Petter Reinholdtsen

Recently I have spent some time evaluating the multimedia browser plugins available in Debian Lenny, to see which one we should use by default in Debian Edu. We need an embedded video playing plugin with control buttons to pause or stop the video, and capable of streaming all the multimedia content available on the web. The test results and notes are available on the Debian wiki. I was surprised how few of the plugins are able to fill this need. My personal video player favorite, VLC, has a really bad plugin which fail on a lot of the test pages. A lot of the MIME types I would expect to work with any free software player (like video/ogg), just do not work. And simple formats like the audio/x-mplegurl format (m3u playlists), just isn't supported by the totem and vlc plugins. I hope the situation will improve soon. No wonder sites use the proprietary Adobe flash to play video.

For Lenny, we seem to end up with the mplayer plugin. It seem to be the only one fitting our needs. :/

This weekend we had a small developer gathering for Debian Edu in Oslo. Most of Saturday was used for the general assemly for the member organization, but the rest of the weekend I used to tune the LTSP installation. LTSP now work out of the box on the 10-network. Acer Aspire One proved to be a very nice thin client, with both screen, mouse and keybard in a small box. Was working on getting the diskless workstation setup configured out of the box, but did not finish it before the weekend was up.

Did not find time to look at the 4 VGA cards in one box we got from the Brazilian group, so that will have to wait for the next development gathering. Would love to have the Debian Edu installer automatically detect and configure a multiseat setup when it find one of these cards.

The Norwegian Unix User Group is recording our montly presentation on video, and recently we have worked on improving the quality of the recordings by mixing the slides directly with the video stream. For this, we use the dvswitch package from the Debian video team. As this require quite one computer per video source, and NUUG do not have enough laptops available, we need to borrow laptops. And to avoid having to install extra software on these borrwed laptops, I have wrapped up all the programs needed on a bootable USB stick. The software required is dvswitch with assosiated source, sink and mixer applications and dvgrab. To allow this setup to work without any configuration, I've patched dvswitch to use avahi to connect the various parts together. And to allow us to use laptops without firewire plugs, I upgraded dvgrab to the one from Debian/unstable to get one that work with USB sources. We have not yet tested this setup in a production setup, but I hope it will work properly, and allow us to set up a video mixer in a very short time frame. We will need it for Go Open 2009.

The USB image is for a 1 GB memory stick, but can be used on any larger stick as well.

As part of the work we do in NUUG to publish video recordings of our monthly presentations, we provide a page with embedded video for easy access to the recording. Putting a good set of HTML tags together to get working embedded video in all browsers and across all operating systems is not easy. I hope this will become easier when the <video> tag is implemented in all browsers, but I am not sure. We provide the recordings in several formats, MPEG1, Ogg Theora, H.264 and Quicktime, and want the browser/media plugin to pick one it support and use it to play the recording, using whatever embed mechanism the browser understand. There is at least four different tags to use for this, the new HTML5 <video> tag, the <object> tag, the <embed> tag and the <applet> tag. All of these take a lot of options, and finding the best options is a major challenge.

I just tested the experimental Opera browser available from labs.opera.com, to see how it handled a <video> tag with a few video sources and no extra attributes. I was not very impressed. The browser start by fetching a picture from the video stream. Not sure if it is the first frame, but it is definitely very early in the recording. So far, so good. Next, instead of streaming the 76 MiB video file, it start to download all of it, but do not start to play the video. This mean I have to wait for several minutes for the downloading to finish. When the download is done, the playing of the video do not start! Waiting for the download, but I do not get to see the video? Some testing later, I discover that I have to add the controls="true" attribute to be able to get a play button to pres to start the video. Adding autoplay="true" did not help. I sure hope this is a misfeature of the test version of Opera, and that future implementations of the <video> tag will stream recordings by default, or at least start playing when the download is done.

The test page I used (since changed to add more attributes) is available from the nuug site. Will have to test it with the new Firefox too.

In the test process, I discovered a missing feature. I was unable to find a way to get the URL of the playing video out of Opera, so I am not quite sure it picked the Ogg Theora version of the video. I sure hope it was using the announced Ogg Theora support. :)

At work with the University of Oslo, we have several hundred computers in our computing center. This give us a challenge in tracking the location and cabling of the computers, when they are added, moved and removed. Some times the location register is not updated when a computer is inserted or moved and we then have to search the room for the "missing" computer.

In the last issue of Linux Journal, I came across a project libdmtx to write and read bar code blocks as defined in the The Data Matrix Standard. This is bar codes that can be read with a normal digital camera, for example that on a cell phone, and several such bar codes can be read by libdmtx from one picture. The bar code standard allow up to 2 KiB to be written in the tag. There is another project with a bar code writer written in postscript capable of creating such bar codes, but this was the first time I found a tool to read these bar codes.

It occurred to me that this could be used to tag and track the machines in our computing center. If both racks and computers are tagged this way, we can use a picture of the rack and all its computers to detect the rack location of any computer in that rack. If we do this regularly for the entire room, we will find all locations, and can detect movements and removals.

I decided to test if this would work in practice, and picked a random rack and tagged all the machines with their names. Next, I took pictures with my digital camera, and gave the dmtxread program these JPEG pictures to see how many tags it could read. This worked fairly well. If the pictures was well focused and not taken from the side, all tags in the image could be read. Because of limited space between the racks, I was unable to get a good picture of the entire rack, but could without problem read all tags from a picture covering about half the rack. I had to limit the search time used by dmtxread to 60000 ms to make sure it terminated in a reasonable time frame.

My conclusion is that this could work, and we should probably look at adjusting our computer tagging procedures to use bar codes for easier automatic tracking of computers.

At work, we have a few hundred Linux servers, and with that amount of hardware it is important to keep track of when the hardware support contract expire for each server. We have a machine (and service) register, which until recently did not contain much useful besides the machine room location and contact information for the system owner for each machine. To make it easier for us to track support contract status, I've recently spent time on extending the machine register to include information about when the support contract expire, and to tag machines with expired contracts to make it easy to get a list of such machines. I extended a perl script already being used to import information about machines into the register, to also do some screen scraping off the sites of Dell, HP and IBM (our majority of machines are from these vendors), and automatically check the support status for the relevant machines. This make the support status information easily available and I hope it will make it easier for the computer owner to know when to get new hardware or renew the support contract. The result of this work documented that 27% of the machines in the registry is without a support contract, and made it very easy to find them. 27% might seem like a lot, but I see it more as the case of us using machines a bit longer than the 3 years a normal support contract last, to have test machines and a platform for less important services. After all, the machines without a contract are working fine at the moment and the lack of contract is only a problem if any of them break down. When that happen, we can either fix it using spare parts from other machines or move the service to another old machine.

I believe the code for screen scraping the Dell site was originally written by Trond Hasle Amundsen, and later adjusted by me and Morten Werner Forsbring. The HP scraping was written by me after reading a nice article in ;login: about how to use WWW::Mechanize, and the IBM scraping was written by me based on the Dell code. I know the HTML parsing could be done using nice libraries, but did not want to introduce more dependencies. This is the current incarnation:

use LWP::Simple;
use POSIX;
use WWW::Mechanize;
use Date::Parse;
[...]
sub get_support_info {
    my ($machine, $model, $serial, $productnumber) = @_;
    my $str;

    if ( $model =~ m/^Dell / ) {
        # fetch website from Dell support
        my $url = "http://support.euro.dell.com/support/topics/topic.aspx/emea/shared/support/my_systems_info/no/details?c=no&cs=nodhs1&l=no&s=dhs&ServiceTag=$serial";
        my $webpage = get($url);
        return undef unless ($webpage);

        my $daysleft = -1;
        my @lines = split(/\n/, $webpage);
        foreach my $line (@lines) {
            next unless ($line =~ m/Beskrivelse/);
            $line =~ s/<[^>]+?>/;/gm;
            $line =~ s/^.+?;(Beskrivelse;)/$1/;

            my @f = split(/\;/, $line);
            @f = @f[13 .. $#f];
            my $lastend = "";
            while ($f[3] eq "DELL") {
                my ($type, $startstr, $endstr, $days) = @f[0, 5, 7, 10];

                my $start = POSIX::strftime("%Y-%m-%d",
                                            localtime(str2time($startstr)));
                my $end = POSIX::strftime("%Y-%m-%d",
                                          localtime(str2time($endstr)));
                $str .= "$type $start -> $end ";
                @f = @f[14 .. $#f];
                $lastend = $end if ($end gt $lastend);
            }
            my $today = POSIX::strftime("%Y-%m-%d", localtime(time));
            tag_machine_unsupported($machine)
                if ($lastend lt $today);
        }
    } elsif ( $model =~ m/^HP / ) {
        my $mech = WWW::Mechanize->new();
        my $url =
            'http://www1.itrc.hp.com/service/ewarranty/warrantyInput.do';
        $mech->get($url);
        my $fields = {
            'BODServiceID' => 'NA',
            'RegisteredPurchaseDate' => '',
            'country' => 'NO',
            'productNumber' => $productnumber,
            'serialNumber1' => $serial,
        };
        $mech->submit_form( form_number => 2,
                            fields      => $fields );
        # Next step is screen scraping
        my $content = $mech->content();

        $content =~ s/<[^>]+?>/;/gm;
        $content =~ s/\s+/ /gm;
        $content =~ s/;\s*;/;;/gm;
        $content =~ s/;[\s;]+/;/gm;

        my $today = POSIX::strftime("%Y-%m-%d", localtime(time));

        while ($content =~ m/;Warranty Type;/) {
            my ($type, $status, $startstr, $stopstr) = $content =~
                m/;Warranty Type;([^;]+);.+?;Status;(\w+);Start Date;([^;]+);End Date;([^;]+);/;
            $content =~ s/^.+?;Warranty Type;//;
            my $start = POSIX::strftime("%Y-%m-%d",
                                        localtime(str2time($startstr)));
            my $end = POSIX::strftime("%Y-%m-%d",
                                      localtime(str2time($stopstr)));

            $str .= "$type ($status) $start -> $end ";

            tag_machine_unsupported($machine)
                if ($end lt $today);
        }
    } elsif ( $model =~ m/^IBM / ) {
        # This code ignore extended support contracts.
        my ($producttype) = $model =~ m/.*-\[(.{4}).+\]-/;
        if ($producttype && $serial) {
            my $content =
                get("http://www-947.ibm.com/systems/support/supportsite.wss/warranty?action=warranty&brandind=5000008&Submit=Submit&type=$producttype&serial=$serial");
            if ($content) {
                $content =~ s/<[^>]+?>/;/gm;
                $content =~ s/\s+/ /gm;
                $content =~ s/;\s*;/;;/gm;
                $content =~ s/;[\s;]+/;/gm;

                $content =~ s/^.+?;Warranty status;//;
                my ($status, $end) = $content =~ m/;Warranty status;([^;]+)\s*;Expiration date;(\S+) ;/;

                $str .= "($status) -> $end ";

                my $today = POSIX::strftime("%Y-%m-%d", localtime(time));
                tag_machine_unsupported($machine)
                    if ($end lt $today);
            }
        }
    }
    return $str;
}

Here are some examples on how to use the function, using fake serial numbers. The information passed in as arguments are fetched from dmidecode.

print get_support_info("hp.host", "HP ProLiant BL460c G1", "1234567890"
                       "447707-B21");
print get_support_info("dell.host", "Dell Inc. PowerEdge 2950", "1234567");
print get_support_info("ibm.host", "IBM eserver xSeries 345 -[867061X]-",
                       "1234567");

I would recommend this approach for tracking support contracts for everyone with more than a few computers to administer. :)

Update 2009-03-06: The IBM page do not include extended support contracts, so it is useless in that case. The original Dell code do not handle extended support contracts either, but has been updated to do so.

The state of standardized LDAP schemas on Linux is far from optimal. There is RFC 2307 documenting one way to store NIS maps in LDAP, and a modified version of this normally called RFC 2307bis, with some modifications to be compatible with Active Directory. The RFC specification handle the content of a lot of system databases, but do not handle DNS zones and DHCP configuration.

