sparc.

HTTP Proxy

If the server is behind a firewall, and all web access must go through a proxy, you can configure the installer to use the proxy here. The value should contain the URL to the proxy, including the protocol and the port. An example for this setting is:

If you don't need a proxy, you should set this to " none".

FTP Proxy

For packages located on an FTP server, if you need to go through an FTP proxy, you can enter it here. The syntax is similar to the HTTP Proxy option above.

If you don't need a proxy, you should set this to " none".

Once you get past the configuration screen, the installer will query the package repository, and obtain the list of currently available components.

Figure 2-3. LTSP installer - Component list

Select each component that you want to install. To select it, move the high-lighted line to that component, and press 'I ' to select the individual component. You can also press ' A' to select ALL of the components. Most of the time, this will be what you want. That way, you can support the broadest range of thin client hardware.

There are several keys that can be used to navigate around this screen. You can get help on those keys by pressing the ' H' key.

Figure 2-4. LTSP installer - Help window

If you want to see the list of packages that are in a particular component, you can press 'S', and the list of packages will be displayed. It will show the version currently installed, and also the latest available version.

Figure 2-5. LTSP installer - Package list

Once the desired components are selected, you can exit the component selection screen. The installer will prompt you, to see if you really want to install/update the selected packages. If you answer ' Y', then it will download and install the selected packages.

2.3. Configuring the services needed by LTSP

There are four basic services required to support the booting of an LTSP workstation. They are:

The ltspcfg can be used to configure all of those services, plus many other LTSP related things.

You can access ltspcfg from the ltspadmin, or you can run ltspcfg by typing it at the command line.

When you run the ltspcfg utility, it will scan the server, to assess what is currently installed and running. You'll see a screen like:

Figure 2-6. ltspcfg - Initial screen

This shows all of the things that the utility is looking for.

To configure all of the things that need to be setup, choose ' C', and the configuration menu will be displayed. From the configuration menu, you'll need to go through each item, to make sure it is configured properly for serving LTSP workstations.

Figure 2-7. ltspcfg - Initial screen

1 - Runlevel

The Runlevel is variable used by the init program. With Linux and Unix systems, at any given time, the system is said to be in a specific "Runlevel". Runlevel 2 or 3 is typically used when the server is in text mode. Runlevel 5 typically indicates the system is in graphical mode on a network.

For an LTSP server, traditionally Runlevel 5 is used. Most systems are already configured to serve NFS and XDMCP when in Runlevel 5. For those systems that aren't already configured for that, this utility will take care of them.

2 - Interface selection

For systems that have multiple network interfaces, you'll need to specify which interface the Thin clients are connected to.

By selecting the interface, the configuration tool will be able to properly create other configuration files, such as the dhcpd.conf and the /etc/exports files.

3 - DHCP configuration

DHCP needs to be configured to supply the required fields to the workstation. Among those fields are fixed-address , filename, subnet-mask, broadcast-address and root-path.

By selecting this menu item, you'll be able to create the dhcpd.conf configuration file, and enable dhcpd to run at startup time.

4 - TFTP configuration

TFTP is used by the thin client to download the Linux kernel. The tftpd service needs to be enabled on the server, to serve up the kernel.

5 - Portmapper configuration

The Portmapper is used by RPC services. Each RPC service, such as NFS.

6 - NFS configuration

NFS is the service that allows local directory trees to be mounted by remote machines. This is required for LTSP, because the workstations mount their root filesystems from the server.

This menu item will take care of configuring NFS to start at boot time. The configuration file is /etc/exports and its creating is described later in this section.

7 - XDMCP configuration

XDMCP is the "X Display Manager Control Protocol". The X server sends an XDMCP query to the Display manager on the server, to get a login prompt.

Common display managers in use are XDM, GDM and KDM. This menu item will display which display managers are found, and which one is configured to run.

For security purposes, the Display manager is configured by default to NOT allow remote workstations to connect. This is usually the reason for the infamous Gray screen with large X cursor. ltspcfg can usually configure the display manager to allow remote workstations to get a connection.

8 - Create /etc/hosts entries

Many services, like NFS and the Display manager need to be able to map the IP address of the workstation to a host name. You could setup the Berkeley Internet Naming Daemon (BIND) to do that, but you'd have to make sure you get the reverses setup properly. Ultimately, using bind is probably the best way to do it, but configuration of bind is beyond the scope of this document and the ltspcfg utility.

A much simpler approach for configuring the mapping of IP addresses and host names is the /etc/hosts file.

9 - Create /etc/hosts.allow entries

Some services use a layer of security known as tcpwrappers . This is configured through the /etc/hosts.allow file. This menu item will setup that file for you.

10 - Create the /etc/exports file

This is the file that NFS uses, to determine which directories are allowed to be mounted by remote machines. This menu item will create that file.

11 - Create the lts.conf file

The configuration of each workstation is directed by entries in the lts.conf file. For fairly modern workstations with a PCI bus, it shouldn't require any additional entries in the lts.conf file. But, the file still needs to exist. This menu item will create the default lts.conf file for you.

2.4. Workstation specific configuration

Now, it's time to tell the LTSP server about your specific workstation. There are three files that contain information about the workstation.

  1. /etc/dhcpd.conf
  2. /etc/hosts
  3. /opt/ltsp/i386/etc/lts.conf

2.4.1. /etc/dhcpd.conf

The workstation needs an IP address and other information. It will get the following from the DHCP server:

For our example LTSP environment, we have chosen DHCP for handling IP address assignment to the workstations.

During the ltsp_initialize script, a sample dhcpd.conf file is installed. It is called /etc/dhcpd.conf.example you can copy that file to /etc/dhcpd.conf to use it as a basis for your dhcp configuration. You will need to modify the parts of this file that pertain to your specific workstation and server environment.

default-lease-time            21600;
max-lease-time                21600;
option subnet-mask  ;
option broadcast-address;
option routers      ;
option domain-name-servers;
option domain-name            "";
option root-path              "";
shared-network WORKSTATIONS {
    subnet netmask {
group	{
    use-host-decl-names       on;
    option log-servers;
    host ws001 {
        hardware ethernet     00:E0:18:E0:04:82;
        filename              "/lts/vmlinuz.ltsp";

Figure 2-8. /etc/dhcpd.conf

As of LTSP, version 2.09pre2, you no longer have to specify a particular kernel to load. The standard kernel package supports all of the network cards that Linux supports. There are two kernel files included in the LTSP kernel package. One kernel has the Linux Progress Patch (LPP) applied, and the other kernel does not. The names for the kernels are:


You may have noticed that the kernel is sitting in the /tftpboot/lts directory, but in the "filename" entry in the /etc/dhcpd.conf file is missing the leading /tftpboot component of the pathname. That is because on Redhat versions 7.1 and above, TFTP is run with the '-s' option. That causes the tftpd daemon to run in secure mode. That is, it does a chroot to the /tftpboot directory when it starts. Therefore, all files that are available to the tftpd daemon are relative to the /tftpboot directory.

Other Linux distributions may not have the '-s' option set for tftpd, so you will need to add the /tftpboot prefix to the kernel pathname.

2.4.2. /etc/hosts

IP address to hostname mapping

Computers generally communicate just fine with IP addresses. Then, us humans come along and need to put names on the computers, because we can't remember the numbers. That's where DNS or the /etc/hosts file come into play. This IP address to hostname mapping generally isn't required, except in an LTSP environment. That's because without it, NFS will give you permissions errors when the workstation attempts to mount the root filesystem.

In addition to NFS problems, if the workstation is not listed in the /etc/hosts file, you may also have problems with the GDM or KDM display managers.

2.4.3. /opt/ltsp/i386/etc/lts.conf

There are a number of configuration entries that can be specified in the lts.conf file.

