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5 <title>Petter Reinholdtsen
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14 <a href=
"http://people.skolelinux.org/pere/blog/">Petter Reinholdtsen
</a>
23 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/Autodetecting_Client_setup_for_roaming_workstations_in_Debian_Edu.html">Autodetecting Client setup for roaming workstations in Debian Edu
</a></div>
24 <div class=
"date">2010-
08-
07 14:
45</div>
27 <a href=
"http://people.skolelinux.org/pere/blog/Debian_Edu_roaming_workstation___at_the_university_of_Oslo.html">tried
28 to install
</a> a Roaming workation profile from Debian Edu/Squeeze
29 while on the university network here at the University of Oslo, and
30 noticed how much had to change to get it operational using the
31 university infrastructure. It was fairly easy, but it occured to me
32 that Debian Edu would improve a lot if I could get the client to
33 connect without any changes at all, and thus let the client configure
34 itself during installation and first boot to use the infrastructure
35 around it. Now I am a huge step further along that road.
</p>
37 <p>With our current squeeze-test packages, I can select the roaming
38 workstation profile and get a working laptop connecting to the
39 university LDAP server for user and group and our active directory
40 servers for Kerberos authentication. All this without any
41 configuration at all during installation. My users home directory got
42 a bookmark in the KDE menu to mount it via SMB, with the correct URL.
43 In short, openldap and sssd is correctly configured. In addition to
44 this, the client look for http://wpad/wpad.dat to configure a web
45 proxy, and when it fail to find it no proxy settings are stored in
46 /etc/environment and /etc/apt/apt.conf. Iceweasel and KDE is
47 configured to look for the same wpad configuration and also do not use
48 a proxy when at the university network. If the machine is moved to a
49 network with such wpad setup, it would automatically use it when DHCP
50 gave it a IP address.
</p>
52 <p>The LDAP server is located using DNS, by first looking for the DNS
53 entry ldap.$domain. If this do not exist, it look for the
54 _ldap._tcp.$domain SRV records and use the first one as the LDAP
55 server. Next, it connects to the LDAP server and search all
56 namingContexts entries for posixAccount or posixGroup objects, and
57 pick the first one as the LDAP base. For Kerberos, a similar
58 algorithm is used to locate the LDAP server, and the realm is the
59 uppercase version of $domain.
</p>
61 <p>So, what is not working, you might ask. SMB mounting my home
62 directory do not work. No idea why, but suspected the incorrect
63 Kerberos settings in /etc/krb5.conf and /etc/samba/smb.conf might be
64 the cause. These are not properly configured during installation, and
65 had to be hand-edited to get the correct Kerberos realm and server,
66 but SMB mounting still do not work. :(
</p>
68 <p>With this automatic configuration in place, I expect a Debian Edu
69 roaming profile installation would be able to automatically detect and
70 connect to any site using LDAP and Kerberos for NSS directory and PAM
71 authentication. It should also work out of the box in a Active
72 Directory environment providing posixAccount and posixGroup objects
73 with UID and GID values.
</p>
75 <p>If you want to help out with implementing these things for Debian
76 Edu, please contact us on debian-edu@lists.debian.org.
</p>
82 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>.
86 <div class=
"padding"></div>
89 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/Debian_Edu_roaming_workstation___at_the_university_of_Oslo.html">Debian Edu roaming workstation - at the university of Oslo
</a></div>
90 <div class=
"date">2010-
08-
03 23:
30</div>
92 <p>The new roaming workstation profile in Debian Edu/Squeeze is fairly
93 similar to the laptop setup am I working on using Ubuntu for the
94 University of Oslo, and just for the heck of it, I tested today how
95 hard it would be to integrate that profile into the university
96 infrastructure. In this case, it is the university LDAP server,
97 Active Directory Kerberos server and SMB mounting from the Netapp file
100 <p>I was pleasantly surprised that the only three files needed to be
101 changed (/etc/sssd/sssd.conf, /etc/ldap.conf and
102 /etc/mklocaluser.d/
20-debian-edu-config) and one file had to be added
103 (/usr/share/perl5/Debian/Edu_Local.pm), to get the client working.