In Debian Edu/Skolelinux, we would like to store information about users, SMB clients/hosts, filegroups, netgroups (users and hosts), DHCP and DNS configuration, and LTSP configuration in LDAP. These objects have a lot in common, but with the current LDAP schemas it is not possible to have one object per entity. For example, one need to have at least three LDAP objects for a given computer, one with the SMB related stuff, one with DNS information and another with DHCP information. The schemas provided for DNS and DHCP are impossible to combine into one LDAP object. In addition, it is impossible to implement quick queries for netgroup membership, because of the way NIS triples are implemented. It just do not scale. I believe it is time for a few RFC specifications to cleam up this mess.

I would like to have one LDAP object representing each computer in the network, and this object can then keep the SMB (ie host key), DHCP (mac address/name) and DNS (name/IP address) settings in one place. It need to be efficently stored to make sure it scale well.

I would also like to have a quick way to map from a user or computer and to the net group this user or computer is a member.

Active Directory have done a better job than unix heads like myself in this regard, and the unix side need to catch up. Time to start a new IETF work group?

I'm sitting on the train going home from this weekends Debian Edu/Skolelinux development gathering. I got a bit done tuning the desktop, and looked into the dynamic service location protocol implementation avahi. It look like it could be useful for us. Almost 30 people participated, and I believe it was a great environment to get to know the Skolelinux system. Walter Bender, involved in the development of the Sugar educational platform, presented his stuff and also helped me improve my OLPC installation. He also showed me that his Turtle Art application can be used in standalone mode, and we agreed that I would help getting it packaged for Debian. As a standalone application it would be great for Debian Edu. We also tried to get the video conferencing working with two OLPCs, but that proved to be too hard for us. The application seem to need more work before it is ready for me. I look forward to getting home and relax now. :)

Where I work at the University of Oslo, one decision stand out as a very good one to form a long lived computer infrastructure. It is the simple one, lost by many in todays computer industry: Standardize on open network protocols and open exchange/storage formats, not applications. Applications come and go, while protocols and files tend to stay, and thus one want to make it easy to change application and vendor, while avoiding conversion costs and locking users to a specific platform or application.

This approach make it possible to replace the client applications independently of the server applications. One can even allow users to use several different applications as long as they handle the selected protocol and format. In the normal case, only one client application is recommended and users only get help if they choose to use this application, but those that want to deviate from the easy path are not blocked from doing so.

It also allow us to replace the server side without forcing the users to replace their applications, and thus allow us to select the best server implementation at any moment, when scale and resouce requirements change.

I strongly recommend standardizing - on open network protocols and open formats, but I would never recommend standardizing on a single application that do not use open network protocol or open formats.

One think I have wanted to figure out for a along time is how to run vlc from cron to do recording of video streams on the net. The task is trivial with mplayer, but I do not really trust the security of mplayer (it crashes too often on strange input), and thus prefer vlc. I finally found a way to do it today. I spent an hour or so searching the web for recipes and reading the documentation. The hardest part was to get rid of the GUI window, but after finding the dummy interface, the command line finally presented itself:

URL=http://www.ping.uio.no/video/rms-oslo_2009.ogg
SAVEFILE=rms.ogg
DISPLAY= vlc -q $URL \
  --sout="#duplicate{dst=std{access=file,url='$SAVEFILE'},dst=nodisplay}" \
  --intf=dummy

The command stream the URL and store it in the SAVEFILE by duplicating the output stream to "nodisplay" and the file, using the dummy interface. The dummy interface and the nodisplay output make sure no X interface is needed.

The cron job then need to start this job with the appropriate URL and file name to save, sleep for the duration wanted, and then kill the vlc process with SIGTERM. Here is a complete script vlc-record to use from at or cron:

#!/bin/sh
set -e
URL="$1"
SAVEFILE="$2"
DURATION="$3"
DISPLAY= vlc -q "$URL" \
  --sout="#duplicate{dst=std{access=file,url='$SAVEFILE'},dst=nodisplay}" \
  --intf=dummy < /dev/null > /dev/null 2>&1 &
pid=$!
sleep $DURATION
kill $pid
wait $pid

Julien Blache claim that no patch is better than a useless patch. I completely disagree, as a patch allow one to discuss a concrete and proposed solution, and also prove that the issue at hand is important enough for someone to spent time on fixing it. No patch do not provide any of these positive properties.

There are two software projects that have had huge influence on the quality of free software, and I wanted to mention both in case someone do not yet know them.

The first one is valgrind, a tool to detect and expose errors in the memory handling of programs. It is easy to use, all one need to do is to run 'valgrind program', and it will report any problems on stdout. It is even better if the program include debug information. With debug information, it is able to report the source file name and line number where the problem occurs. It can report things like 'reading past memory block in file X line N, the memory block was allocated in file Y, line M', and 'using uninitialised value in control logic'. This tool has made it trivial to investigate reproducible crash bugs in programs, and have reduced the number of this kind of bugs in free software a lot.

The second one is Coverity which is a source code checker. It is able to process the source of a program and find problems in the logic without running the program. It started out as the Stanford Checker and became well known when it was used to find bugs in the Linux kernel. It is now a commercial tool and the company behind it is running a community service for the free software community, where a lot of free software projects get their source checked for free. Several thousand defects have been found and fixed so far. It can find errors like 'lock L taken in file X line N is never released if exiting in line M', or 'the code in file Y lines O to P can never be executed'. The projects included in the community service project have managed to get rid of a lot of reliability problems thanks to Coverity.

I believe tools like this, that are able to automatically find errors in the source, are vital to improve the quality of software and make sure we can get rid of the crashing and failing software we are surrounded by today.

I spent Monday and tuesday this week in London with a lot of the people involved in the boot system on Debian and Ubuntu, to see if we could find more ways to speed up the boot system. This was an Ubuntu funded developer gathering. It was quite productive. We also discussed the future of boot systems, and ways to handle the increasing number of boot issues introduced by the Linux kernel becoming more and more asynchronous and event base. The Ubuntu approach using udev and upstart might be a good way forward. Time will show.

Anyway, there are a few ways at the moment to speed up the boot process in Debian. All of these should be applied to get a quick boot:

• Use dash as /bin/sh.
• Disable the init.d/hwclock*.sh scripts and make sure the hardware clock is in UTC.
• Install and activate the insserv package to enable dependency based boot sequencing, and enable concurrent booting.

These points are based on the Google summer of code work done by Carlos Villegas.

Support for makefile-style concurrency during boot was uploaded to unstable yesterday. When we tested it, we were able to cut 6 seconds from the boot sequence. It depend on very correct dependency declaration in all init.d scripts, so I expect us to find edge cases where the dependences in some scripts are slightly wrong when we start using this.

On our IRC channel for this effort, #pkg-sysvinit, a new idea was introduced by Raphael Geissert today, one that could affect the startup speed as well. Instead of starting some scripts concurrently from rcS.d/ and another set of scripts from rc2.d/, it would be possible to run a of them in the same process. A quick way to test this would be to enable insserv and run 'mv /etc/rc2.d/S* /etc/rcS.d/; insserv'. Will need to test if that work. :)

After several years of frustration with the lack of activity from the existing sysvinit upstream developer, I decided a few weeks ago to take over the package and become the new upstream. The number of patches to track for the Debian package was becoming a burden, and the lack of synchronization between the distribution made it hard to keep the package up to date.

On the new sysvinit team is the SuSe maintainer Dr. Werner Fink, and my Debian co-maintainer Kel Modderman. About 10 days ago, I made a new upstream tarball with version number 2.87dsf (for Debian, SuSe and Fedora), based on the patches currently in use in these distributions. We Debian maintainers plan to move to this tarball as the new upstream as soon as we find time to do the merge. Since the new tarball was created, we agreed with Werner at SuSe to make a new upstream project at Savannah, and continue development there. The project is registered and currently waiting for approval by the Savannah administrators, and as soon as it is approved, we will import the old versions from svn and continue working on the future release.

It is a bit ironic that this is done now, when some of the involved distributions are moving to upstart as a syvinit replacement.

Since this evening, with the upload of sysvinit version 2.87dsf-2, and the upload of insserv version 1.12.0-10 yesterday, Debian unstable have been migrated to using dependency based boot sequencing. This conclude work me and others have been doing for the last three days. It feels great to see this finally part of the default Debian installation. Now we just need to weed out the last few problems that are bound to show up, to get everything ready for Squeeze.

The next step is migrating /sbin/init from sysvinit to upstart, and fixing the more fundamental problem of handing the event based non-predictable kernel in the early boot.

According to a blog post from Torsten Werner, the current defect report for ISO 29500 (ISO OOXML) is 809 pages. His interesting point is that the defect report is 71 pages more than the full ODF 1.1 specification. Personally I find it more interesting that ISO still believe ISO OOXML can be fixed in ISO. Personally, I believe it is broken beyon repair, and I completely lack any trust in ISO for being able to get anywhere close to solving the problems. I was part of the Norwegian committee involved in the OOXML fast track process, and was not impressed with Standard Norway and ISO in how they handled it.

These days I focus on ODF instead, which seem like a specification with the future ahead of it. We are working in NUUG to organise a ODF seminar this autumn.

Just for fun, I did a search right now on Google for a few file ODF and MS Office based formats (not to be mistaken for ISO or ECMA OOXML), to get an idea of their relative usage. I searched using 'filetype:odt' and equvalent terms, and got these results:

Type	ODF	MS Office
Tekst	odt:282000	docx:308000
Presentasjon	odp:75600	pptx:183000
Regneark	ods:26500	xlsx:145000

Next, I added a 'site:no' limit to get the numbers for Norway, and got these numbers:

Type	ODF	MS Office
Tekst	odt:2480	docx:4460
Presentasjon	odp:299	pptx:741
Regneark	ods:187	xlsx:372

I wonder how these numbers change over time.

I am aware of Google returning different results and numbers based on where the search is done, so I guess these numbers will differ if they are conduced in another country. Because of this, I did the same search from a machine in California, USA, a few minutes after the search done from a machine here in Norway.

Type	ODF	MS Office
Tekst	odt:129000	docx:308000
Presentasjon	odp:44200	pptx:93900
Regneark	ods:26500	xlsx:82400

And with 'site:no':

Type	ODF	MS Office
Tekst	odt:2480	docx:3410
Presentasjon	odp:175	pptx:604
Regneark	ods:186	xlsx:296

Interesting difference, not sure what to conclude from these numbers.

One of the new features in the next Debian/Lenny based release of Debian Edu/Skolelinux, which is scheduled for release in the next few days, is automatic configuration of the service monitoring system Nagios. The previous release had automatic configuration of trend analysis using Munin, and this Lenny based release take that a step further.

When installing a Debian Edu Main-server, it is automatically configured as a Munin and Nagios server. In addition, it is configured to be a server for the SiteSummary system I have written for use in Debian Edu. The SiteSummary system is inspired by a system used by the University of Oslo where I work. In short, the system provide a centralised collector of information about the computers on the network, and a client on each computer submitting information to this collector. This allow for automatic information on which packages are installed on each machine, which kernel the machines are using, what kind of configuration the packages got etc. This also allow us to automatically generate Munin and Nagios configuration.

All computers reporting to the sitesummary collector with the munin-node package installed is automatically enabled as a Munin client and graphs from the statistics collected from that machine show up automatically on http://www/munin/ on the Main-server.

All non-laptop computers reporting to the sitesummary collector are automatically monitored for network presence (ping and any network services detected). In addition, all computers (also laptops) with the nagios-nrpe-server package installed and configured the way sitesummary would configure it, are monitored for full disks, software raid status, swap free and other checks that need to run locally on the machine.

The result is that the administrator on a school using Debian Edu based on Lenny will be able to check the health of his installation with one look at the Nagios settings, without having to spend any time keeping the Nagios configuration up-to-date.

The only configuration one need to do to get Nagios up and running is to set the password used to get access via HTTP. The system administrator need to run "htpasswd /etc/nagios3/htpasswd.users nagiosadmin" to create a nagiosadmin user and set a password for it to be able to log into the Nagios web pages. After that, everything is taken care of.

On Tuesday, the Debian/Lenny based version of Skolelinux was finally shipped. This was a major leap forward for the project, and I am very pleased that we finally got the release wrapped up. Work on the first point release starts imediately, as we plan to get that one out a month after the major release, to include all fixes for bugs we found and fixed too late in the release process to include last Tuesday.

Perhaps it even is time for some partying?

After this first point release, my plan is to focus again on the next major release, based on Squeeze. We will try to get as many of the fixes we need into the official Debian packages before the freeze, and have just a few weeks or months to make it happen.