The lts.conf file has a simple syntax, that consists of multiple sections. There is a default section called [default] and there can be sections for individual workstations. The workstations can be identified by hostname, IP address or MAC address.

A typical lts.conf file looks like this:

# Config file for the Linux Terminal Server Project (

        SERVER             =
        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

        USE_NFS_SWAP       = Y
        SWAPFILE_SIZE      = 48m
        RUNLEVEL           = 5

        XSERVER            = XF86_SVGA
        LOCAL_APPS         = N
        USE_NFS_SWAP       = Y
        SWAPFILE_SIZE      = 64m
        RUNLEVEL           = 3

Example 2-1. lts.conf file

The following is a list of some of those entries:


If your video card is a PCI card, and if it is supported by 6.7.0, then you just need the lts_x_core package. That contains all of the driver modules for X4.

There are several XFree86 3.3.6 packages available for LTSP. This is in case your card isn't supported by 6.7.0.

You can make entries in the lts.conf for each individual workstation, or you can make default entries that are shared by all workstations.

Our workstation has an Intel i810 video chipset, and it can correctly be auto detected, so we don't need any XSERVER entry in the lts.conf file. The XSERVER entry can be specified, if you want, or it can be set to 'auto' to show that it is going to be auto detected.


We want to run the workstation in graphical mode, so we need to set the runlevel to '5'. This is done by another entry in the lts.conf file.

2.5. Displaying the current configuration

With ltspcfg, you can get a look at the current status of all of the services required by LTSP. From the ltspcfg main menu, press 'S', and you will see the current status.

Figure 2-9. ltspcfg - Current Status

Chapter 3. Setting up the workstation

Once the server is setup, it is time to focus on setting up the workstation.

The LTSP project is all about what happens after the kernel is in memory. There are several ways to get the kernel into memory, including Etherboot, Netboot, PXE and floppy disk.

3.1. Booting with PXE

If your network card or PC has PXE built into it, then you can use that to load the Linux kernel. PXE is a bootrom technology, similar to Etherboot or Netboot.

You may need to enable the PXE bootrom on your NIC. You may also need to change the boot device order in your BIOS, to make "Boot from LAN" the first choice, rather than booting from the floppy or the hard disk.

PXE has a limitation of only being able to load files that are 32kb or smaller. The Linux kernel is quite a bit larger than that, so you can't load the Linux kernel directly with PXE. You need to load something known as a 'Network Bootstrap Program' or NBP.

There is an NBP available for loading Linux kernels called pxelinux.0. This is part of the syslinux package from kernel developer H. Peter Anvin.

The LTSP kernel package includes the pxelinux.0 NBP and the configuration file needed to load the Linux kernel and an initial ramdisk image.

The way it works, is this:

3.2. Booting with Etherboot


Etherboot is a software package for creating ROM images that can download code over an Ethernet network to be executed on an x86 computer. Many network adapters have a socket where a ROM chip can be installed. Etherboot is code that can be put in such a ROM.

-- Ken Yap  

Etherboot is also Open Source, protected under the GNU General Public License, Version 2 (GPL2).

To use Etherboot, if you have a network card with an Etherboot bootrom, may need to change your BIOS configuration to tell it to "Boot from LAN" before booting from floppy or hard disk.

If you don't yet have an Etherboot bootrom, you can either make a bootrom, or you can make a floppy disk with an Etherboot image on its boot sector.

Etherboot supports a very large number of network cards. Over 200 models, with more being added all the time. Whether you choose to make a floppy or a burn the code to an EPROM, you'll need to determine which model network card you have.

3.2.1. Choosing an Etherboot driver for an ISA network card

For older ISA based network cards, it isn't so important that you determine the exact type. First of all, most of them are either ne2000 or 3Com 3c509 cards. You just need to pick the right Etherboot driver, the one that selects the correct media type on cards that both 10 base-2 (Coax) and 10 base-T (Twisted pair).

3.2.2. Choosing an Etherboot driver for a PCI network card

For PCI cards, it is important that you pick the Etherboot driver that matches the PCI Vendor and Device ID of the network card.

Sometimes, you'll get lucky. You'll know exactly which model card you have, because the model number is printed on the card, and it exactly matches the description of one of the Etherboot modules. But, in many cases, you will need to find the PCI ID numbers.

If your workstation has a floppy drive, you can boot a tomsrtbt (Tom's Root Boot) floppy. Or, if your workstation has a CD-ROM drive, you can boot a Knoppix CD. If you can't load linux on your workstation, then your only hope may be to move the network card to a machine that can boot Linux.

Once you have Linux booted, you can use the lspci command. with the '-n' option.

[root@jamlap root]# lspci -n
0000:00:00.0 Class 0600: 8086:7190 (rev 03)
0000:00:01.0 Class 0604: 8086:7191 (rev 03)
0000:00:03.0 Class 0607: 104c:ac1c (rev 01)
0000:00:03.1 Class 0607: 104c:ac1c (rev 01)
0000:00:07.0 Class 0680: 8086:7110 (rev 02)
0000:00:07.1 Class 0101: 8086:7111 (rev 01)
0000:00:07.2 Class 0c03: 8086:7112 (rev 01)
0000:00:07.3 Class 0680: 8086:7113 (rev 03)
0000:00:08.0 Class 0401: 125d:1978 (rev 10)
0000:01:00.0 Class 0300: 1002:4c4d (rev 64)
0000:06:00.0 Class 0200: 8086:1229 (rev 09)
In the example above, you can see an entry for each of the PCI cards in the system. You only need to look at the Class 0200 devices. So, running the command again, looking only at the Ethernet interfaces, the list becomes much more manageable.
[root@jamlap root]# lspci -n | grep "Class 0200"
0000:06:00.0 Class 0200: 8086:1229 (rev 09)
The PCI ID numbers are: 8086:1229. The first field, 8086 is the PCI Vendor ID. In this example, the vendor is the Intel Corporation. The second field, 1229 is the PCI Device ID. That tells us which model of the network card. In this case, it's an EtherExpress 100 card.

3.2.3. Creating a boot floppy

You can download the Etherboot package and configure it for the type of bootrom that you need. Then, you can compile the source to produce a bootrom image that can be written to an EPROM, or written to a floppy disk.

A much simpler approach is to go to Marty Connor's website.

Marty has done an excellent job of putting a web based front-end on the configuration and compilation process of making bootrom images with Etherboot. On his site, you select what type of network card you have, and what kind of image you want. Then, you have an opportunity to modify many Etherboot configuration options. Then, you can press the 'Get ROM' button and a custom bootrom image will be generated while you wait.

For the ROM output format, choose 'Floppy Bootable ROM Image'. This will cause it to include a 512 byte header that is a boot loader for loading the etherboot image into ram where it can be executed.

Press the 'Get ROM' button. The bootrom image will be generated while you wait. It only takes a few seconds, and when it completes, your browser will pop-up a "Save As" window where you can designate where you want the bootrom image to be saved on your computer.

Once you've saved the image to your hard drive, you need to write it out to a floppy disk. Insert a floppy diskette into the drive and run the following command to write the floppy:

dd if=Etherboot_Image of=/dev/fd0 

3.2.4. Creating a bootrom

Writing the Etherboot image to an EPROM requires an EPROM programmer. This is a piece of equipment that ranges in price from few hundred dollars to several thousand dollars, depending on the features.

The process of creating a bootrom is entirely dependent on the EPROM programmer. This is beyond the scope of this document.

Chapter 4. Running the workstation

Assuming that the server and workstation are configured properly, it should just be a matter of inserting the boot floppy in the floppy drive and turning on the workstation.

