Petter Reinholdtsen

Autodetecting Client setup for roaming workstations in Debian Edu
7th August 2010

A few days ago, I tried to install a Roaming workation profile from Debian Edu/Squeeze while on the university network here at the University of Oslo, and noticed how much had to change to get it operational using the university infrastructure. It was fairly easy, but it occured to me that Debian Edu would improve a lot if I could get the client to connect without any changes at all, and thus let the client configure itself during installation and first boot to use the infrastructure around it. Now I am a huge step further along that road.

With our current squeeze-test packages, I can select the roaming workstation profile and get a working laptop connecting to the university LDAP server for user and group and our active directory servers for Kerberos authentication. All this without any configuration at all during installation. My users home directory got a bookmark in the KDE menu to mount it via SMB, with the correct URL. In short, openldap and sssd is correctly configured. In addition to this, the client look for http://wpad/wpad.dat to configure a web proxy, and when it fail to find it no proxy settings are stored in /etc/environment and /etc/apt/apt.conf. Iceweasel and KDE is configured to look for the same wpad configuration and also do not use a proxy when at the university network. If the machine is moved to a network with such wpad setup, it would automatically use it when DHCP gave it a IP address.

The LDAP server is located using DNS, by first looking for the DNS entry ldap.$domain. If this do not exist, it look for the _ldap._tcp.$domain SRV records and use the first one as the LDAP server. Next, it connects to the LDAP server and search all namingContexts entries for posixAccount or posixGroup objects, and pick the first one as the LDAP base. For Kerberos, a similar algorithm is used to locate the LDAP server, and the realm is the uppercase version of $domain.

So, what is not working, you might ask. SMB mounting my home directory do not work. No idea why, but suspected the incorrect Kerberos settings in /etc/krb5.conf and /etc/samba/smb.conf might be the cause. These are not properly configured during installation, and had to be hand-edited to get the correct Kerberos realm and server, but SMB mounting still do not work. :(

With this automatic configuration in place, I expect a Debian Edu roaming profile installation would be able to automatically detect and connect to any site using LDAP and Kerberos for NSS directory and PAM authentication. It should also work out of the box in a Active Directory environment providing posixAccount and posixGroup objects with UID and GID values.

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

Tags: debian edu, english, nuug.

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