6 years ago, as part of the Debian Edu development I am involved in, I asked for a hook in the kdm and gdm setup to run scripts as root when the user log out. A bug was submitted against the xfree86-common package in 2004 (#230422), and revisited every time Debian Edu was working on a new release. Today, this finally paid off.

The framework for this feature was today commited to the git repositry for the xorg package, and the git repository for xdm has been updated to use this framework. Next on my agenda is to make sure kdm and gdm also add code to use this framework.

In Debian Edu, we want to ability to run commands as root when the user log out, to get rid of runaway processes and do general cleanup after a user. With this framework in place, we finally can do that in a generic way that work with all display managers using this framework. My goal is to get all display managers in Debian use it, similar to how they use the Xsession.d framework today.

Yesterdays NUUG presentation about Kerberos was inspiring, and reminded me about the need to start using Kerberos in Skolelinux. Setting up a Kerberos server seem to be straight forward, and if we get this in place a long time before the Squeeze version of Debian freezes, we have a chance to migrate Skolelinux away from NFSv3 for the home directories, and over to an architecture where the infrastructure do not have to trust IP addresses and machines, and instead can trust users and cryptographic keys instead.

A challenge will be integration and administration. Is there a Kerberos implementation for Debian where one can control the administration access in Kerberos using LDAP groups? With it, the school administration will have to maintain access control using flat files on the main server, which give a huge potential for errors.

A related question I would like to know is how well Kerberos and pam-ccreds (offline password check) work together. Anyone know?

Next step will be to use Kerberos for access control in Lwat and Nagios. I have no idea how much work that will be to implement. We would also need to document how to integrate with Windows AD, as such shared network will require two Kerberos realms that need to cooperate to work properly.

I believe a good start would be to start using Kerberos on the skolelinux.no machines, and this way get ourselves experience with configuration and integration. A natural starting point would be setting up ldap.skolelinux.no as the Kerberos server, and migrate the rest of the machines from PAM via LDAP to PAM via Kerberos one at the time.

If you would like to contribute to get this working in Skolelinux, I recommend you to see the video recording from yesterdays NUUG presentation, and start using Kerberos at home. The video show show up in a few days.

The last few weeks i have had the pleasure of reading a thought-provoking collection of essays by Cory Doctorow, on topics touching copyright, virtual worlds, the future of man when the conscience mind can be duplicated into a computer and many more. The book titled "Content: Selected Essays on Technology, Creativity, Copyright, and the Future of the Future" is available with few restrictions on the web, for example from his own site. I read the epub-version from feedbooks using fbreader and my N810. I strongly recommend this book.

For some years now, I have wondered how we should handle laptops in Debian Edu. The Debian Edu infrastructure is mostly designed to handle stationary computers, and less suited for computers that come and go.

Now I finally believe I have an sensible idea on how to adjust Debian Edu for laptops, by introducing a new profile for them, for example called Roaming Workstations. Here are my thought on this. The setup would consist of the following:

• During installation, the user name of the owner / primary user of the laptop is requested and a local home directory is set up for the user, with uid and gid information fetched from the LDAP server. This allow the user to work also when offline. The central home directory can be available in a subdirectory on request, for example mounted via CIFS. It could be mounted automatically when a user log in while on the Debian Edu network, and unmounted when the machine is taken away (network down, hibernate, etc), it can be set up to do automatic mounting on request (using autofs), or perhaps some GUI button on the desktop can be used to access it when needed. Perhaps it is enough to use the fish protocol in KDE?
• Password checking is set up to use LDAP or Kerberos authentication when the machine is on the Debian Edu network, and to cache the password for offline checking when the machine unable to reach the LDAP or Kerberos server. This can be done using libpam-ccreds or the Fedora developed System Security Services Daemon packages.
• File synchronisation with the central home directory is set up using a shared directory in both the local and the central home directory, using unison.
• Printing should be set up to print to all printers broadcasting their existence on the local network, and should then work out of the box with CUPS. For sites needing accurate printer quotas, some system with Kerberos authentication or printing via ssh could be implemented.
• For users that should have local root access to their laptop, sudo should be used to allow this to the local user.
• It would be nice if user and group information from LDAP is cached on the client, but given that there are entries for the local user and primary group in /etc/, it should not be needed.

I believe all the pieces to implement this are in Debian/testing at the moment. If we work quickly, we should be able to get this ready in time for the Squeeze release to freeze. Some of the pieces need tweaking, like libpam-ccreds should get support for pam-auth-update (#566718) and nslcd (or perhaps debian-edu-config) should get some integration code to stop its daemon when the LDAP server is unavailable to avoid long timeouts when disconnected from the net. If we get Kerberos enabled, we need to make sure we avoid long timeouts there too.

If you want to help out with implementing this for Debian Edu, please contact us on debian-edu@lists.debian.org.

One interesting feature in Active Directory, is the ability to create a new user with an expired password, and thus force the user to change the password on the first login attempt.

I'm not quite sure how to do that with the LDAP setup in Debian Edu, but did some initial testing with a local account. The account and password aging information is available in /etc/shadow, but unfortunately, it is not possible to specify an expiration time for passwords, only a maximum age for passwords.

A freshly created account (using adduser test) will have these settings in /etc/shadow:

root@tjener:~# chage -l test
Last password change                                    : May 02, 2010
Password expires                                        : never
Password inactive                                       : never
Account expires                                         : never
Minimum number of days between password change          : 0
Maximum number of days between password change          : 99999
Number of days of warning before password expires       : 7
root@tjener:~#

The only way I could come up with to create a user with an expired account, is to change the date of the last password change to the lowest value possible (January 1th 1970), and the maximum password age to the difference in days between that date and today. To make it simple, I went for 30 years (30 * 365 = 10950) and January 2th (to avoid testing if 0 is a valid value).

After using these commands to set it up, it seem to work as intended:

root@tjener:~# chage -d 1 test; chage -M 10950 test
root@tjener:~# chage -l test
Last password change                                    : Jan 02, 1970
Password expires                                        : never
Password inactive                                       : never
Account expires                                         : never
Minimum number of days between password change          : 0
Maximum number of days between password change          : 10950
Number of days of warning before password expires       : 7
root@tjener:~#  

So far I have tested this with ssh and console, and kdm (in Squeeze) login, and all ask for a new password before login in the user (with ssh, I was thrown out and had to log in again).

Perhaps we should set up something similar for Debian Edu, to make sure only the user itself have the account password?

If you want to comment on or help out with implementing this for Debian Edu, please contact us on debian-edu@lists.debian.org.

Update 2010-05-02 17:20: Paul Tötterman tells me on IRC that the shadow(8) page in Debian/testing now state that setting the date of last password change to zero (0) will force the password to be changed on the first login. This was not mentioned in the manual in Lenny, so I did not notice this in my initial testing. I have tested it on Squeeze, and 'chage -d 0 username' do work there. I have not tested it on Lenny yet.

Update 2010-05-02-19:05: Jim Paris tells me via email that an equivalent command to expire a password is 'passwd -e username', which insert zero into the date of the last password change.

These days, the init.d script dependencies in Squeeze are quite complete, so complete that it is actually possible to run all the init.d scripts in parallell based on these dependencies. If you want to test your Squeeze system, make sure dependency based boot sequencing is enabled, and add this line to /etc/default/rcS:

CONCURRENCY=makefile

That is it. It will cause sysv-rc to use the startpar tool to run scripts in parallel using the dependency information stored in /etc/init.d/.depend.boot, /etc/init.d/.depend.start and /etc/init.d/.depend.stop to order the scripts. Startpar is configured to try to start the kdm and gdm scripts as early as possible, and will start the facilities required by kdm or gdm as early as possible to make this happen.

Give it a try, and see if you like the result. If some services fail to start properly, it is most likely because they have incomplete init.d script dependencies in their startup script (or some of their dependent scripts have incomplete dependencies). Report bugs and get the package maintainers to fix it. :)

Running scripts in parallel could be the default in Debian when we manage to get the init.d script dependencies complete and correct. I expect we will get there in Squeeze+1, if we get manage to test and fix the remaining issues.

If you report any problems with dependencies in init.d scripts to the BTS, please usertag the report to get it to show up at the list of usertagged bugs related to this.

The last few days a new boot system called systemd has been introduced to the free software world. I have not yet had time to play around with it, but it seem to be a very interesting alternative to upstart, and might prove to be a good alternative for Debian when we are able to switch to an event based boot system. Tollef is in the process of getting systemd into Debian, and I look forward to seeing how well it work. I like the fact that systemd handles init.d scripts with dependency information natively, allowing them to run in parallel where upstart at the moment do not.

Unfortunately do systemd have the same problem as upstart regarding platform support. It only work on recent Linux kernels, and also need some new kernel features enabled to function properly. This means kFreeBSD and Hurd ports of Debian will need a port or a different boot system. Not sure how that will be handled if systemd proves to be the way forward.

In the mean time, based on the input on debian-devel@ regarding parallel booting in Debian, I have decided to enable full parallel booting as the default in Debian as soon as possible (probably this weekend or early next week), to see if there are any remaining serious bugs in the init.d dependencies. A new version of the sysvinit package implementing this change is already in experimental. If all go well, Squeeze will be released with parallel booting enabled by default.

In the recent Debian Edu versions, the sitesummary system is used to keep track of the machines in the school network. Each machine will automatically report its status to the central server after boot and once per night. The network setup is also reported, and using this information it is possible to get the MAC address of all network interfaces in the machines. This is useful to update the DHCP configuration.

To give some idea how to use sitesummary, here is a one-liner to ist all MAC addresses of all machines reporting to sitesummary. Run this on the collector host:

perl -MSiteSummary -e 'for_all_hosts(sub { print join(" ", get_macaddresses(shift)), "\n"; });'

This will list all MAC addresses assosiated with all machine, one line per machine and with space between the MAC addresses.

To allow system administrators easier job at adding static DHCP addresses for hosts, it would be possible to extend this to fetch machine information from sitesummary and update the DHCP and DNS tables in LDAP using this information. Such tool is unfortunately not written yet.

Since this evening, parallel booting is the default in Debian/unstable for machines using dependency based boot sequencing. Apparently the testing of concurrent booting has been wider than expected, if I am to believe the input on debian-devel@, and I concluded a few days ago to move forward with the feature this weekend, to give us some time to detect any remaining problems before Squeeze is frozen. If serious problems are detected, it is simple to change the default back to sequential boot. The upload of the new sysvinit package also activate a new upstream version.

More information about dependency based boot sequencing is available from the Debian wiki. It is currently possible to disable parallel booting when one run into problems caused by it, by adding this line to /etc/default/rcS:

CONCURRENCY=none

If you report any problems with dependencies in init.d scripts to the BTS, please usertag the report to get it to show up at the list of usertagged bugs related to this.

Today, the last piece of the puzzle for roaming laptops in Debian Edu finally entered the Debian archive. Today, the new libpam-mklocaluser package was accepted. Two days ago, two other pieces was accepted into unstable. The pam-python package needed by libpam-mklocaluser, and the sssd package passed NEW on Monday. In addition, the libpam-ccreds package we need is in experimental (version 10-4) since Saturday, and hopefully will be moved to unstable soon.

This collection of packages allow for two different setups for roaming laptops. The traditional setup would be using libpam-ccreds, nscd and libpam-mklocaluser with LDAP or Kerberos authentication, which should work out of the box if the configuration changes proposed for nscd in BTS report #485282 is implemented. The alternative setup is to use sssd with libpam-mklocaluser to connect to LDAP or Kerberos and let sssd take care of the caching of passwords and group information.

I have so far been unable to get sssd to work with the LDAP server at the University, but suspect the issue is some SSL/GnuTLS related problem with the server certificate. I plan to update the Debian package to version 1.2, which is scheduled for next week, and hope to find time to make sure the next release will include both the Debian/Ubuntu specific patches. Upstream is friendly and responsive, and I am sure we will find a good solution.

The idea is to set up the roaming laptops to authenticate using LDAP or Kerberos and create a local user with home directory in /home/ when a usre in LDAP logs in via KDM or GDM for the first time, and cache the password for offline checking, as well as caching group memberhips and other relevant LDAP information. The libpam-mklocaluser package was created to make sure the local home directory is in /home/, instead of /site/server/directory/ which would be the home directory if pam_mkhomedir was used. To avoid confusion with support requests and configuration, we do not want local laptops to have users in a path that is used for the same users home directory on the home directory servers.