The Etherboot code will be read from the floppy into memory, the network card will be found and initialized, the dhcp request will be sent on the network and a reply will be sent from the server and the kernel will be downloaded to the workstation. Once the kernel has initialized the workstation hardware, X windows will start and a login box should appear on the workstation, similar to the example below.

Figure 4-1. Login screen

At this point, you can log in. An important thing to keep in mind is that you are logging into the server. All of the commands that you run are actually running on the server, and displaying their output on the workstation. That's the power of X windows.

You can run any program that is supported by the server.

Chapter 5. Printing

Aside from the workstation being a fully functioning GUI or character mode terminal, it can also act as a print server, allowing up to 3 printers to be attached to the parallel and serial ports.

This is all transparent to the user of the workstation. They won't even notice the small amount of traffic that is going through the workstation to the printers.

5.1. Client side setup

LTSP uses the lp_server program on the workstation, to redirect print jobs from the server to the printer attached to one of the ports on the workstation.

To enable the printer on the workstation, there are a set of configuration entries in the lts.conf file.

    PRINTER_0_DEVICE = /dev/lp0
    PRINTER_0_TYPE   = P 
The above entry will cause the lp_server program to run as a daemon, listening on TCP/IP port 9100 for a print stream from the server. The print data will then be redirected to the printer attached to the /dev/lp0 parallel port.

There are many more options available. Check the lts.conf section later in this document for more information on printer configuration entries.

5.2. Server side setup

Setting up the printer on the server is a matter of defining a print queue, using the printer configuration tool on the server.

On Redhat 7.2, there is both a GUI and a Text based printer configuration tool. The GUI tool is called printconf-gui, and the text based tool is called printconf-tui. Older versions of Redhat have a program called printtool. Printtool also exists on Redhat 7.2, but it will call printconf-gui. Other Linux distributions have their own printer configuration tool.

Figure 5-1. Printconf-gui Adding new printer

Once you launch the printer configuration tool, you need to add a new printer. The lp_server program allows the workstation to emulate an HP JetDirect print server. You just need to create a JetDirect printer.

You need to give the printer a Queue name. The name can be anything, but make it a meaningful name, and the name can contain only the following characters:

The name chosen in the example above is ws001_lp . This name makes it easy to see that the printer is associated with ws001.

Figure 5-2. Printconf-gui Detail info

There are two fields required to communicate with the printer:

  1. IP Address or hostname of the workstation that the printer is associated with.
  2. The TCP port that the lp_server daemon is listening on.
  3. The first printer you connect to a workstation will be on TCP/IP port 9100. The second printer will be on port 9101, and the third printer will be on port 9102 .

Chapter 6. Screen Scripts

A feature of LTSP that was added with version 4.0 is something called Screen Scripts. These are scripts for starting various types of sessions.

You can specify multiple screen scripts for a workstation. Doing so, will all you to have multiple sessions. They can be different types of sessions, or they can be the same type of session. For example, you could specify the following:

   SCREEN_01 = startx
   SCREEN_02 = shell
This would start an X server on the first screen, and a shell prompt on the second screen. You can switch between the screens by pressing Ctrl-Alt-F1 to get to the first screen, and Ctrl-Alt-F2 to get to the second screen.

You can specify up to 12 screen scripts for a workstation, but most people would just have a single one.

Available types of screen scripts:


This script will launch the Xserver with a -query option, to send an XDMCP request to a display manager to get a login dialog box to display on the screen.


This script will launch a shell on the terminal. This is really intended to be used for troubleshooting problems with the workstation. Because it gives you a session on the thin client, rather than the server, it isn't very useful for running applications.


This script will launch a telnet session that will connect to the server. This will give you a character based session on the server.

By default, telnet will connect to the LTSP server. If you want to specify a different server, you can pass it on the same line as the screen script. For example:

    SCREEN_01 = telnet
You can also specify any options that Telnet understands, But, if you do specify any options, then you must also specify the server to connect to.

This script will launch the rdesktop program, which will connect to a Microsoft Window server. You can specify any rdesktop options you want on the line, directly after the name of the screen script name. For example, if you want to specify the server to connect to, you can do it like this:

    SCREEN_01 = rdesktop -f
The above example will launch rdesktop in full screen mode. The user will see a windows login dialog, and they will only have to log in once. This is very useful when you just want to get a windows login, without having a Linux login or window manager. The user won't even know they are running Linux.

The screen scripts reside in the /opt/ltsp/i386/etc/screen.d directory. You can create your own screen scripts and place them in this directory. It's best to follow one of the existing scripts as an example.

Chapter 7. Troubleshooting

If, after following through the previous chapters, your workstation doesn't boot, then you've got to start the process of troubleshooting the installation.

The first thing to do is figure out how far through the boot process the workstation has gotten.

7.1. Troubleshooting Etherboot floppy image

When you boot from the floppy, you should see something similar to this:

loaded ROM segment 0x0800 length 0x4000 reloc 0x9400
Etherboot 5.0.1 (GPL) Tagged ELF for [LANCE/PCI]
Found AMD Lance/PCI at 0x1000, ROM address 0x0000
Probing...[LANCE/PCI] PCnet/PCI-II 79C970A base 0x1000, addr 00:50:56:81:00:01
Searching for server (DHCP)...

The above example shows what you can expect to see on the screen when booting from a floppy. If you don't see those messages, indicating that Etherboot has started, then you may have a bad floppy disk, or you didn't write the image to it properly.

If, you see a message like the following, then it probably indicates that the Etherboot image you have generated is not the correct image for your network card.

ROM segment 0x0800 length 0x8000 reloc 0x9400
Etherboot 5.0.2 (GPL) Tagged ELF for [Tulip]
Probing...[Tulip]No adapter found

If it does get to the point where it detects the network card and displays the proper MAC address, then the floppy is probably good.

7.2. Troubleshooting DHCP

Once the network card is initialized, it will send out a DHCP broadcast on the local network, looking for a DHCP server.

If the workstation gets a valid reply from the DHCP server, then it will configure the network card. You can tell if it worked properly if the IP address information is displayed on the screen. Here's an example of what it should look like:

ROM segment 0x0800 length 0x4000 reloc 0x9400
Etherboot 5.0.1 (GPL) Tagged ELF for [LANCE/PCI]
Found AMD Lance/PCI at 0x1000, ROM address 0x0000
Probing...[LANCE/PCI] PCnet/PCI-II 79C970A base 0x1000, addr 00:50:56:81:00:01
Searching for server (DHCP)...
Me:, Server:, Gateway 
If you see the line that starts with 'Me:', following by an IP address, then you know that DHCP is working properly. You can move on to checking to see if TFTP is working.

If instead, you see the following message on the workstation, followed by lots of <sleep> messages, then something is wrong. Although, it is common to see one or two <sleep> messages, after which the dhcp server replies.

Searching for server (DHCP)...  

Figuring out what is wrong can sometimes be difficult, but here are some things to look for.

7.2.1. Check the connections

Is the workstation physically connected to the same network that the server is connected to?

With the workstation turned on, make sure that the link lights are lit at all of the connections.

If you are connecting directly between the workstation and the server (no hub or switch), make sure that you are using a cross-over cable. If you are using a hub or switch, then make sure you are using a normal straight-through cable, both between the workstation and hub, and also between the hub and server.

7.2.2. Is dhcpd running?

You need to determine whether dhcpd is running on the server. We can find the answer a couple of ways.

dhcpd normally sits in the background, listening on udp port 67. Try running the netstat command to see if anything is listening on that port:

netstat -an | grep ":67 " 
You should see output similar to the following:
udp     0    0*
The 4th column contains the IP address and port, separated by a colon (':'). An address of all zeroes ('') indicates that it is listening on all interfaces. That is, you may have an eth0 and an eth1 interface, and dhcpd is listening on both interfaces.

