Petter Reinholdtsen

Entries from May 2010.

Parallellized boot seem to hold up well in Debian/testing
27th May 2010

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:

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.

Tags: bootsystem, debian, debian edu, english.
More flexible firmware handling in debian-installer
22nd May 2010

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

Tags: debian, debian edu, english.
Magnetstripeinnhold i billetter fra Flytoget og Hurtigruten
21st May 2010

For en stund tilbake kjøpte jeg en magnetkortleser for å kunne titte på hva som er skrevet inn på magnetstripene til ulike kort. Har ikke hatt tid til å analysere mange kort så langt, men tenkte jeg skulle dele innholdet på to kort med mine lesere.

For noen dager siden tok jeg flyet til Harstad og Hurtigruten til Bergen. Flytoget fra Oslo S til flyplassen ga meg en billett med magnetstripe. Påtrykket finner jeg følgende informasjon:

Flytoget Airport Express Train

Fra - Til        : Oslo Sentralstasjon
Kategori         : Voksen
Pris             : Nok 170,00
Herav mva. 8,00% : NOK 12,59
Betaling         : Kontant
Til - Fra        : Oslo Lufthavn
Utstedt:         : 08.05.10
Gyldig Fra-Til   : 08.05.10-07.11.10
Billetttype      : Enkeltbillett


På selve magnetstripen er innholdet ;E?+900120011=23250996541068112619257138248441708433322932704083389389062603279671261502492655?. Aner ikke hva innholdet representerer, og det er lite overlapp mellom det jeg ser trykket på billetten og det jeg ser av tegn i magnetstripen. Håper det betyr at de bruker kryptografiske metoder for å gjøre det vanskelig å forfalske billetter.

Den andre billetten er fra Hurtigruten, der jeg mistenker at strekkoden på fronten er mer brukt enn magnetstripen (det var i hvert fall den biten vi stakk inn i dørlåsen).

Påtrykket forsiden er følgende:

Romnummer 727
Bookingno: SAX69   0742193
Dep: 09.05.2010 Arr: 12.05.2010
Lugar fra Risøyhamn
Kost: FRO=4

På selve magnetstripen er innholdet ;1316010007421930=00000000000000000000?+E?. Heller ikke her ser jeg mye korrespondanse mellom påtrykk og magnetstripe.

Tags: norsk, nuug, sikkerhet.
Pieces of the roaming laptop puzzle in Debian
19th May 2010

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

Tags: debian edu, english, nuug.
Parallellized boot is now the default in Debian/unstable
14th May 2010

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:


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.

Tags: bootsystem, debian, debian edu, english.
Sitesummary tip: Listing MAC address of all clients
14th May 2010

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.

Tags: debian, debian edu, english, sitesummary.
systemd, an interesting alternative to upstart
13th May 2010

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.

Tags: bootsystem, debian, english, nuug.
Parallellizing the boot in Debian Squeeze - ready for wider testing
6th May 2010

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:


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.

Tags: bootsystem, debian, english.
Forcing new users to change their password on first login
2nd May 2010

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

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

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

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.

Tags: debian edu, english, nuug, sikkerhet.

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