One annoying problem with gdm is that it do not show the PAM message passed to the user from libpam-mklocaluser when the local user is created. Instead gdm simply reject the login with some generic message. The message is shown in kdm, ssh and login, so I guess it is a bug in gdm. Have not investigated if there is some other message type that can be used instead to get gdm to also show the message.

If you want to help out with implementing this for Debian Edu, please contact us on debian-edu@lists.debian.org.

After a long break from debian-installer development, I finally found time today to return to the project. Having to spend less time working dependency based boot in debian, as it is almost complete now, definitely helped freeing some time.

A while back, I ran into a problem while working on Debian Edu. We include some firmware packages on the Debian Edu CDs, those needed to get disk and network controllers working. Without having these firmware packages available during installation, it is impossible to install Debian Edu on the given machine, and because our target group are non-technical people, asking them to provide firmware packages on an external medium is a support pain. Initially, I expected it to be enough to include the firmware packages on the CD to get debian-installer to find and use them. This proved to be wrong. Next, I hoped it was enough to symlink the relevant firmware packages to some useful location on the CD (tried /cdrom/ and /cdrom/firmware/). This also proved to not work, and at this point I found time to look at the debian-installer code to figure out what was going to work.

The firmware loading code is in the hw-detect package, and a closer look revealed that it would only look for firmware packages outside the installation media, so the CD was never checked for firmware packages. It would only check USB sticks, floppies and other "external" media devices. Today I changed it to also look in the /cdrom/firmware/ directory on the mounted CD or DVD, which should solve the problem I ran into with Debian edu. I also changed it to look in /firmware/, to make sure the installer also find firmware provided in the initrd when booting the installer via PXE, to allow us to provide the same feature in the PXE setup included in Debian Edu.

To make sure firmware deb packages with a license questions are not activated without asking if the license is accepted, I extended hw-detect to look for preinst scripts in the firmware packages, and run these before activating the firmware during installation. The license question is asked using debconf in the preinst, so this should solve the issue for the firmware packages I have looked at so far.

If you want to discuss the details of these features, please contact us on debian-boot@lists.debian.org.

A few days ago, parallel booting was enabled in Debian/testing. The feature seem to hold up pretty well, but three fairly serious issues are known and should be solved:

• The wicd package seen to break NFS mounting and network setup when parallel booting is enabled. No idea why, but the wicd maintainer seem to be on the case.
• The nvidia X driver seem to have a race condition triggered more easily when parallel booting is in effect. The maintainer is on the case.
• The sysv-rc package fail to properly enable dependency based boot sequencing (the shutdown is broken) when old file-rc users try to switch back to sysv-rc. One way to solve it would be for file-rc to create /etc/init.d/.legacy-bootordering, and another is to try to make sysv-rc more robust. Will investigate some more and probably upload a workaround in sysv-rc to help those trying to move from file-rc to sysv-rc get a working shutdown.

All in all not many surprising issues, and all of them seem solvable before Squeeze is released. In addition to these there are some packages with bugs in their dependencies and run level settings, which I expect will be fixed in a reasonable time span.

If you report any problems with dependencies in init.d scripts to the BTS, please usertag the report to get it to show up at the list of usertagged bugs related to this.

Update: Correct bug number to file-rc issue.

It is strange to watch how a bug in Debian causing KDM to fail to start at boot when an NVidia video card is used is handled. The problem seem to be that the nvidia X.org driver uses a long time to initialize, and this duration is longer than kdm is configured to wait.

I came across two bugs related to this issue, #583312 initially filed against initscripts and passed on to nvidia-glx when it became obvious that the nvidia drivers were involved, and #524751 initially filed against kdm and passed on to src:nvidia-graphics-drivers for unknown reasons.

To me, it seem that no-one is interested in actually solving the problem nvidia video card owners experience and make sure the Debian distribution work out of the box for these users. The nvidia driver maintainers expect kdm to be set up to wait longer, while kdm expect the nvidia driver maintainers to fix the driver to start faster, and while they wait for each other I guess the users end up switching to a distribution that work for them. I have no idea what the solution is, but I am pretty sure that waiting for each other is not it.

I wonder why we end up handling bugs this way.

When using sitesummary at a site to track machines, it is possible to get a list of the machine types in use thanks to the DMI information extracted from each machine. The script to do so is included in the sitesummary package, and here is example output from the Skolelinux build servers:

maintainer:~# /usr/lib/sitesummary/hardware-model-summary
  vendor                    count
  Dell Computer Corporation     1
    PowerEdge 1750              1
  IBM                           1
    eserver xSeries 345 -[8670M1X]-     1
  Intel                         2
  [no-dmi-info]                 3
maintainer:~#

The quality of the report depend on the quality of the DMI tables provided in each machine. Here there are Intel machines without model information listed with Intel as vendor and mo model, and virtual Xen machines listed as [no-dmi-info]. One can add -l as a command line option to list the individual machines.

A larger list is available from the the city of Narvik, which uses Skolelinux on all their shools and also provide the basic sitesummary report publicly. In their report there are ~1400 machines. I know they use both Ubuntu and Skolelinux on their machines, and as sitesummary is available in both distributions, it is trivial to get all of them to report to the same central collector.

Via the blog of Rob Weir I came across the very interesting essay named The Art of Standards Wars (PDF 25 pages). I recommend it for everyone following the standards wars of today.

If Debian is to migrate to upstart on Linux, I expect some init.d scripts to migrate (some of) their operations to upstart job while keeping the init.d for hurd and kfreebsd. The packages with such needs will need a way to get their init.d scripts to behave differently when used with sysvinit and with upstart. Because of this, I had a look at the environment variables set when a init.d script is running under upstart, and when it is not.

With upstart, I notice these environment variables are set when a script is started from rcS.d/ (ignoring some irrelevant ones like COLUMNS):

DEFAULT_RUNLEVEL=2
previous=N
PREVLEVEL=
RUNLEVEL=
runlevel=S
UPSTART_EVENTS=startup
UPSTART_INSTANCE=
UPSTART_JOB=rc-sysinit

With sysvinit, these environment variables are set for the same script.

INIT_VERSION=sysvinit-2.88
previous=N
PREVLEVEL=N
RUNLEVEL=S
runlevel=S

The RUNLEVEL and PREVLEVEL environment variables passed on from sysvinit are not set by upstart. Not sure if it is intentional or not to not be compatible with sysvinit in this regard.

For scripts needing to behave differently when upstart is used, looking for the UPSTART_JOB environment variable seem to be a good choice.

The last few days I have done some upgrade testing in Debian, to see if the upgrade from Lenny to Squeeze will go smoothly. A few bugs have been discovered and reported in the process (#585410 in nagios3-cgi, #584879 already fixed in enscript and #584861 in kdebase-workspace-data), and to get a more regular testing going on, I am working on a script to automate the test.

The idea is to create a Lenny chroot and use tasksel to install a Gnome or KDE desktop installation inside the chroot before upgrading it. To ensure no services are started in the chroot, a policy-rc.d script is inserted. To make sure tasksel believe it is to install a desktop on a laptop, the tasksel tests are replaced in the chroot (only acceptable because this is a throw-away chroot).

A naive upgrade from Lenny to Squeeze using aptitude dist-upgrade currently always fail because udev refuses to upgrade with the kernel in Lenny, so to avoid that problem the file /etc/udev/kernel-upgrade is created. The bug report #566000 make me suspect this problem do not trigger in a chroot, but I touch the file anyway to make sure the upgrade go well. Testing on virtual and real hardware have failed me because of udev so far, and creating this file do the trick in such settings anyway. This is a known issue and the current udev behaviour is intended by the udev maintainer because he lack the resources to rewrite udev to keep working with old kernels or something like that. I really wish the udev upstream would keep udev backwards compatible, to avoid such upgrade problem, but given that they fail to do so, I guess documenting the way out of this mess is the best option we got for Debian Squeeze.

Anyway, back to the task at hand, testing upgrades. This test script, which I call upgrade-test for now, is doing the trick:

#!/bin/sh
set -ex

if [ "$1" ] ; then
    desktop=$1
else
    desktop=gnome
fi

from=lenny
to=squeeze

exec < /dev/null
unset LANG
mirror=http://ftp.skolelinux.org/debian
tmpdir=chroot-$from-upgrade-$to-$desktop
fuser -mv .
debootstrap $from $tmpdir $mirror
chroot $tmpdir aptitude update
cat > $tmpdir/usr/sbin/policy-rc.d <<EOF
#!/bin/sh
exit 101
EOF
chmod a+rx $tmpdir/usr/sbin/policy-rc.d
exit_cleanup() {
    umount $tmpdir/proc
}
mount -t proc proc $tmpdir/proc
# Make sure proc is unmounted also on failure
trap exit_cleanup EXIT INT

chroot $tmpdir aptitude -y install debconf-utils

# Make sure tasksel autoselection trigger.  It need the test scripts
# to return the correct answers.
echo tasksel tasksel/desktop multiselect $desktop | \
    chroot $tmpdir debconf-set-selections

# Include the desktop and laptop task
for test in desktop laptop ; do
    echo > $tmpdir/usr/lib/tasksel/tests/$test <<EOF
#!/bin/sh
exit 2
EOF
    chmod a+rx $tmpdir/usr/lib/tasksel/tests/$test
done

DEBIAN_FRONTEND=noninteractive
DEBIAN_PRIORITY=critical
export DEBIAN_FRONTEND DEBIAN_PRIORITY
chroot $tmpdir tasksel --new-install

echo deb $mirror $to main > $tmpdir/etc/apt/sources.list
chroot $tmpdir aptitude update
touch $tmpdir/etc/udev/kernel-upgrade
chroot $tmpdir aptitude -y dist-upgrade
fuser -mv

I suspect it would be useful to test upgrades with both apt-get and with aptitude, but I have not had time to look at how they behave differently so far. I hope to get a cron job running to do the test regularly and post the result on the web. The Gnome upgrade currently work, while the KDE upgrade fail because of the bug in kdebase-workspace-data

I am not quite sure what kind of extract from the huge upgrade logs (KDE 167 KiB, Gnome 516 KiB) it make sense to include in this blog post, so I will refrain from trying. I can report that for Gnome, aptitude report 760 packages upgraded, 448 newly installed, 129 to remove and 1 not upgraded and 1024MB need to be downloaded while for KDE the same numbers are 702 packages upgraded, 507 newly installed, 193 to remove and 0 not upgraded and 1117MB need to be downloaded

I am very happy to notice that the Gnome desktop + laptop upgrade is able to migrate to dependency based boot sequencing and parallel booting without a hitch. Was unsure if there were still bugs with packages failing to clean up their obsolete init.d script during upgrades, and no such problem seem to affect the Gnome desktop+laptop packages.

My testing of Debian upgrades from Lenny to Squeeze continues, and I've finally made the upgrade logs available from http://people.skolelinux.org/pere/debian-upgrade-testing/. I am now testing dist-upgrade of Gnome and KDE in a chroot using both apt and aptitude, and found their differences interesting. This time I will only focus on their removal plans.

After installing a Gnome desktop and the laptop task, apt-get wants to remove 72 packages when dist-upgrading from Lenny to Squeeze. The surprising part is that it want to remove xorg and all xserver-xorg-video* drivers. Clearly not a good choice, but I am not sure why. When asking aptitude to do the same, it want to remove 129 packages, but most of them are library packages I suspect are no longer needed. Both of them want to remove bluetooth packages, which I do not know. Perhaps these bluetooth packages are obsolete?

For KDE, apt-get want to remove 82 packages, among them kdebase which seem like a bad idea and xorg the same way as with Gnome. Asking aptitude for the same, it wants to remove 192 packages, none which are too surprising.