Just because netstat shows that something is listening on udp port 67, it doesn't mean that it is definitely dhcpd that is listening. It could be bootpd, but that is unlikely, because bootp is no longer included on most distributions of Linux.

To make sure that it is the dhcpd that is running, try running the ps command.

ps aux | grep dhcpd 
You should see something like the following:
root 23814 0.0 0.3 1676 820 ?      S 15:13 0:00 /usr/sbin/dhcpd
root 23834 0.0 0.2 1552 600 pts/0  S 15:52 0:00 grep dhcp 
The first line shows that dhcpd is running. The second line is just our grep command.

If you don't see any lines showing that dhcpd is running, then you need to check that the server is configured for runlevel 5, and that dhcpd is configured to start in runlevel 5. On Redhat based systems, you can run the ntsysv and scroll down to make sure dhcpd is configured to start.

You can try starting dhcpd with this command:

service dhcpd start
Pay attention to the output, it may show errors.

7.2.3. Double-check the dhcpd configuration

Does the /etc/dhcpd.conf file have an entry for our workstation?

You should double-check the 'fixed-address' setting in the config file, to make sure it exactly matches the card in the workstation.

7.2.4. Is ipchains or iptables blocking the request? Checking for ipchains

Run the following command to see what it says:

ipchains -L -v 
If you see something like this:
Chain input (policy ACCEPT: 229714 packets, 115477216 bytes):
Chain forward (policy ACCEPT: 10 packets, 1794 bytes):
Chain output (policy ACCEPT: 188978 packets, 66087385 bytes): 
Then it isn't ipchains that is getting in the way. Checking for iptables

Run the following command to see what it says:

iptables -L -v 
If you see something like this:
Chain INPUT (policy ACCEPT 18148 packets, 2623K bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 17721 packets, 2732K bytes)
 pkts bytes target     prot opt in     out     source               destination
Then it is not iptables getting in the way.

7.2.5. Is the workstation sending the request?

Try watching the /var/log/messages file while the workstation is booting. You can do that with the following command:

tail -f /var/log/messages 
This will 'follow' the log file as new records are written to it.
server dhcpd: DHCPDISCOVER from 00:50:56:81:00:01 via eth0
server dhcpd: no free leases on subnet WORKSTATIONS
server dhcpd: DHCPDISCOVER from 00:50:56:81:00:01 via eth0
server dhcpd: no free leases on subnet WORKSTATIONS 
If you see messages like those above, saying 'no free leases', that indicates that dhcpd is running, but it doesn't know anything about the workstation that is requesting an IP address.

7.3. Troubleshooting TFTP

Etherboot uses TFTP to retrieve a Linux kernel from the server. This is a fairly simple protocol, but sometimes there are problems trying to get it to work.

If you see a message similar to this:

with the dots filling the screen rather quickly, that normally indicates that TFTP is working properly, and the kernel is downloading.

If, instead, you don't see the dots, there is a problem. Possible problems include:

7.3.1. tftpd is not running

If tftpd isn't configured to run, then it certainly won't be able to answer the request from the workstation. You can see if it is running, you can use the netstat command, like this:

[root@bigdog]# netstat -anp | grep ":69 "

udp     0   0*                 453/inetd        
If you don't see any output from that command, then tftpd is likely not running.

There are two common methods for invoking tftpd, They are inetd and the newer xinetd

inetd uses a configuration file called /etc/inetd.conf. In that file, make sure that the line for starting tftpd is NOT commented out. This is what the line should look like:

tftp dgram udp wait nobody /usr/sbin/tcpd  /usr/sbin/in.tftpd -s /tftpboot

xinetd uses a directory of individual configuration files. One file for each service. If your server is using xinetd, then the configuration file for tftpd is called /etc/xinetd.d/tftp. Below is an example:

service tftp
  disable          = no
  socket_type      = dgram
  protocol         = udp
  wait             = yes
  user             = root
  server           = /usr/sbin/in.tftpd
  server_args      = -s /tftpboot
Make sure that the disable line doesn't say yes.

7.3.2. Kernel not where tftpd expects to find it

The kernel needs to be in a location that the tftpd daemon can access it. If the '-s' option is specified for the tftpd daemon, then whatever the workstation is asking for must be relative to the /tftpboot. So, if the filename entry in the /etc/dhcpd.conf file is set to /lts/vmlinuz-2.4.24-ltsp-4, then the kernel actually needs to be /tftpboot/lts/vmlinuz-2.4.24-ltsp-4

7.4. Troubleshooting NFS root filesystem

There are several things that can prevent a root filesystem from being mounted. Including the following:

7.4.1. No init found

If you get the following error:

Kernel panic: No init found.  Try passing init= option to kernel.  
Then it is is most likely that either you are mounting the wrong directory as the root filesystem, or the /opt/ltsp/i386 directory is empty.

7.4.2. Server returned error -13

If you get the following error:

Root-NFS: Server returned error -13 while mounting /opt/ltsp/i386 
This indicates that either the /opt/ltsp/i386 directory isn't listed in the /etc/exports file.

Take a look in the /var/log/messages file to see if there are any clues. An entry like this:

Jul 20 00:28:39 bigdog rpc.mountd: refused mount request from ws004
                  for /opt/ltsp/i386 (/): no export entry 
Then it confirms our suspicion that the entry in /etc/exports isn't correct.

7.4.3. NFS Daemon problems (portmap, nfsd & mountd)

NFS can be a complex and difficult service to trouble-shoot, but understanding what should be setup and what tools are available to diagnose the problems will surely help to make it easier.

There are three daemons that need to be running on the server for NFS to work properly. portmap, nfsd and mountd. The Portmapper (portmap)

If you get the following messages:

Looking up port of RPC 100003/2 on
portmap: server not responding, timed out
Root-NFS: Unable to get nfsd port number from server, using default
Looking up port of RPC 100005/2 on
portmap: server not responding, timed out
Root-NFS: Unable to get mountd port number from server, using default
mount: server not responding, timed out
Root-NFS: Server returned error -5 while mounting /opt/ltsp/i386
VFS: unable to mount root fs via NFS, trying floppy.
VFS: Cannot open root device "nfs" or 02:00
Please append a correct "root=" boot option
Kernel panic: VFS: Unable to mount root fs on 02:00 
This most likely is caused by the portmap daemon not running. You can confirm whether or not the portmapper is running by using the ps command:
ps -e | grep portmap 
If the portmapper is running, you should see output like this:
30455 ?        00:00:00 portmap 
Another test is to use the netstat. The portmapper uses TCP and UDP ports 111. Try running this:
netstat -an | grep ":111 " 
You should see the following output:
tcp   0   0*          LISTEN      
udp   0   0*                           
If you don't see similar output, then the portmapper isn't running. You start the portmapper by running:
/etc/rc.d/init.d/portmap   start 
Then, you should make sure that the portmapper is setup to start when the server boots. Run ntsysv to make sure it is selected to run. The NFS and MOUNT daemons (nfsd & mountd)

NFS has 2 daemons that need to be running. nfsd and mountd. They are both started by the /etc/rc.d/init.d/nfs script.

You can run the ps command to make sure that they are running.

ps -e | grep nfs
ps -e | grep mountd 
If it shows that one or both of the daemons are not running, then you will need to start them.

Normally, you should be able to run the startup script with the restart argument to cause them both to startup, but for some reason, the /etc/rc.d/init.d/nfs script doesn't restart nfsd that way. It only restarts mountd (bug?). So, you should instead run the following sequence of commands:

/etc/rc.d/init.d/nfs  stop
/etc/rc.d/init.d/nfs  start 
You may get errors on the stop command, but that is OK. The start command should show OK as the status.