104 Most of the changes were to get the client to use the university LDAP
105 for NSS and Kerberos server for PAM, but one was to change a hard
106 coded DNS domain name in the mklocaluser hook from .intern to
109 <p>This testing was so encouraging, that I went ahead and adjusted the
110 Debian Edu scripts and setup in subversion to centralise the roaming
111 workstation setup a bit more and avoid the hardcoded DNS domain name,
112 so that when I test this tomorrow, I expect to get away with modifying
113 only /etc/sssd/sssd.conf and /etc/ldap.conf to get it to use the
114 university servers.
</p>
116 <p>My goal is to get the clients to have no hardcoded settings and
117 fetch all their initial setup during installation and first boot, to
118 allow them to be inserted also into environments where the default
119 setup in Debian Edu has been changed or as with the university, where
120 the environment is different but provides the protocols Debian Edu
127 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>.
131 <div class=
"padding"></div>
134 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/Circular_package_dependencies_harms_apt_recovery.html">Circular package dependencies harms apt recovery
</a></div>
135 <div class=
"date">2010-
07-
27 23:
50</div>
137 <p>I discovered this while doing
138 <a href=
"http://people.skolelinux.org/pere/blog/Automatic_upgrade_testing_from_Lenny_to_Squeeze.html">automated
139 testing of upgrades from Debian Lenny to Squeeze
</a>. A few packages
140 in Debian still got circular dependencies, and it is often claimed
141 that apt and aptitude should be able to handle this just fine, but
142 some times these dependency loops causes apt to fail.
</p>
144 <p>An example is from todays
145 <a href=
"http://people.skolelinux.org/~pere/debian-upgrade-testing//test-20100727-lenny-squeeze-kde-aptitude.txt">upgrade
146 of KDE using aptitude
</a>. In it, a bug in kdebase-workspace-data
147 causes perl-modules to fail to upgrade. The cause is simple. If a
148 package fail to unpack, then only part of packages with the circular
149 dependency might end up being unpacked when unpacking aborts, and the
150 ones already unpacked will fail to configure in the recovery phase
151 because its dependencies are unavailable.
</p>
153 <p>In this log, the problem manifest itself with this error:
</p>
156 dpkg: dependency problems prevent configuration of perl-modules:
157 perl-modules depends on perl (
>=
5.10.1-
1); however:
158 Version of perl on system is
5.10.0-
19lenny
2.
159 dpkg: error processing perl-modules (--configure):
160 dependency problems - leaving unconfigured
163 <p>The perl/perl-modules circular dependency is already
164 <a href=
"http://bugs.debian.org/527917">reported as a bug
</a>, and will
165 hopefully be solved as soon as possible, but it is not the only one,
166 and each one of these loops in the dependency tree can cause similar
167 failures. Of course, they only occur when there are bugs in other
168 packages causing the unpacking to fail, but it is rather nasty when
169 the failure of one package causes the problem to become worse because
170 of dependency loops.
</p>
173 <a href=
"http://lists.debian.org/debian-devel/2010/06/msg00116.html">the
174 tireless effort by Bill Allombert
</a>, the number of circular
176 <a href=
"http://debian.semistable.com/debgraph.out.html">left in Debian
177 is dropping
</a>, and perhaps it will reach zero one day. :)
</p>
179 <p>Todays testing also exposed a bug in
180 <a href=
"http://bugs.debian.org/590605">update-notifier
</a> and
181 <a href=
"http://bugs.debian.org/590604">different behaviour
</a> between
182 apt-get and aptitude, the latter possibly caused by some circular
183 dependency. Reported both to BTS to try to get someone to look at
190 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian">debian
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>.
194 <div class=
"padding"></div>
197 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/First_Debian_Edu_test_release__alpha0__based_on_Squeeze_is_released.html">First Debian Edu test release (alpha0) based on Squeeze is released
</a></div>
198 <div class=
"date">2010-
07-
27 17:
45</div>
200 <p>I just posted this announcement culminating several months of work
201 with the next Debian Edu release. Not nearly done, but one major step
205 <p>This is the first test release based on Squeeze. The focus of this
206 release is to test the user application selection. To have a look,
207 install the standalone profile and let the developers know if the set
208 of installed packages i.e. applications should be modified. If some
209 user application is missing, or if there are some applications that no
210 longer make sense to be included in Debian Edu, please let us know.