I guess the removal of xorg during upgrades should be investigated and avoided, and perhaps others as well. Here are the complete list of planned removals. The complete logs is available from the URL above. Note if you want to repeat these tests, that the upgrade test for kde+apt-get hung in the tasksel setup because of dpkg asking conffile questions. No idea why. I worked around it by using 'echo >> /proc/pidofdpkg/fd/0' to tell dpkg to continue.

apt-get gnome 72
bluez-gnome cupsddk-drivers deskbar-applet gnome gnome-desktop-environment gnome-network-admin gtkhtml3.14 iceweasel-gnome-support libavcodec51 libdatrie0 libgdl-1-0 libgnomekbd2 libgnomekbdui2 libmetacity0 libslab0 libxcb-xlib0 nautilus-cd-burner python-gnome2-desktop python-gnome2-extras serpentine swfdec-mozilla update-manager xorg xserver-xorg xserver-xorg-core xserver-xorg-input-all xserver-xorg-input-evdev xserver-xorg-input-kbd xserver-xorg-input-mouse xserver-xorg-input-synaptics xserver-xorg-input-wacom xserver-xorg-video-all xserver-xorg-video-apm xserver-xorg-video-ark xserver-xorg-video-ati xserver-xorg-video-chips xserver-xorg-video-cirrus xserver-xorg-video-cyrix xserver-xorg-video-dummy xserver-xorg-video-fbdev xserver-xorg-video-glint xserver-xorg-video-i128 xserver-xorg-video-i740 xserver-xorg-video-imstt xserver-xorg-video-intel xserver-xorg-video-mach64 xserver-xorg-video-mga xserver-xorg-video-neomagic xserver-xorg-video-nsc xserver-xorg-video-nv xserver-xorg-video-openchrome xserver-xorg-video-r128 xserver-xorg-video-radeon xserver-xorg-video-radeonhd xserver-xorg-video-rendition xserver-xorg-video-s3 xserver-xorg-video-s3virge xserver-xorg-video-savage xserver-xorg-video-siliconmotion xserver-xorg-video-sis xserver-xorg-video-sisusb xserver-xorg-video-tdfx xserver-xorg-video-tga xserver-xorg-video-trident xserver-xorg-video-tseng xserver-xorg-video-v4l xserver-xorg-video-vesa xserver-xorg-video-vga xserver-xorg-video-vmware xserver-xorg-video-voodoo xulrunner-1.9 xulrunner-1.9-gnome-support

aptitude gnome 129
bluez-gnome bluez-utils cpp-4.3 cupsddk-drivers dhcdbd djvulibre-desktop finger gnome-app-install gnome-mount gnome-network-admin gnome-spell gnome-vfs-obexftp gnome-volume-manager gstreamer0.10-gnomevfs gtkhtml3.14 libao2 libavahi-compat-libdnssd1 libavahi-core5 libavcodec51 libbluetooth2 libcamel1.2-11 libcdio7 libcucul0 libcupsys2 libcurl3 libdatrie0 libdirectfb-1.0-0 libdvdread3 libedataserver1.2-9 libeel2-2.20 libeel2-data libepc-1.0-1 libepc-ui-1.0-1 libfaad0 libgail-common libgd2-noxpm libgda3-3 libgda3-common libgdl-1-0 libgdl-1-common libggz2 libggzcore9 libggzmod4 libgksu1.2-0 libgksuui1.0-1 libgmyth0 libgnomecups1.0-1 libgnomekbd2 libgnomekbdui2 libgnomeprint2.2-0 libgnomeprint2.2-data libgnomeprintui2.2-0 libgnomeprintui2.2-common libgnomevfs2-bin libgpod3 libgraphviz4 libgtkhtml2-0 libgtksourceview-common libgtksourceview1.0-0 libgucharmap6 libhesiod0 libicu38 libiw29 libkpathsea4 libltdl3 libmagick++10 libmagick10 libmalaga7 libmetacity0 libmtp7 libmysqlclient15off libnautilus-burn4 libneon27 libnm-glib0 libnm-util0 libopal-2.2 libosp5 libparted1.8-10 libpoppler-glib3 libpoppler3 libpt-1.10.10 libpt-1.10.10-plugins-alsa libpt-1.10.10-plugins-v4l libraw1394-8 libsensors3 libslab0 libsmbios2 libsoup2.2-8 libssh2-1 libsuitesparse-3.1.0 libswfdec-0.6-90 libtalloc1 libtotem-plparser10 libtrackerclient0 libxalan2-java libxalan2-java-gcj libxcb-xlib0 libxerces2-java libxerces2-java-gcj libxklavier12 libxtrap6 libxxf86misc1 libzephyr3 mysql-common nautilus-cd-burner openoffice.org-writer2latex openssl-blacklist p7zip python-4suite-xml python-eggtrayicon python-gnome2-desktop python-gnome2-extras python-gtkhtml2 python-gtkmozembed python-numeric python-sexy serpentine svgalibg1 swfdec-gnome swfdec-mozilla totem-gstreamer update-manager wodim xserver-xorg-video-cyrix xserver-xorg-video-imstt xserver-xorg-video-nsc xserver-xorg-video-v4l xserver-xorg-video-vga zip

apt-get kde 82
cupsddk-drivers karm kaudiocreator kcoloredit kcontrol kde kde-core kdeaddons kdeartwork kdebase kdebase-bin kdebase-bin-kde3 kdebase-kio-plugins kdesktop kdeutils khelpcenter kicker kicker-applets knewsticker kolourpaint konq-plugins konqueror korn kpersonalizer kscreensaver ksplash libavcodec51 libdatrie0 libkiten1 libxcb-xlib0 quanta superkaramba texlive-base-bin xorg xserver-xorg xserver-xorg-core xserver-xorg-input-all xserver-xorg-input-evdev xserver-xorg-input-kbd xserver-xorg-input-mouse xserver-xorg-input-synaptics xserver-xorg-input-wacom xserver-xorg-video-all xserver-xorg-video-apm xserver-xorg-video-ark xserver-xorg-video-ati xserver-xorg-video-chips xserver-xorg-video-cirrus xserver-xorg-video-cyrix xserver-xorg-video-dummy xserver-xorg-video-fbdev xserver-xorg-video-glint xserver-xorg-video-i128 xserver-xorg-video-i740 xserver-xorg-video-imstt xserver-xorg-video-intel xserver-xorg-video-mach64 xserver-xorg-video-mga xserver-xorg-video-neomagic xserver-xorg-video-nsc xserver-xorg-video-nv xserver-xorg-video-openchrome xserver-xorg-video-r128 xserver-xorg-video-radeon xserver-xorg-video-radeonhd xserver-xorg-video-rendition xserver-xorg-video-s3 xserver-xorg-video-s3virge xserver-xorg-video-savage xserver-xorg-video-siliconmotion xserver-xorg-video-sis xserver-xorg-video-sisusb xserver-xorg-video-tdfx xserver-xorg-video-tga xserver-xorg-video-trident xserver-xorg-video-tseng xserver-xorg-video-v4l xserver-xorg-video-vesa xserver-xorg-video-vga xserver-xorg-video-vmware xserver-xorg-video-voodoo xulrunner-1.9

aptitude kde 192
bluez-utils cpp-4.3 cupsddk-drivers cvs dcoprss dhcdbd djvulibre-desktop dosfstools eyesapplet fifteenapplet finger gettext ghostscript-x imlib-base imlib11 indi kandy karm kasteroids kaudiocreator kbackgammon kbstate kcoloredit kcontrol kcron kdat kdeadmin-kfile-plugins kdeartwork-misc kdeartwork-theme-window kdebase-bin-kde3 kdebase-kio-plugins kdeedu-data kdegraphics-kfile-plugins kdelirc kdemultimedia-kappfinder-data kdemultimedia-kfile-plugins kdenetwork-kfile-plugins kdepim-kfile-plugins kdepim-kio-plugins kdeprint kdesktop kdessh kdict kdnssd kdvi kedit keduca kenolaba kfax kfaxview kfouleggs kghostview khelpcenter khexedit kiconedit kitchensync klatin klickety kmailcvt kmenuedit kmid kmilo kmoon kmrml kodo kolourpaint kooka korn kpager kpdf kpercentage kpf kpilot kpoker kpovmodeler krec kregexpeditor ksayit ksim ksirc ksirtet ksmiletris ksmserver ksnake ksokoban ksplash ksvg ksysv ktip ktnef kuickshow kverbos kview kviewshell kvoctrain kwifimanager kwin kwin4 kworldclock kxsldbg libakode2 libao2 libarts1-akode libarts1-audiofile libarts1-mpeglib libarts1-xine libavahi-compat-libdnssd1 libavahi-core5 libavc1394-0 libavcodec51 libbluetooth2 libboost-python1.34.1 libcucul0 libcurl3 libcvsservice0 libdatrie0 libdirectfb-1.0-0 libdjvulibre21 libdvdread3 libfaad0 libfreebob0 libgail-common libgd2-noxpm libgraphviz4 libgsmme1c2a libgtkhtml2-0 libicu38 libiec61883-0 libindex0 libiw29 libk3b3 libkcal2b libkcddb1 libkdeedu3 libkdepim1a libkgantt0 libkiten1 libkleopatra1 libkmime2 libkpathsea4 libkpimexchange1 libkpimidentities1 libkscan1 libksieve0 libktnef1 liblockdev1 libltdl3 libmagick10 libmimelib1c2a libmozjs1d libmpcdec3 libneon27 libnm-util0 libopensync0 libpisock9 libpoppler-glib3 libpoppler-qt2 libpoppler3 libraw1394-8 libsmbios2 libssh2-1 libsuitesparse-3.1.0 libtalloc1 libtiff-tools libxalan2-java libxalan2-java-gcj libxcb-xlib0 libxerces2-java libxerces2-java-gcj libxtrap6 mpeglib networkstatus openoffice.org-writer2latex pmount poster psutils quanta quanta-data superkaramba svgalibg1 tex-common texlive-base texlive-base-bin texlive-common texlive-doc-base texlive-fonts-recommended xserver-xorg-video-cyrix xserver-xorg-video-imstt xserver-xorg-video-nsc xserver-xorg-video-v4l xserver-xorg-video-vga xulrunner-1.9

For those of us caring about document exchange and interoperability, OfficeShots is a great service. It is to ODF documents what BrowserShots is for web pages.

A while back, I was contacted by Knut Yrvin at the part of Nokia that used to be Trolltech, who wanted to help the OfficeShots project and wondered if the University of Oslo where I work would be interested in supporting the project. I helped him to navigate his request to the right people at work, and his request was answered with a spot in the machine room with power and network connected, and Knut arranged funding for a machine to fill the spot. The machine is administrated by the OfficeShots people, so I do not have daily contact with its progress, and thus from time to time check back to see how the project is doing.

Today I had a look, and was happy to see that the Dell box in our machine room now is the host for several virtual machines running as OfficeShots factories, and the project is able to render ODF documents in 17 different document processing implementation on Linux and Windows. This is great.

A few times I have had the need to simulate the way tasksel installs packages during the normal debian-installer run. Until now, I have ended up letting tasksel do the work, with the annoying problem of not getting any feedback at all when something fails (like a conffile question from dpkg or a download that fails), using code like this:

export DEBIAN_FRONTEND=noninteractive
tasksel --new-install

This would invoke tasksel, let its automatic task selection pick the tasks to install, and continue to install the requested tasks without any output what so ever. Recently I revisited this problem while working on the automatic package upgrade testing, because tasksel would some times hang without any useful feedback, and I want to see what is going on when it happen. Then it occured to me, I can parse the output from tasksel when asked to run in test mode, and use that aptitude command line printed by tasksel then to simulate the tasksel run. I ended up using code like this:

export DEBIAN_FRONTEND=noninteractive
cmd="$(in_target tasksel -t --new-install | sed 's/debconf-apt-progress -- //')"
$cmd

The content of $cmd is typically something like "aptitude -q --without-recommends -o APT::Install-Recommends=no -y install ~t^desktop$ ~t^gnome-desktop$ ~t^laptop$ ~pstandard ~prequired ~pimportant", which will install the gnome desktop task, the laptop task and all packages with priority standard , required and important, just like tasksel would have done it during installation.

A better approach is probably to extend tasksel to be able to install packages without using debconf-apt-progress, for use cases like this.

A while back, I complained about the fact that it is not possible with the provided schemas for storing DNS and DHCP information in LDAP to combine the two sets of information into one LDAP object representing a computer.

In the mean time, I discovered that a simple fix would be to make the dhcpHost object class auxiliary, to allow it to be combined with the dNSDomain object class, and thus forming one object for one computer when storing both DHCP and DNS information in LDAP.

If I understand this correctly, it is not safe to do this change without also changing the assigned number for the object class, and I do not know enough about LDAP schema design to do that properly for Debian Edu.

Anyway, for future reference, this is how I believe we could change the DHCP schema to solve at least part of the problem with the LDAP schemas available today from IETF.