If the daemons are running, but NFS is still not working, you can verify that they have registered themselves with the portmapper by using the rpcinfo command.

rpcinfo -p localhost 
You should see results similar to the following:
program vers proto   port
 100000    2   tcp    111  portmapper
 100000    2   udp    111  portmapper
 100003    2   udp   2049  nfs
 100003    3   udp   2049  nfs
 100021    1   udp  32771  nlockmgr
 100021    3   udp  32771  nlockmgr
 100021    4   udp  32771  nlockmgr
 100005    1   udp    648  mountd
 100005    1   tcp    651  mountd
 100005    2   udp    648  mountd
 100005    2   tcp    651  mountd
 100005    3   udp    648  mountd
 100005    3   tcp    651  mountd
 100024    1   udp    750  status
 100024    1   tcp    753  status
This indicates that nfs (nfsd) and mountd are both running and have registered themselves with the portmapper.

7.5. Troubleshooting the Xserver

Oh boy!, Probably the single most difficult part of setting up an LTSP workstation is getting the X server configured properly. If you are using a fairly new video card, and it is supported by the Xorg Xservers, and you have a fairly new monitor that can handle a large range of frequencies and resolutions, then it is fairly straight forward. Usually, in that case, if it doesn't work, it is most likely the wrong X server for that card.

When an X server doesn't work with your card, it is usually pretty obvious. Either the X server won't start, or the display will be incorrect.

When the workstation is ready to start the X server, it calls the startx script, which starts the X server on the local workstation, with a -query option pointing to a server, where a display manager, such as XDM , GDM or KDM is running.

Because the X server is started by the startx script, which is itself started by the init program, when it fails, init will attempt to run it again. init will continue this loop of trying to run the X server 10 times, then give up, because it thinks that it is re-spawning too quickly. After it finally gives up, the error message from the X server should be left on the screen.

Waiting for the X server to fail 10 times can be rather irritating, so a simple way to avoid the repeated failures is to start the workstation in runlevel 3, so that the X server is NOT started automatically. Instead, when you boot the workstation, you will get a bash prompt. From the bash prompt, you can start the X server manually with the following command:

sh  /tmp/start_ws 
The X server will attempt to start, then when it fails, it will return back to the bash prompt, so you can see what the reason for the failure is.

7.6. Troubleshooting the Display manager

The display manager is the daemon that runs on the server, waiting for an X server to make contact with it. Once contact has been made, it will display a login dialog box on the screen, offering the user a chance to log into the server.

The three most common display managers are:

Most recent GNU/Linux distributions include all three display managers.

7.6.1. Grey screen with large X cursor

This indicates that the X server is running, but it has not been able to make contact with a display manager. Some possible reasons for that are:

  1. The display manager may not be running
  2. On recent versions of Redhat (7.0 and above), the display manager is started from init. In the /etc/inittab file, there is a line that looks like this:

    x:5:respawn:/etc/X11/prefdm -nodaemon 
    The prefdm script will make the determination of which display manager to run.

    The default display manager depends on which packages have been installed. If Gnome is installed, then GDM is the default display manager. If Gnome is not installed, then the prefdm script will check to see if KDE is installed. If it is, then KDM will be the default display manager. If KDE also is not installed, then XDM will be the default display manager.

    Using the netstat command, you should be able to see if there is a display manager running. On the server, run the following command:

    netstat -ap | grep xdmcp 
    You should see results showing that there is a process listening on the xdmcp port (177).
    udp     0   0 *:xdmcp            *:*               1493/gdm 
    This shows clearly that gdm is running with a PID of 1493, and it is listening on the xdmcp port.

    If you see a line like the one shown above, indicating that there is definitely a display manager listening, then you need to make sure that the workstation is sending the XDMCP query to the correct server.

    In the lts.conf file, you can have an entry which specifies the IP address of the server that is running the display manager. the entry is optional, but if present, should look like this:

    XDM_SERVER  = 
    of course, the IP address for your network may be different than the example above.

    If the 'XDM_SERVER' entry is not present, it will then use the value of the 'SERVER' entry, if present. If that is not present, then it will use

    Which ever way it is specified, you just need to make sure that the IP address is actually the correct address of the server running the display manager.

  3. The display manager may be configured to ignore requests from remote hosts.
  4. If you've determined that the display manager is running, then it is possible that it has been configured to ignore XDMCP requests from remote hosts. You will need to check the configuration files of the particular running display manager, to determine if it is configured properly.

  5. If the Display manager is definitely running, and it is listening for requests from remote workstations, it may be a simple problem that the display manager is unable to map the IP address to a hostname. The workstation either needs to be listed in the /etc/hosts file, or it needs to be correctly setup in the DNS tables.

Chapter 8. Kernels

There are a few decisions that need to be made about the kernel that is run on the workstation. You need to decide whether you want to run one of the standard kernels available for download, or build your own. And, you need to decide if you want to display the graphic screen, complete with the progress bar which, which is made possible by the Linux Progress Patch (LPP).

8.1. Standard LTSP supplied kernels

The kernel package that is available with LTSP actually includes two kernels. One has the Linux Progress Patch already applied and configured, and the other does not have the patch applied.

Both of the kernels already have the NFS Swap patch applied.

8.2. Build your own kernel

There are two ways to configure a kernel for LTSP. The default method is to use something called an 'Initial Ram Disk', or initrd for short. The initrd image is a small filesystem that is appended to the kernel. The initrd filesystem image is loaded into memory, and once the kernel is booted, it will mount the ramdisk as its root filesystem. There are a couple of advantages of using an initrd image. First, we can compile the network drivers as modules and load the correct module during boot. This allows a single kernel which will support virtually all network cards. The other advantage is that we can run the DHCP client as a "user-land" program rather than in kernel-space. Running the client in user-land provides better control over the options requested and received from the server. Also, it makes the kernel slightly smaller. The other way to configure the kernel is without the initrd. Building a kernel without an initrd requires that the specific network card driver be statically linked into the kernel, and it also requires that IP-Autoconfig and "Root filesystem on NFS" are set when building the kernel. The advantage of not using an initrd is that the kernel is slightly smaller, and it will boot slightly faster. once the workstation is up and running, there is virtually no difference in how the workstation functions.

The standard kernel for LTSP includes an Initial Ramdisk (initrd) that takes care of detecting the network card, and making a user-space DHCP request. A major goal for the image was to make it as small as possible. So, we chose the uClinux libc replacement library, and busybox for the utilities that we need during the boot.

If you want to build your own kernels, you should download the ltsp_initrd_kit package. It contains the root filesystem hierarchy, and a script for building the image.

8.2.1. Obtaining the source for the kernel

When building a custom kernel, it's usually a good idea to start with fresh kernel sources direct from the site. The reason for this is that the distributions, like Redhat, apply many patches to their kernel sources, leaving you with a set of source code that really doesn't match that of the official kernel.

Download the kernel source package of your choice, and save it in the /usr/src directory. The kernels are located in the /pub/linux/kernel directory of the ftp server. You will need to grab a recent 2.4.x series kernel, because you need to include devfs support.

Also, if you want to include support for swapping over NFS or the Linux Progress Patch (LPP), you will need to make sure that you get the patches and kernel sources that are all the same. At the time of this writing, the 2.4.9 kernel is the latest to support those features.

For our example, we will use the 2.4.9 kernel. The entire path is

Unpack the kernel sources in the /usr/src directory. You need to be careful, because when you un-tar the package, it will be in a directory called linux. You may already have a directory called linux with a different set of source code, and you don't want to clobber it. So, check for an existing directory, and if it is there, rename it to something else before unpacking the sources.

