Petter Reinholdtsen

Idea for storing LTSP configuration in LDAP
11th July 2010

Vagrant mentioned on IRC today that ltsp_config now support sourcing files from /usr/share/ltsp/ltsp_config.d/ on the thin clients, and that this can be used to fetch configuration from LDAP if Debian Edu choose to store configuration there.

Armed with this information, I got inspired and wrote a test module to get configuration from LDAP. The idea is to look up the MAC address of the client in LDAP, and look for attributes on the form ltspconfigsetting=value, and use this to export SETTING=value to the LTSP clients.

The goal is to be able to store the LTSP configuration attributes in a "computer" LDAP object used by both DNS and DHCP, and thus allowing us to store all information about a computer in one place.

This is a untested draft implementation, and I welcome feedback on this approach. A real LDAP schema for the ltspClientAux objectclass need to be written. Comments, suggestions, etc?

# Store in /opt/ltsp/$arch/usr/share/ltsp/ltsp_config.d/ldap-config
# Fetch LTSP client settings from LDAP based on MAC address
# Uses ethernet address as stored in the dhcpHost objectclass using
# the dhcpHWAddress attribute or ethernet address stored in the
# ieee802Device objectclass with the macAddress attribute.
# This module is written to be schema agnostic, and only depend on the
# existence of attribute names.
# The LTSP configuration variables are saved directly using a
# ltspConfig prefix and uppercasing the rest of the attribute name.
# To set the SERVER variable, set the ltspConfigServer attribute.
# Some LDAP schema should be created with all the relevant
# configuration settings.  Something like this should work:
# objectclass ( NAME 'ltspClientAux'
#     SUP top
#     MAY ( ltspConfigServer $ ltsConfigSound $ ... )

if [ "$LDAPSERVER" ] ; then
    LDAPBASE=$(debian-edu-ldapserver -b)
    for MAC in $(LANG=C ifconfig |grep -i hwaddr| awk '{print $5}'|sort -u) ; do
	filter="(|(dhcpHWAddress=ethernet $MAC)(macAddress=$MAC))"
	ldapsearch -h "$LDAPSERVER" -b "$LDAPBASE" -v -x "$filter" | \
	    grep '^ltspConfig' | while read attr value ; do
	    # Remove prefix and convert to upper case
	    attr=$(echo $attr | sed 's/^ltspConfig//i' | tr a-z A-Z)
	    # bass value on to clients
	    eval "$attr=$value; export $attr"

I'm not sure this shell construction will work, because I suspect the while block might end up in a subshell causing the variables set there to not show up in ltsp-config, but if that is the case I am sure the code can be restructured to make sure the variables are passed on. I expect that can be solved with some testing. :)

If you want to help out with implementing this for Debian Edu, please contact us on

Update 2010-07-17: I am aware of another effort to store LTSP configuration in LDAP that was created around year 2000 by PC Xperience, Inc., 2000. I found its files on a personal home page over at

Tags: debian, debian edu, english, ldap, nuug.

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