--- dhcp.schema    (revision 65192)
+++ dhcp.schema    (working copy)
@@ -376,7 +376,7 @@
 objectclass ( 2.16.840.1.113719.1.203.6.6
        NAME 'dhcpHost'
        DESC 'This represents information about a particular client'
-       SUP top
+       SUP top AUXILIARY
        MUST cn
        MAY  (dhcpLeaseDN $ dhcpHWAddress $ dhcpOptionsDN $ dhcpStatements $ dhcpComments $ dhcpOption)
        X-NDS_CONTAINMENT ('dhcpService' 'dhcpSubnet' 'dhcpGroup') )

I very much welcome clues on how to do this properly for Debian Edu/Squeeze. We provide the DHCP schema in our debian-edu-config package, and should thus be free to rewrite it as we see fit.

If you want to help out with implementing this for Debian Edu, please contact us on debian-edu@lists.debian.org.

The last few days I have been looking into the status of the LDAP directory in Debian Edu, and in the process I started to miss a GUI tool to browse the LDAP tree. The only one I was able to find in Debian/Squeeze and Lenny is LUMA, which has proved to be a great tool to get a overview of the current LDAP directory populated by default in Skolelinux. Thanks to it, I have been able to find empty and obsolete subtrees, misplaced objects and duplicate objects. It will be installed by default in Debian/Squeeze. If you are working with LDAP, give it a go. :)

I did notice one problem with it I have not had time to report to the BTS yet. There is no .desktop file in the package, so the tool do not show up in the Gnome and KDE menus, but only deep down in in the Debian submenu in KDE. I hope that can be fixed before Squeeze is released.

I have not yet been able to get it to modify the tree yet. I would like to move objects and remove subtrees directly in the GUI, but have not found a way to do that with LUMA yet. So in the mean time, I use ldapvi for that.

If you have tips on other GUI tools for LDAP that might be useful in Debian Edu, please contact us on debian-edu@lists.debian.org.

Update 2010-06-29: Ross Reedstrom tipped us about the gq package as a useful GUI alternative. It seem like a good tool, but is unmaintained in Debian and got a RC bug keeping it out of Squeeze. Unless that changes, it will not be an option for Debian Edu based on Squeeze.

For a laptop, centralized user directories and password checking is a bit troubling. Laptops are typically used also when not connected to the network, and it is vital for a user to be able to log in or unlock the screen saver also when a central server is unavailable. This is possible by caching passwords and directory information (user and group attributes) locally, and the packages to do so are available in Debian. Here follow two recipes to set this up in Debian/Squeeze. It is also possible to set up in Debian/Lenny, but require more manual setup there because pam-auth-update is missing in Lenny.

LDAP/Kerberos + nscd + libpam-ccreds + libpam-mklocaluser/pam_mkhomedir

This is the traditional method with a twist. The password caching is provided by libpam-ccreds (version 10-4 or later is needed on Squeeze), and the directory caching is done by nscd. The directory lookup and password checking is done using LDAP. If one want to use Kerberos for password checking the libpam-ldapd package can be replaced with libpam-krb5 or libpam-heimdal. If one is happy having a local home directory with the path listed in LDAP, one can use the pam_mkhomedir module from pam-modules to make this happen instead of using libpam-mklocaluser. A setup for pam-auth-update to enable pam_mkhomedir will have to be written until a fix for bug #568577 is in the archive. Because I believe it is a bad idea to have local home directories using misleading paths like /site/server/partition/, I prefer to create a local user with the home directory in /home/. This is done using the libpam-mklocaluser package.

These packages need to be installed and configured

libnss-ldapd libpam-ldapd nscd libpam-ccreds libpam-mklocaluser

The ldapd packages will ask for LDAP connection information, and one have to fill in the values that fits ones own site. Make sure the PAM part uses encrypted connections, to make sure the password is not sent in clear text to the LDAP server. I've been unable to get TLS certificate checking for a self signed certificate working, which make LDAP authentication unsafe for Debian Edu (nslcd is not checking if it is talking to the correct LDAP server), and very much welcome feedback on how to get this working.

Because nscd do not have a default configuration fit for offline caching until bug #485282 is fixed, this configuration should be used instead of the one currently in /etc/nscd.conf. The changes are in the fields reload-count and positive-time-to-live, and is based on the instructions I found in the LDAP for Mobile Laptops instructions by Flyn Computing.

	debug-level		0
	reload-count		unlimited
	paranoia		no

	enable-cache		passwd		yes
	positive-time-to-live	passwd		2592000
	negative-time-to-live	passwd		20
	suggested-size		passwd		211
	check-files		passwd		yes
	persistent		passwd		yes
	shared			passwd		yes
	max-db-size		passwd		33554432
	auto-propagate		passwd		yes

	enable-cache		group		yes
	positive-time-to-live	group		2592000
	negative-time-to-live	group		20
	suggested-size		group		211
	check-files		group		yes
	persistent		group		yes
	shared			group		yes
	max-db-size		group		33554432
	auto-propagate		group		yes

	enable-cache		hosts		no
	positive-time-to-live	hosts		2592000
	negative-time-to-live	hosts		20
	suggested-size		hosts		211
	check-files		hosts		yes
	persistent		hosts		yes
	shared			hosts		yes
	max-db-size		hosts		33554432

	enable-cache		services	yes
	positive-time-to-live	services	2592000
	negative-time-to-live	services	20
	suggested-size		services	211
	check-files		services	yes
	persistent		services	yes
	shared			services	yes
	max-db-size		services	33554432

While we wait for a mechanism to update /etc/nsswitch.conf automatically like the one provided in bug #496915, the file content need to be manually replaced to ensure LDAP is used as the directory service on the machine. /etc/nsswitch.conf should normally look like this:

passwd:         files ldap
group:          files ldap
shadow:         files ldap
hosts:          files mdns4_minimal [NOTFOUND=return] dns mdns4
networks:       files
protocols:      files
services:       files
ethers:         files
rpc:            files
netgroup:       files ldap

The important parts are that ldap is listed last for passwd, group, shadow and netgroup.

With these changes in place, any user in LDAP will be able to log in locally on the machine using for example kdm, get a local home directory created and have the password as well as user and group attributes cached.

LDAP/Kerberos + nss-updatedb + libpam-ccreds + libpam-mklocaluser/pam_mkhomedir

Because nscd have had its share of problems, and seem to have problems doing proper caching, I've seen suggestions and recipes to use nss-updatedb to copy parts of the LDAP database locally when the LDAP database is available. I have not tested such setup, because I discovered sssd.

LDAP/Kerberos + sssd + libpam-mklocaluser

A more flexible and robust setup than the nscd combination mentioned earlier that has shown up recently, is the sssd package from Redhat. It is part of the FreeIPA project to provide a Active Directory like directory service for Linux machines. The sssd system combines the caching of passwords and user information into one package, and remove the need for nscd and libpam-ccreds. It support LDAP and Kerberos, but not NIS. Version 1.2 do not support netgroups, but it is said that it will support this in version 1.5 expected to show up later in 2010. Because the sssd package was missing in Debian, I ended up co-maintaining it with Werner, and version 1.2 is now in testing.

These packages need to be installed and configured to get the roaming setup I want

libpam-sss libnss-sss libpam-mklocaluser

The complete setup of sssd is done by editing/creating /etc/sssd/sssd.conf.

[sssd]
config_file_version = 2
reconnection_retries = 3
sbus_timeout = 30
services = nss, pam
domains = INTERN

[nss]
filter_groups = root
filter_users = root
reconnection_retries = 3

[pam]
reconnection_retries = 3

[domain/INTERN]
enumerate = false
cache_credentials = true

id_provider = ldap
auth_provider = ldap
chpass_provider = ldap

ldap_uri = ldap://ldap
ldap_search_base = dc=skole,dc=skolelinux,dc=no
ldap_tls_reqcert = never
ldap_tls_cacert = /etc/ssl/certs/ca-certificates.crt

I got the same problem here with certificate checking. Had to set "ldap_tls_reqcert = never" to get it working.

With the libnss-sss package in testing at the moment, the nsswitch.conf file is update automatically, so there is no need to modify it manually.

If you want to help out with implementing this for Debian Edu, please contact us on debian-edu@lists.debian.org.

Here is a short update on my my Debian Lenny->Squeeze upgrade testing. Here is a summary of the difference for Gnome when it is upgraded by apt-get and aptitude. I'm not reporting the status for KDE, because the upgrade crashes when aptitude try because of missing conflicts (#584861 and #585716).

At the end of the upgrade test script, dpkg -l is executed to get a complete list of the installed packages. Based on this I see these differences when I did a test run today. As usual, I do not really know what the correct set of packages would be, but thought it best to publish the difference.

Installed using apt-get, missing with aptitude

at-spi cpp-4.3 finger gnome-spell gstreamer0.10-gnomevfs libatspi1.0-0 libcupsys2 libeel2-data libgail-common libgdl-1-common libgnomeprint2.2-data libgnomeprintui2.2-common libgnomevfs2-bin libgtksourceview-common libpt-1.10.10-plugins-alsa libpt-1.10.10-plugins-v4l libservlet2.4-java libxalan2-java libxerces2-java openoffice.org-writer2latex openssl-blacklist p7zip python-4suite-xml python-eggtrayicon python-gtkhtml2 python-gtkmozembed svgalibg1 xserver-xephyr zip

Installed using apt-get, removed with aptitude

bluez-utils dhcdbd djvulibre-desktop epiphany-gecko gnome-app-install gnome-mount gnome-vfs-obexftp gnome-volume-manager libao2 libavahi-compat-libdnssd1 libavahi-core5 libbind9-50 libbluetooth2 libcamel1.2-11 libcdio7 libcucul0 libcurl3 libdirectfb-1.0-0 libdvdread3 libedata-cal1.2-6 libedataserver1.2-9 libeel2-2.20 libepc-1.0-1 libepc-ui-1.0-1 libexchange-storage1.2-3 libfaad0 libgd2-noxpm libgda3-3 libgda3-common libggz2 libggzcore9 libggzmod4 libgksu1.2-0 libgksuui1.0-1 libgmyth0 libgnome-desktop-2 libgnome-pilot2 libgnomecups1.0-1 libgnomeprint2.2-0 libgnomeprintui2.2-0 libgpod3 libgraphviz4 libgtkhtml2-0 libgtksourceview1.0-0 libgucharmap6 libhesiod0 libicu38 libisccc50 libisccfg50 libiw29 libkpathsea4 libltdl3 liblwres50 libmagick++10 libmagick10 libmalaga7 libmtp7 libmysqlclient15off libnautilus-burn4 libneon27 libnm-glib0 libnm-util0 libopal-2.2 libosp5 libparted1.8-10 libpisock9 libpisync1 libpoppler-glib3 libpoppler3 libpt-1.10.10 libraw1394-8 libsensors3 libsmbios2 libsoup2.2-8 libssh2-1 libsuitesparse-3.1.0 libswfdec-0.6-90 libtalloc1 libtotem-plparser10 libtrackerclient0 libvoikko1 libxalan2-java-gcj libxerces2-java-gcj libxklavier12 libxtrap6 libxxf86misc1 libzephyr3 mysql-common swfdec-gnome totem-gstreamer wodim

Installed using aptitude, missing with apt-get

gnome gnome-desktop-environment hamster-applet python-gnomeapplet python-gnomekeyring python-wnck rhythmbox-plugins xorg xserver-xorg-input-all xserver-xorg-input-evdev xserver-xorg-input-kbd xserver-xorg-input-mouse xserver-xorg-input-synaptics xserver-xorg-video-all xserver-xorg-video-apm xserver-xorg-video-ark xserver-xorg-video-ati xserver-xorg-video-chips xserver-xorg-video-cirrus xserver-xorg-video-dummy xserver-xorg-video-fbdev xserver-xorg-video-glint xserver-xorg-video-i128 xserver-xorg-video-i740 xserver-xorg-video-mach64 xserver-xorg-video-mga xserver-xorg-video-neomagic xserver-xorg-video-nouveau xserver-xorg-video-nv xserver-xorg-video-r128 xserver-xorg-video-radeon xserver-xorg-video-radeonhd xserver-xorg-video-rendition xserver-xorg-video-s3 xserver-xorg-video-s3virge xserver-xorg-video-savage xserver-xorg-video-siliconmotion xserver-xorg-video-sis xserver-xorg-video-sisusb xserver-xorg-video-tdfx xserver-xorg-video-tga xserver-xorg-video-trident xserver-xorg-video-tseng xserver-xorg-video-vesa xserver-xorg-video-vmware xserver-xorg-video-voodoo

Installed using aptitude, removed with apt-get

deskbar-applet xserver-xorg xserver-xorg-core xserver-xorg-input-wacom xserver-xorg-video-intel xserver-xorg-video-openchrome

I was told on IRC that the xorg-xserver package was changed in git today to try to get apt-get to not remove xorg completely. No idea when it hits Squeeze, but when it does I hope it will reduce the difference somewhat.