The source package we downloaded had been compressed with the bzip2 compression utility. So, we need to uncompress it before we feed it to the tar program. You can use the following command to unpack it:

bunzip2 <linux-2.4.9.tar.bz2 | tar xf - 
When the unpacking completes, you will have a directory called linux containing the entire source tree. At this point, I usually like to rename the directory to something more meaningful.
mv linux linux-2.4.9 
Once the directory has been renamed, then change into the new directory:
cd linux-2.4.9 

I usually like to modify the Makefile before I start configuring the new kernel. Near the top of the file is a variable named EXTRAVERSION. I set this to 'ltsp-1', so that the actual version number of the kernel will be '2.4.9-ltsp-1', which makes it easier to identify the kernel later. The top of the Makefile should look like this when you are done:



8.2.2. Kernel Patches

After unpacking the kernel, you may have various patches you want to apply. For example, the NFS Swap patch or the Linux Progress Patch. These patches MUST be applied before configuring the kernel. NFS Swap patch

The NFS Swap patch will allow the workstation kernel to use a swapfile located on an NFS server. While it usually recommended to have enough memory in the workstation to not require swapping, it can sometimes be difficult to add more memory, especially on older computers. So, the ability to swap over NFS can make an otherwise unusable computer actually usable.

If the current directory is /usr/src/linux-2.4.9, and the patch is in /usr/src, you can do the following to test the patch:

patch -p1 --dry-run <../linux-2.4.9-nfs-swap.diff 
This will test the patch, to make sure it can be applied cleanly. If it finishes with no errors, then you can apply the patch without the --dry-run option.
patch -p1 <../linux-2.4.9-nfs-swap.diff Linux Progress Patch (LPP)

The Linux Progress Patch (LPP) will allow you to configure a graphic logo to display during the boot process. The normal kernel boot messages are redirected to another tty screen, and special instructions are added to the boot scripts to cause the Progress bar to reflect how far along the boot process is.

Like the NFS Swap patch, you can test the LPP patch by issuing this command:

patch -p1 --dry-run <../lpp-2.4.9 
If the test completes successfully, then you can apply the patch with:
patch -p1 <../lpp-2.4.9 

8.2.3. Configuring kernel options

You can now run the kernel configuration program of your choice. Available choices are: Kernel configuration for use with an initrd

Configuring the kernel for use with an initrd requires the following options to be set:

That should take care of the required options. You can also turn off many features of the kernel, to reduce the size of the kernel. Kernel configuration for use without an initrd

Configuring the kernel for use without an initrd differs from a kernel with an initrd in a few ways:

8.2.4. Building the kernel

To make things easier, a copy of the .config file is included in the ltsp_initrd_kit package. You can copy that to the /usr/src/linux-2.4.9 directory.

Once you are done selecting or de-selecting the kernel options, you need to build the kernel. The following commands need to be executed to build the kernel:

make dep
make clean
make bzImage
make modules
make modules_install 
You can string them all together like this:
make dep && make clean && make bzImage && make modules && make modules_install 
The double ampersand (&) means that if the first command completes successfully, then the second command will be executed. If the second command completes successfully, then the third command will be executed, and so on.

When the kernel compilation is finished, the new kernel will be sitting in /usr/src/linux-2.4.9/arch/i386/boot/bzImage.

8.2.5. Tagging the kernel for Etherboot

For Etherboot to handle a Linux kernel, it needs to be prepared. This is called 'Tagging' the kernel. This process will add some additional code to the kernel that is executed before control is passed to the kernel. The tool for tagging a kernel is called ' mknbi-linux'.

The ltsp_initrd_kit includes a shell script called buildk that includes all of the commands that you need to prepare the kernel image for network booting.

Chapter 9. lts.conf entries

When we designed LTSP, one of the issues that we knew we would have to deal with varying hardware configurations for the workstations. Certainly, whatever combination of processor, network card and video card available today would not be available in 3 months, when we want to add more workstations to the network.

So, we devised a way of specifying the configuration of each workstation. The configuration file is called lts.conf and it lives in the /opt/ltsp/i386/etc directory.

The format of the lts.conf allows for 'default' settings and individual workstation settings. If all of your workstations are identical, you could specify all of the configuration settings in the '[Default]' section.

9.1. Sample lts.conf file

Here is an example of the lts.conf file:

        SERVER             =
        X_MOUSE_PROTOCOL   = "PS/2"
        X_MOUSE_DEVICE     = "/dev/psaux"
        X_MOUSE_RESOLUTION = 400
        X_MOUSE_BUTTONS    = 3
        USE_XFS            = N
        SCREEN_01          = startx

        XSERVER            = auto
        X_MOUSE_PROTOCOL   = "Microsoft"
        X_MOUSE_DEVICE     = "/dev/ttyS1"
        X_MOUSE_BUTTONS    = 3
        X_MOUSE_BAUD       = 1200

        XSERVER            = XF86_Mach64

        SCREEN_01          = shell 

9.2. Available lts.conf parameters

9.2.1. General parameters


Comments start with the hash '#' sign and continue through the end of the line.


This indicates where the LTSP root filesystems are located. The default value is /opt/ltsp


This is the server that is used for the XDM_SERVER, TELNET_HOST, XFS_SERVER and SYSLOG_HOST, if any of those are not specified explicitly. If you have one machine that is acting as the server for everything, then you can just specify the address here and omit the other server parameters. If this value is not set, will be used.


If you want to send logging messages to a machine other than the default server, then you can specify the machine here. If this parameter is NOT specified, then it will use the 'SERVER' parameter described above.


This specifies the IP address of the NFS server used when the /home filesystem is mounted. The default is whatever the SERVER is set to.


Set this to Y if you want to turn on NFS swap. The default is N


This is how you can control the size of the swapfile. The default is 64m.


The swapfile can exist on any server on the network that is capable of handling it. You can specify the IP address of that server. The default is whatever the value of NFS_SERVER set to.


The directory on the server that is being exported via NFS. The default is /var/opt/ltsp/swapfiles. Make sure that the directory is being exported in the /etc/exports file.


If the workstation is setup to have a character based interface, then the value of this parameter will be used as the host to telnet into. If this value is NOT set, then it will use the value of SERVER above.


Used to build the resolv.conf file.


Used to build the resolv.conf file.

SCREEN_01 through SCREEN_12

Up to 12 screen scripts can be specified for a workstation. This will give you up to 12 sessions on the workstation, each accessible by pressing the Ctrl-Alt-F1 through Ctrl-Alt-F12 keys.

SCREEN_01   = startx
SCREEN_02   = shell

Currently, possible values include:

Look in the /opt/ltsp/i386/etc/screen.d directory for more screen scripts, or write your own, and put them there.
MODULE_01 through MODULE_10

Up to 10 kernel modules can be loaded by using these configuration entries. The entire command line that you would use when running insmod can be specified here. For example:

MODULE_01   = uart401.o
MODULE_02   = "sb.o io=0x220 irq=5 dma=1"
MODULE_03   = opl3.o 

If the value of this parameter is an absolute pathname, then insmod will be used to load the module. Otherwise, modprobe will be used.


When the workstation boots, it creates a ramdisk and mounts it on the /tmp directory. You can control the size of the filesystem with this parameter. Specify it in units of kbytes (1024 bytes). To create a ramdisk of 1 megabyte, specify RAMDISK_SIZE = 1024

If you change the size of the ramdisk here, you will also need to change the size of the ramdisk within the kernel. This can be compiled in, or if you are using Etherboot or Netboot, you tell the kernel the ramdisk size when you tag the kernel with mknbi-linux.

The default value for this is 1024 ( 1 mb )

RCFILE_01 through RCFILE_10

Additional RC scripts can be executed by the rc.local script. Just put the script in the /etc/rc.d directory, and specify the name of the script in one of these entries.


If the LTSP Sound package is installed, you need to set this entry to Y and it will execute the rc.sound script to setup the sound card and daemon. The default is N.

9.2.2. X-Windows parameters


If you want to point XDM to a machine other than the default server, then you can specify the server here. If this parameter is NOT specified, then it will use the 'SERVER' parameter described above.


This defines which X server the workstation will run. For PCI and AGP video cards, this parameter should not be required. The rc.local script should be able to auto-detect the card. You can also set this value to auto to indicate that it should attempt to auto-detect the card.

For ISA video cards, or to force a specific X server, you can specify the name of the driver or Xserver in this entry.

If the value begins with XF86_, then XFree86 3.3.6 will be used. Otherwise, 6.7.0 will be used. The default value for this is auto.

X_MODE_0 through X_MODE_2

Up to 3 Modelines or resolutions can be configured for the workstation. This entry can take two different types of values. It can take either a resolution, or a complete modeline.

X_MODE_0 = 800x600


X_MODE_0 = 800x600 60.75 800 864 928 1088 600 616 621 657 -HSync -VSync

If none of the X_MODE_x entries are specified, then it will use the built-in Modelines, and the resolutions of 1024x768, 800x600 and 640x480.

If one or more X_MODE_x entries are specified, they will completely override any built-in Modelines.


Any value that will work for the Pointer Protocol keyword can be put here. Typical values include "Microsoft" and "PS/2". The default value for this is "PS/2".


This is the device node that the mouse is connected to. If it is a serial mouse, this would be a serial port, such as /dev/ttyS0 or /dev/ttyS1. If it is a PS/2 keyboard mouse, this value would be /dev/psaux. The default value for this is /dev/psaux.


This is the 'Resolution' value in the XF86Config file. A typical value for a serial mouse is 50 and a typical value for a PS/2 mouse would be 400 . The default value for this is 400.


This tells the system how many buttons the mouse has. Usually set to 2 or 3. The default value for this is 3.


This tells the X server to emulate a 3-button mouse by accepting a click of both the right and left mouse buttons simultaneously. The default value is N.


For serial mice, this defines the baud rate. The default value for this is 1200.


This is the number of bits to use for the color depth. Possible values are 8, 15, 16, 24 and 32. 8 bits will give 256 colors, 16 will give 65536 colors, 24 will give 16 million colors and 32 bits will give 4.2 billion colors! Not all X servers support all of these values. The default value for this is 16


You have a choice of running the X Font Server (XFS) or reading the fonts through the NFS filesystem. The font server should provide a simple way of keeping all of the fonts in one place, but there has been some problems when the number of workstations grows past about 40. The 2 values for this option are Y and N. The default value is N. If you do want to use a font server, then you can use the XFS_SERVER entry to specify which host will act as the font server.


If you are using an X Font Server to serve fonts, then you can use this entry to specify the IP address of the host that is acting as the font server. If this is not specified, it will use the default server, which is specified with the SERVER entry described above.


This sets the HorizSync configuration parameter. It defaults to "31-62".


This sets the VertRefresh configuration parameter. It defaults to "55-90".


If you want to create your own complete XF86Config file you can do so and place it in the /opt/ltsp/i386/etc directory. Then, whatever you decide to call it needs to be entered as a value for this configuration variable. For example:

XF86CONFIG_FILE = XF86Config.ws004 

9.2.3. Touch screen parameters


If you are connecting a touch screen to the workstation, you can enable it by setting this entry to Y. If enabled, additional configuration entries will configure specific aspects of the touch screen. The default value is N .


A touch screen works like a mouse and usually is interfaced with the workstation through a serial port. You can specify which serial port with this entry. For example, you could set it equal to /dev/ttyS0. There is no default value for this entry.


Calibration entry for an EloTouch touch screen. Defaults to 433.


Calibration entry for an EloTouch touch screen. Defaults to 3588.


Calibration entry for an EloTouch touch screen. Defaults to 569.


Calibration entry for an EloTouch touch screen. Defaults to 3526.


Calibration entry for an EloTouch touch screen. Defaults to 10.


Calibration entry for an EloTouch touch screen. Defaults to 10.

9.2.4. Local apps parameters


If you want the ability to run applications locally on a workstation, set this variable to Y. Several additional steps must be taken on the server to enable local apps. See the 'Local Apps' section in the LTSP manual for more information. The default value is N.


If you do setup LOCAL_APPS, then you need to have an NIS server on the network. The NIS_DOMAIN entry is where you specify the NIS domain name. It needs to match a domain name that has been defined on the NIS server. This is NOT the same thing as an internet DOMAIN. The default value is ltsp.


Set this to the IP address of your NIS server if you don't want it to send a broadcast looking for an NIS server.

9.2.5. Keyboard parameters

All of the keyboard support files are copied into the /opt/ltsp/i386 hierarchy, so configuring international keyboard support is simply a matter of configuring There are several configuration parameters for this.

The values for the above parameters are from the documentation. Whatever is valid for is valid for these parameters.

We would like to add documentation to show what values are needed for each type of international keyboard. If you work with this and can configure your international keyboards, feedback to the ltsp core group would be greatly appreciated.


The default value for this is the word 'default '.


The default value for this is the word 'default '.


The default value for this is 'us(pc101)'.


The default value for this is 'pc101'.


The default value for this is 'us'.

9.2.6. Printer configuration parameters

Up to three printers can be connected to a diskless workstation. A combination of serial and parallel printers can be configured via the following entries in the lts.conf file:


The device name of the first printer. Names such as /dev/lp0, /dev/ttyS0 or /dev/ttyS1 are allowed.


The type of the printer. Valid choices are 'P ' or for Parallel, and 'S' for Serial.


The TCP/IP Port number to use. By default, it will use ' 9100'


If the printer is serial, this is the setting that will select the baud rate. By default, '9600' will be used.


For serial printers, the flow control can be specified. Either ' S' for Software (XON/XOFF) flow control, or 'H ' for Hardware (CTS/RTS) flow control. If neither is specified, ' S' will be used.


For serial printers, the Parity can be specified. The choices are: 'E'-Even, 'O'-Odd or ' N'-None. If not specified, 'N' will be used.


For serial printers, the number of data bits can be specified. The choices are: '5', '6', '7' and '8'. If not specified, '8' will be used.


Second printer device name


Second printer device type


Second printer device TCP/IP port


Second printer baud rate (serial)


Second printer flow control (serial)


Second printer parity (serial)


Second printer data bits (serial)


Third printer device name


Third printer device type


Third printer device TCP/IP port


Third printer baud rate (serial)


Third printer flow control (serial)


Third printer parity (serial)


Third printer data bits (serial)

Chapter 10. Local Applications

In an LTSP environment, you have a choice of running the applications locally on the workstation, or remotely on the server.

By far, the easiest way to setup an LTSP environment is to run the apps on the server. That is, the client application runs on the server, using the servers' CPU and memory, while it displays its output on the workstation and uses the workstations' keyboard and mouse.

This is a fundamental capability of X Windows. The workstation works just like a standard X Windows terminal.

In order for a user to run an application on the workstation, the workstation needs to know some information about the user. Info such as the following:

LTSP relies on the Network Information Service - NIS, (formerly called Yellow Pages) to make the user and group information available to the workstations.

10.1. Benefits of running apps locally

There are benefits to running applications on the workstation.

10.2. Issues with setting up support for local apps

Setting up the ability to run applications locally requires much more.

10.3. Server Configuration for Local Apps

10.3.1. lts.conf entries

A few entries need to be setup in the lts.conf file:


This must be set to Y. It will cause the following to happen during the workstation boot process:

  1. The /home directory on the server will be mounted via NFS.
  2. The /var/yp/nicknames will be created on the workstation.
  3. The portmapper will be started on the workstation.
  4. xinetd will be started on the workstation.
  5. The /etc/yp.conf file will be created on the workstation.
  6. The domainname command will be run with the value of the NIS_DOMAIN lts.conf entry.
  7. The ypbind will be run on the workstation.