Since my last post about available LDAP tools in Debian, I was told about a LDAP GUI that is even better than luma. The java application jXplorer is claimed to be capable of moving LDAP objects and subtrees using drag-and-drop, and can authenticate using Kerberos. I have only tested the Kerberos authentication, but do not have a LDAP setup allowing me to rewrite LDAP with my test user yet. It is available in Debian testing and unstable at the moment. The only problem I have with it is how it handle errors. If something go wrong, its non-intuitive behaviour require me to go through some query work list and remove the failing query. Nothing big, but very annoying.

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 ( 1.1.2.2 NAME 'ltspClientAux'
#     SUP top
#     AUXILIARY
#     MAY ( ltspConfigServer $ ltsConfigSound $ ... )

LDAPSERVER=$(debian-edu-ldapserver)
if [ "$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"
	done
    done
fi

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 debian-edu@lists.debian.org.

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 redhat.com.

For a while now, I have wanted to find a way to change the DNS and DHCP services in Debian Edu to use the same LDAP objects for a given computer, to avoid the possibility of having a inconsistent state for a computer in LDAP (as in DHCP but no DNS entry or the other way around) and make it easier to add computers to LDAP.

I've looked at how powerdns and dhcpd is using LDAP, and using this information finally found a solution that seem to work.

The old setup required three LDAP objects for a given computer. One forward DNS entry, one reverse DNS entry and one DHCP entry. If we switch powerdns to use its strict LDAP method (ldap-method=strict in pdns-debian-edu.conf), the forward and reverse DNS entries are merged into one while making it impossible to transfer the reverse map to a slave DNS server.

If we also replace the object class used to get the DNS related attributes to one allowing these attributes to be combined with the dhcphost object class, we can merge the DNS and DHCP entries into one. I've written such object class in the dnsdomainaux.schema file (need proper OIDs, but that is a minor issue), and tested the setup. It seem to work.

With this test setup in place, we can get away with one LDAP object for both DNS and DHCP, and even the LTSP configuration I suggested in an earlier email. The combined LDAP object will look something like this:

  dn: cn=hostname,cn=group1,cn=THINCLIENTS,cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
  cn: hostname
  objectClass: dhcphost
  objectclass: domainrelatedobject
  objectclass: dnsdomainaux
  associateddomain: hostname.intern
  arecord: 10.11.12.13
  dhcphwaddress: ethernet 00:00:00:00:00:00
  dhcpstatements: fixed-address hostname
  ldapconfigsound: Y

The DNS server uses the associateddomain and arecord entries, while the DHCP server uses the dhcphwaddress and dhcpstatements entries before asking DNS to resolve the fixed-adddress. LTSP will use dhcphwaddress or associateddomain and the ldapconfig* attributes.

I am not yet sure if I can get the DHCP server to look for its dhcphost in a different location, to allow us to put the objects outside the "DHCP Config" subtree, but hope to figure out a way to do that. If I can't figure out a way to do that, we can still get rid of the hosts subtree and move all its content into the DHCP Config tree (which probably should be renamed to be more related to the new content. I suspect cn=dnsdhcp,ou=services or something like that might be a good place to put it.

If you want to help out with implementing this for Debian Edu, please contact us on debian-edu@lists.debian.org.

This is a followup on my previous work on merging all the computer related LDAP objects in Debian Edu.

As a step to try to see if it possible to merge the DNS and DHCP LDAP objects, I have had a look at how the packages pdns-backend-ldap and dhcp3-server-ldap in Debian use the LDAP server. The two implementations are quite different in how they use LDAP.

To get this information, I started slapd with debugging enabled and dumped the debug output to a file to get the LDAP searches performed on a Debian Edu main-server. Here is a summary.

powerdns

Clues on how to set up PowerDNS to use a LDAP backend is available on the web.

PowerDNS have two modes of operation using LDAP as its backend. One "strict" mode where the forward and reverse DNS lookups are done using the same LDAP objects, and a "tree" mode where the forward and reverse entries are in two different subtrees in LDAP with a structure based on the DNS names, as in tjener.intern and 2.2.0.10.in-addr.arpa.

In tree mode, the server is set up to use a LDAP subtree as its base, and uses a "base" scoped search for the DNS name by adding "dc=tjener,dc=intern," to the base with a filter for "(associateddomain=tjener.intern)" for the forward entry and "dc=2,dc=2,dc=0,dc=10,dc=in-addr,dc=arpa," with a filter for "(associateddomain=2.2.0.10.in-addr.arpa)" for the reverse entry. For forward entries, it is looking for attributes named dnsttl, arecord, nsrecord, cnamerecord, soarecord, ptrrecord, hinforecord, mxrecord, txtrecord, rprecord, afsdbrecord, keyrecord, aaaarecord, locrecord, srvrecord, naptrrecord, kxrecord, certrecord, dsrecord, sshfprecord, ipseckeyrecord, rrsigrecord, nsecrecord, dnskeyrecord, dhcidrecord, spfrecord and modifytimestamp. For reverse entries it is looking for the attributes dnsttl, arecord, nsrecord, cnamerecord, soarecord, ptrrecord, hinforecord, mxrecord, txtrecord, rprecord, aaaarecord, locrecord, srvrecord, naptrrecord and modifytimestamp. The equivalent ldapsearch commands could look like this:

ldapsearch -h ldap \
  -b dc=tjener,dc=intern,ou=hosts,dc=skole,dc=skolelinux,dc=no \
  -s base -x '(associateddomain=tjener.intern)' dNSTTL aRecord nSRecord \
  cNAMERecord sOARecord pTRRecord hInfoRecord mXRecord tXTRecord \
  rPRecord aFSDBRecord KeyRecord aAAARecord lOCRecord sRVRecord \
  nAPTRRecord kXRecord certRecord dSRecord sSHFPRecord iPSecKeyRecord \
  rRSIGRecord nSECRecord dNSKeyRecord dHCIDRecord sPFRecord modifyTimestamp

ldapsearch -h ldap \
  -b dc=2,dc=2,dc=0,dc=10,dc=in-addr,dc=arpa,ou=hosts,dc=skole,dc=skolelinux,dc=no \
  -s base -x '(associateddomain=2.2.0.10.in-addr.arpa)'
  dnsttl, arecord, nsrecord, cnamerecord soarecord ptrrecord \
  hinforecord mxrecord txtrecord rprecord aaaarecord locrecord \
  srvrecord naptrrecord modifytimestamp

In Debian Edu/Lenny, the PowerDNS tree mode is used with ou=hosts,dc=skole,dc=skolelinux,dc=no as the base, and these are two example LDAP objects used there. In addition to these objects, the parent objects all th way up to ou=hosts,dc=skole,dc=skolelinux,dc=no also exist.

dn: dc=tjener,dc=intern,ou=hosts,dc=skole,dc=skolelinux,dc=no
objectclass: top
objectclass: dnsdomain
objectclass: domainrelatedobject
dc: tjener
arecord: 10.0.2.2
associateddomain: tjener.intern

dn: dc=2,dc=2,dc=0,dc=10,dc=in-addr,dc=arpa,ou=hosts,dc=skole,dc=skolelinux,dc=no
objectclass: top
objectclass: dnsdomain2
objectclass: domainrelatedobject
dc: 2
ptrrecord: tjener.intern
associateddomain: 2.2.0.10.in-addr.arpa

In strict mode, the server behaves differently. When looking for forward DNS entries, it is doing a "subtree" scoped search with the same base as in the tree mode for a object with filter "(associateddomain=tjener.intern)" and requests the attributes dnsttl, arecord, nsrecord, cnamerecord, soarecord, ptrrecord, hinforecord, mxrecord, txtrecord, rprecord, aaaarecord, locrecord, srvrecord, naptrrecord and modifytimestamp. For reverse entires it also do a subtree scoped search but this time the filter is "(arecord=10.0.2.2)" and the requested attributes are associateddomain, dnsttl and modifytimestamp. In short, in strict mode the objects with ptrrecord go away, and the arecord attribute in the forward object is used instead.

The forward and reverse searches can be simulated using ldapsearch like this:

ldapsearch -h ldap -b ou=hosts,dc=skole,dc=skolelinux,dc=no -s sub -x \
  '(associateddomain=tjener.intern)' dNSTTL aRecord nSRecord \
  cNAMERecord sOARecord pTRRecord hInfoRecord mXRecord tXTRecord \
  rPRecord aFSDBRecord KeyRecord aAAARecord lOCRecord sRVRecord \
  nAPTRRecord kXRecord certRecord dSRecord sSHFPRecord iPSecKeyRecord \
  rRSIGRecord nSECRecord dNSKeyRecord dHCIDRecord sPFRecord modifyTimestamp

ldapsearch -h ldap -b ou=hosts,dc=skole,dc=skolelinux,dc=no -s sub -x \
  '(arecord=10.0.2.2)' associateddomain dnsttl modifytimestamp

In addition to the forward and reverse searches , there is also a search for SOA records, which behave similar to the forward and reverse lookups.

A thing to note with the PowerDNS behaviour is that it do not specify any objectclass names, and instead look for the attributes it need to generate a DNS reply. This make it able to work with any objectclass that provide the needed attributes.

The attributes are normally provided in the cosine (RFC 1274) and dnsdomain2 schemas. The latter is used for reverse entries like ptrrecord and recent DNS additions like aaaarecord and srvrecord.

In Debian Edu, we have created DNS objects using the object classes dcobject (for dc), dnsdomain or dnsdomain2 (structural, for the DNS attributes) and domainrelatedobject (for associatedDomain). The use of structural object classes make it impossible to combine these classes with the object classes used by DHCP.

There are other schemas that could be used too, for example the dnszone structural object class used by Gosa and bind-sdb for the DNS attributes combined with the domainrelatedobject object class, but in this case some unused attributes would have to be included as well (zonename and relativedomainname).

My proposal for Debian Edu would be to switch PowerDNS to strict mode and not use any of the existing objectclasses (dnsdomain, dnsdomain2 and dnszone) when one want to combine the DNS information with DHCP information, and instead create a auxiliary object class defined something like this (using the attributes defined for dnsdomain and dnsdomain2 or dnszone):

objectclass ( some-oid NAME 'dnsDomainAux'
    SUP top
    AUXILIARY
    MAY ( ARecord $ MDRecord $ MXRecord $ NSRecord $ SOARecord $ CNAMERecord $
          DNSTTL $ DNSClass $ PTRRecord $ HINFORecord $ MINFORecord $
          TXTRecord $ SIGRecord $ KEYRecord $ AAAARecord $ LOCRecord $
          NXTRecord $ SRVRecord $ NAPTRRecord $ KXRecord $ CERTRecord $
          A6Record $ DNAMERecord
    ))

This will allow any object to become a DNS entry when combined with the domainrelatedobject object class, and allow any entity to include all the attributes PowerDNS wants. I've sent an email to the PowerDNS developers asking for their view on this schema and if they are interested in providing such schema with PowerDNS, and I hope my message will be accepted into their mailing list soon.

ISC dhcp

The DHCP server searches for specific objectclass and requests all the object attributes, and then uses the attributes it want. This make it harder to figure out exactly what attributes are used, but thanks to the working example in Debian Edu I can at least get an idea what is needed without having to read the source code.