With NIS, all of the nodes on the network that want to be associated with a specific NIS server need to belong to the same NIS domain (this is not related in any way to a DNS Domain). You use the NIS_DOMAIN entry to specify the name of the NIS domain that the workstation will belong to.


NIS will either attempt to bind with a specific NIS server, or it will send a broadcast out to the network, looking for a server. If you want to choose a specific server, then enter the IP address of that server in the NIS_SERVER entry.

10.3.2. Network Information Service - NIS

NIS is a Client/Server type of service. On the server, there is a daemon running, that will accept requests from the clients (workstations). The daemon on the server is called ypserv.

On the workstation, there is a process called ypbind. When the workstation needs to lookup information about a user, such as verifying a password or finding the users home directory, it will use ypbind to establish a connection to ypserv, on the server.

If you are already running NIS in your network environment, then there is no need to configure the LTSP server to also run ypserv. You can just configure the NIS_DOMAINNAME and NIS_SERVER entries in lts.conf to match your current NIS scheme.

If you are NOT already running NIS in your network, then you will need to configure the server to run ypserv.

For complete information on setting up an NIS server, refer to the HOWTO document on the LDP site called The Linux NIS(YP)/NYS/NIS+ HOWTO. Refer to the list of other sources of information at the end of this document.

10.4. Application Configuration

To setup an application to run on the workstation, you need to put all of the components of the application in a place where the workstation can see it.

With older versions of LTSP (2.08 and earlier), lots of directories were exported on the server and mounted by the workstation. Directories such as /bin, /usr/bin , /lib and /usr were exposed to the workstation.

The problem with that scheme is that it only works if the workstation and the server are the same architecture. In fact, even differences, like the server being a Pentium II (i686) and the workstation being a classic Pentium (i586) can be a problem, because the server will likely have the i686 libraries and not the i386, i486 or i586 libraries.

So, the cleanest way to handle this is to have a complete tree with all of the binaries and libraries that the workstation will need, independent of the server binaries and libraries.

Configuring an application for local execution requires putting all of the required pieces in the tree. One of the packages available for download from the LTSP site is the Local Netscape package, which installs a number of files into the /opt/ltsp/i386/usr/local/netscape directory. Things like Java classes, help files, executable binary files and scripts are put there.

Netscape doesn't need any additional system libraries, so there is nothing to add to the /opt/ltsp/i386/lib directory. Many applications do require additional libraries.

So, how can you determine what libraries are needed? That's where the ldd command comes in handy.

Lets assume that you want to setup a certain application to run locally. We'll pick gaim as an example. gaim is an AOL Instant Messenger client, that will allow you to communicate with other people on AOL forums.

The first thing you need to do is find the gaim executable binary file. On a Redhat 7.2 system, it is located in the /usr/bin directory.

Once you locate the gaim binary, you can run ldd against it:

[jam@server /]$ ldd /usr/bin/gaim    => /usr/lib/ (0x40033000)            => /lib/i686/ (0x40051000)          => /lib/ (0x40074000)     => /usr/lib/ (0x4008a000)     => /usr/lib/ (0x4015d000)    => /usr/lib/ (0x4016c000)           => /usr/X11R6/lib/ (0x40191000)          => /usr/X11R6/lib/ (0x4019a000)      => /usr/lib/ (0x401b1000)           => /lib/ (0x402df000)      => /usr/lib/ (0x402e3000)  => /usr/lib/ (0x40319000)           => /usr/X11R6/lib/ (0x4031d000)         => /usr/X11R6/lib/ (0x40325000)          => /usr/X11R6/lib/ (0x40333000)       => /usr/lib/ (0x40411000) => /usr/lib/ (0x40429000)          => /usr/lib/ (0x4042e000)           => /usr/lib/ (0x40436000)     => /usr/lib/ (0x40444000)        => /lib/ (0x40468000)            => /lib/i686/ (0x40495000)            => /usr/lib/ (0x405d1000)
        /lib/   => /lib/ (0x40000000) 

The listing above shows all of the libraries that the gaim program is dynamically linked against.

Most programs that use shared libs, rely on the dynamic loader ld-linux to locate and load each of the shared libraries. Some programs, however, load the libraries manually with the dlopen() function call. For those applications, ldd will not show the libraries. In that case, strace can be used to trace the execution of the program, and you will see the dlopen() calls, with the name of the library listed in the arguments.

Once the list of libraries has been collected, the required libraries will need to be copied to the appropriate places in the /opt/ltsp/i386 tree.

10.5. Launching local applications

In X Windows, programs typically run relative to where the window manager runs. That is, if the window manager is running on the server, displaying its output on the workstation, then any programs that are launched, will also run on the server, sending their output to the workstation.

The trick is having the server tell the workstation to launch the program. This is typically done with the rsh command.

Here's an example of how to run the gaim program on the workstation:

HOST=`echo $DISPLAY | awk -F: '{ print $1 }'`
rsh ${HOST} /usr/bin/gaim -display ${DISPLAY} 

The above example can be entered in an xterm window, or it can be put into a shell script, and be launched by an icon on the desktop.

Launching local Netscape is done in a similar way, but an additional environment variable needs to be set, before running the program.

HOST=`echo $DISPLAY | awk -F: '{ print $1 }'`
rsh ${HOST} MOZILLA_HOME=/usr/local/netscape \
       /usr/local/netscape/netscape -display ${DISPLAY} 

Chapter 11. Configuration examples

Almost any aspect of the workstation can be configured with entries in the lts.conf, which is usually located in the /opt/ltsp/i386/etc directory.

11.1. Serial Mouse

Here is an example of the lts.conf entries for a standard 2-button serial mouse:

X_MOUSE_PROTOCOL    = "Microsoft"
X_MOUSE_DEVICE      = "/dev/ttyS0"

11.2. PS/2 Wheel mouse

Here is an example of the lts.conf entries for an Intellimouse:

X_MOUSE_DEVICE      = "/dev/psaux"
X_ZAxisMapping      = "4 5"

11.3. USB printer on a ThinkNic

The ThinkNIC workstation has a USB port, which can be used for attaching a local printer. Here is an example of the entries required in the lts.conf file:

MODULE_01           = usb-ohci
MODULE_02           = printer
PRINTER_0_DEVICE    = /dev/usb/lp0

11.4. Forcing a workstation to load a XFree86 3.3.6 Xserver

By default, 6.7.0 will be used for a workstation. If you want to force the workstation to use an older XFree86 3.3.6 Xserver, you first need to load the proper 3.3.6 Xserver package. Then, you need to add the entry in the lts.conf file. This is an example of specifying the SVGA Xserver:

XSERVER             = XF86_SVGA

Chapter 12. Other sources of information

12.1. Online references

  1. The LTSP home page  

  3. Diskless-Nodes HOW-TO document for Linux  

  5. Etherboot Home Page  

  7. The Rom-O-Matic site  

  9. Mouse Support  

  11. XFree86-Video-Timings-HOWTO  

  13. The Linux NIS(YP)/NYS/NIS+ HOWTO  

12.2. Print publications

  1. Managing NFS and NIS
    Hal Stern
    O'Reilly & Associates, Inc.
    ISBN 0-937175-75-7

  2. TCP/IP Illustrated, Volume 1
    W. Richard Stevens
    ISBN 0-201-63346-9

  3. X Window System Administrator's Guide
    Linda Mui and Eric Pearce
    O'Reilly & Associates, Inc.
    ISBN 0-937175-83-8
    (Volume 8  of the The Definitive Guides to the X Window System)