In the DHCP server configuration, the LDAP base to use and the search filter to use to locate the correct dhcpServer entity is stored. These are the relevant entries from /etc/dhcp3/dhcpd.conf:

ldap-base-dn "dc=skole,dc=skolelinux,dc=no";
ldap-dhcp-server-cn "dhcp";

The DHCP server uses this information to nest all the DHCP configuration it need. The cn "dhcp" is located using the given LDAP base and the filter "(&(objectClass=dhcpServer)(cn=dhcp))". The search result is this entry:

dn: cn=dhcp,dc=skole,dc=skolelinux,dc=no
cn: dhcp
objectClass: top
objectClass: dhcpServer
dhcpServiceDN: cn=DHCP Config,dc=skole,dc=skolelinux,dc=no

The content of the dhcpServiceDN attribute is next used to locate the subtree with DHCP configuration. The DHCP configuration subtree base is located using a base scope search with base "cn=DHCP Config,dc=skole,dc=skolelinux,dc=no" and filter "(&(objectClass=dhcpService)(|(dhcpPrimaryDN=cn=dhcp,dc=skole,dc=skolelinux,dc=no)(dhcpSecondaryDN=cn=dhcp,dc=skole,dc=skolelinux,dc=no)))". The search result is this entry:

dn: cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
cn: DHCP Config
objectClass: top
objectClass: dhcpService
objectClass: dhcpOptions
dhcpPrimaryDN: cn=dhcp, dc=skole,dc=skolelinux,dc=no
dhcpStatements: ddns-update-style none
dhcpStatements: authoritative
dhcpOption: smtp-server code 69 = array of ip-address
dhcpOption: www-server code 72 = array of ip-address
dhcpOption: wpad-url code 252 = text

Next, the entire subtree is processed, one level at the time. When all the DHCP configuration is loaded, it is ready to receive requests. The subtree in Debian Edu contain objects with object classes top/dhcpService/dhcpOptions, top/dhcpSharedNetwork/dhcpOptions, top/dhcpSubnet, top/dhcpGroup and top/dhcpHost. These provide options and information about netmasks, dynamic range etc. Leaving out the details here because it is not relevant for the focus of my investigation, which is to see if it is possible to merge dns and dhcp related computer objects.

When a DHCP request come in, LDAP is searched for the MAC address of the client (00:00:00:00:00:00 in this example), using a subtree scoped search with "cn=DHCP Config,dc=skole,dc=skolelinux,dc=no" as the base and "(&(objectClass=dhcpHost)(dhcpHWAddress=ethernet 00:00:00:00:00:00))" as the filter. This is what a host object look like:

dn: cn=hostname,cn=group1,cn=THINCLIENTS,cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
cn: hostname
objectClass: top
objectClass: dhcpHost
dhcpHWAddress: ethernet 00:00:00:00:00:00
dhcpStatements: fixed-address hostname

There is less flexiblity in the way LDAP searches are done here. The object classes need to have fixed names, and the configuration need to be stored in a fairly specific LDAP structure. On the positive side, the invidiual dhcpHost entires can be anywhere without the DN pointed to by the dhcpServer entries. The latter should make it possible to group all host entries in a subtree next to the configuration entries, and this subtree can also be shared with the DNS server if the schema proposed above is combined with the dhcpHost structural object class.

Conclusion

The PowerDNS implementation seem to be very flexible when it come to which LDAP schemas to use. While its "tree" mode is rigid when it come to the the LDAP structure, the "strict" mode is very flexible, allowing DNS objects to be stored anywhere under the base cn specified in the configuration.

The DHCP implementation on the other hand is very inflexible, both regarding which LDAP schemas to use and which LDAP structure to use. I guess one could implement ones own schema, as long as the objectclasses and attributes have the names used, but this do not really help when the DHCP subtree need to have a fairly fixed structure.

Based on the observed behaviour, I suspect a LDAP structure like this might work for Debian Edu:

ou=services
  cn=machine-info (dhcpService) - dhcpServiceDN points here
    cn=dhcp (dhcpServer)
    cn=dhcp-internal (dhcpSharedNetwork/dhcpOptions)
      cn=10.0.2.0 (dhcpSubnet)
        cn=group1 (dhcpGroup/dhcpOptions)
    cn=dhcp-thinclients (dhcpSharedNetwork/dhcpOptions)
      cn=192.168.0.0 (dhcpSubnet)
        cn=group1 (dhcpGroup/dhcpOptions)
    ou=machines - PowerDNS base points here
      cn=hostname (dhcpHost/domainrelatedobject/dnsDomainAux)

This is not tested yet. If the DHCP server require the dhcpHost entries to be in the dhcpGroup subtrees, the entries can be stored there instead of a common machines subtree, and the PowerDNS base would have to be moved one level up to the machine-info subtree.

The combined object under the machines subtree would look something like this:

dn: dc=hostname,ou=machines,cn=machine-info,dc=skole,dc=skolelinux,dc=no
dc: hostname
objectClass: top
objectClass: dhcpHost
objectclass: domainrelatedobject
objectclass: dnsDomainAux
associateddomain: hostname.intern
arecord: 10.11.12.13
dhcpHWAddress: ethernet 00:00:00:00:00:00
dhcpStatements: fixed-address hostname.intern

One could even add the LTSP configuration associated with a given machine, as long as the required attributes are available in a auxiliary object class.

Thanks to todays opengeodata blog entry, I just discovered that the OpenStreetmap.org site have gotten support for calculating routes. The support is still experimental and only available from the development server, until more experience is gathered on the user interface and any scalability issues.

Earlier, the routing I knew about using the OpenStreetmap.org data was provided by Cloudmade, but having it on the main page is required to make everyone aware of the issue. I've had people reject Openstreetmap.org as a viable alternative for them because the front page lacked routing support, and I hope their needs will be catered for when routing show up on the www.openstreetmap.org front page.

The last few months me and the other Debian Edu developers have been working hard to get the Debian/Squeeze based version of Debian Edu/Skolelinux into shape. This future version will use Kerberos for authentication, and services are slowly migrated to single signon, getting rid of password questions one at the time.

It will also feature a roaming workstation profile with local home directory, for laptops that are only some times on the Skolelinux network, and for this profile a shortcut is created in Gnome and KDE to gain access to the users home directory on the file server. This shortcut uses SMB at the moment, and yesterday I had time to test if SMB mounting had started working in KDE after we added the cifs-utils package. I was pleasantly surprised how well it worked.

Thanks to the recent changes to our samba configuration to get it to use Kerberos for authentication, there were no question about user password when mounting the SMB volume. A simple click on the shortcut in the KDE menu, and a window with the home directory popped up. :)

One step closer to a single signon solution out of the box in Debian Edu. We already had PAM, LDAP, IMAP and SMTP in place, and now also Samba. Next step is Cups and hopefully also NFS.

We had planned a alpha0 release of Debian Edu for today, but thanks to the autobuilder administrators for some architectures being slow to sign packages, we are still missing the fixed LTSP package we need for the release. It was uploaded three days ago with urgency=high, and if it had entered testing yesterday we would have been able to test it in time for a alpha0 release today. As the binaries for ia64 and powerpc still not uploaded to the Debian archive, we need to delay the alpha release another day.

If you want to help out with implementing Kerberos for Debian Edu, please contact us on debian-edu@lists.debian.org.

I just posted this announcement culminating several months of work with the next Debian Edu release. Not nearly done, but one major step completed.

This is the first test release based on Squeeze. The focus of this release is to test the user application selection. To have a look, install the standalone profile and let the developers know if the set of installed packages i.e. applications should be modified. If some user application is missing, or if there are some applications that no longer make sense to be included in Debian Edu, please let us know. Also, if a useful application is missing the translation for your language of choice, please let us know too.

In addition, feedback and help to polish the desktop (menus, artwork, starters, etc.) is appreciated. We would like to ship a nice and handy KDE4 desktop targeted for schools out of the box.

The other profiles should be installable, but there is a lot more work left to be done before they are ready, so do not expect to much.

Changes compared to the lenny based version

• Everything from Debian Squeeze
  • Desktop environment KDE 4.4 => the new KDE desktop in combination with some new artwork
  • Web browser Iceweasel 3.5
  • OpenOffice.org 3.2
  • Educational toolbox GCompris 9.3
  • Music creator Rosegarden 10.04.2
  • Image editor Gimp 2.6.10
  • Virtual universe Celestia 1.6.0
  • Virtual stargazer Stellarium 0.10.4
  • 3D modeler Blender 2.49.2 (new application)
  • Video editor Kdenlive 0.7.7 (new application)
• Now using Kerberos for password checking (migration not finished). Enabled for:
  • PAM
  • LDAP
  • IMAP
  • SMTP (sender verification)
• New experimental roaming workstation profile for laptops.
• Show welcome page to users when they first log in. The URL is fetched from LDAP.
• New LXDE desktop option, in addition to KDE (default) and Gnome.
• General cleanup (not finished)

The following features are not working as they should

• No web based administration tool for creating users and groups. The scripts ldap-createuser-krb and ldap-add-user-to-group can be used for testing.
• DVD installs are missing debian-installer images for the PXE boot, and do not set up the PXE menu on eth0 because of this. LTSP clients should still boot from eth1 on thin client servers.
• The restructured KDE menu is not implemented.
• The LDAP server setup need to be reviewed for security.
• The LDAP directory structure need to be reworked.
• Different sets of packages are installed when using the DVD and the netinst CD. More packages are installed using the netinst CD.
• The jackd package fail to install. This is believed to be caused by some ongoing transition, and hopefully should be solved soon. The jackd1 package can be installed manually for those that need it.
• Some packages lack translations. See http://wiki.debian.org/DebianEdu/Status/Squeeze for updated status, and help out with translations.

To download this multiarch netinstall release you can use

• ftp://ftp.skolelinux.org/skolelinux-cd/squeeze-alpha/debian-edu-6.0.0+edua0-CD.iso
• http://ftp.skolelinux.org/skolelinux-cd/squeeze-alpha/debian-edu-6.0.0+edua0-CD.iso
• rsync -avzP ftp.skolelinux.org::skolelinux-cd/squeeze-alpha/debian-edu-6.0.0+edua0-CD.iso

To download this multiarch dvd release you can use

• ftp://ftp.skolelinux.org/skolelinux-cd/squeeze-alpha/debian-edu-6.0.0+edua0-DVD.iso
• http://ftp.skolelinux.org/skolelinux-cd/squeeze-alpha/debian-edu-6.0.0+edua0-DVD.iso
• rsync -avzP ftp.skolelinux.org::skolelinux-cd/squeeze-alpha/debian-edu-6.0.0+edua0-DVD.iso

There is no source DVD available yet. It will be prepared when we get closer to the final release.

The MD5SUM of these images are

• 3dbf45d59f42a53518b6e3c9ec3b5eb6 debian-edu-6.0.0+edua0-CD.iso
• 22f2cbfce281d1c6e478be452638675d debian-edu-6.0.0+edua0-DVD.iso

The SHA1SUM of these images are

• c53d1b69b40cf37cd27aefaf33f6f6a3821bedf0 debian-edu-6.0.0+edua0-CD.iso
• 2ec29d7db676d59d32197b05c277ffe16348376c debian-edu-6.0.0+edua0-DVD.iso

How to report bugs: http://wiki.debian.org/DebianEdu/HowTo/ReportBugsInBugzilla

Please direct replies to debian-edu@lists.debian.org

I discovered this while doing automated testing of upgrades from Debian Lenny to Squeeze. A few packages in Debian still got circular dependencies, and it is often claimed that apt and aptitude should be able to handle this just fine, but some times these dependency loops causes apt to fail.

An example is from todays upgrade of KDE using aptitude. In it, a bug in kdebase-workspace-data causes perl-modules to fail to upgrade. The cause is simple. If a package fail to unpack, then only part of packages with the circular dependency might end up being unpacked when unpacking aborts, and the ones already unpacked will fail to configure in the recovery phase because its dependencies are unavailable.

In this log, the problem manifest itself with this error:

dpkg: dependency problems prevent configuration of perl-modules:
 perl-modules depends on perl (>= 5.10.1-1); however:
  Version of perl on system is 5.10.0-19lenny2.
dpkg: error processing perl-modules (--configure):
 dependency problems - leaving unconfigured

The perl/perl-modules circular dependency is already reported as a bug, and will hopefully be solved as soon as possible, but it is not the only one, and each one of these loops in the dependency tree can cause similar failures. Of course, they only occur when there are bugs in other packages causing the unpacking to fail, but it is rather nasty when the failure of one package causes the problem to become worse because of dependency loops.

Thanks to the tireless effort by Bill Allombert, the number of circular dependencies left in Debian is dropping, and perhaps it will reach zero one day. :)

Todays testing also exposed a bug in update-notifier and different behaviour between apt-get and aptitude, the latter possibly caused by some circular dependency. Reported both to BTS to try to get someone to look at it.