211 Also, if a useful application is missing the translation for your
212 language of choice, please let us know too.
</p>
214 <p>In addition, feedback and help to polish the desktop (menus,
215 artwork, starters, etc.) is appreciated. We would like to ship a nice
216 and handy KDE4 desktop targeted for schools out of the box.
</p>
218 <p>The other profiles should be installable, but there is a lot more
219 work left to be done before they are ready, so do not expect to
222 <p>Changes compared to the lenny based version
</p>
225 <li>Everything from Debian Squeeze
227 <li>Desktop environment KDE
4.4 =
> the new KDE desktop in
228 combination with some new artwork
229 <li>Web browser Iceweasel
3.5
230 <li>OpenOffice.org
3.2
231 <li>Educational toolbox GCompris
9.3
232 <li>Music creator Rosegarden
10.04.2
233 <li>Image editor Gimp
2.6.10
234 <li>Virtual universe Celestia
1.6.0
235 <li>Virtual stargazer Stellarium
0.10.4
236 <li>3D modeler Blender
2.49.2 (new application)
237 <li>Video editor Kdenlive
0.7.7 (new application)
239 <li>Now using Kerberos for password checking (migration not finished).
245 <li>SMTP (sender verification)
248 <li>New experimental roaming workstation profile for laptops.
</li>
249 <li>Show welcome page to users when they first log in. The URL is
250 fetched from LDAP.
</li>
251 <li>New LXDE desktop option, in addition to KDE (default) and Gnome.
</li>
252 <li>General cleanup (not finished)
</li>
254 <p>The following features are not working as they should
</p>
257 <li>No web based administration tool for creating users and groups. The
258 scripts ldap-createuser-krb and ldap-add-user-to-group can be used
260 <li>DVD installs are missing debian-installer images for the PXE boot,
261 and do not set up the PXE menu on eth0 because of this. LTSP
262 clients should still boot from eth1 on thin client servers.
</li>
263 <li>The restructured KDE menu is not implemented.
</li>
264 <li>The LDAP server setup need to be reviewed for security.
</li>
265 <li>The LDAP directory structure need to be reworked.
</li>
266 <li>Different sets of packages are installed when using the DVD and the
267 netinst CD. More packages are installed using the netinst CD.
</li>
268 <li>The jackd package fail to install. This is believed to be caused by
269 some ongoing transition, and hopefully should be solved soon. The
270 jackd1 package can be installed manually for those that need it.
</li>
271 <li>Some packages lack translations. See
272 http://wiki.debian.org/DebianEdu/Status/Squeeze for updated status,
273 and help out with translations.
</li>
276 <p>To download this multiarch netinstall release you can use
</p>
279 <li><a href=
"ftp://ftp.skolelinux.org/skolelinux-cd/squeeze-alpha/debian-edu-6.0.0+edua0-CD.iso">ftp://ftp.skolelinux.org/skolelinux-cd/squeeze-alpha/debian-edu-
6.0.0+edua0-CD.iso
</a></li>
280 <li><a href=
"http://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
</a></li>
281 <li>rsync -avzP ftp.skolelinux.org::skolelinux-cd/squeeze-alpha/debian-edu-
6.0.0+edua0-CD.iso
</li>
283 <p>To download this multiarch dvd release you can use
</p>
286 <li><a href=
"ftp://ftp.skolelinux.org/skolelinux-cd/squeeze-alpha/debian-edu-6.0.0+edua0-DVD.iso">ftp://ftp.skolelinux.org/skolelinux-cd/squeeze-alpha/debian-edu-
6.0.0+edua0-DVD.iso
</a></li>
287 <li><a href=
"http://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
</a></li>
288 <li>rsync -avzP ftp.skolelinux.org::skolelinux-cd/squeeze-alpha/debian-edu-
6.0.0+edua0-DVD.iso
</li>
291 <p>There is no source DVD available yet. It will be prepared when we
292 get closer to the final release.
</p>
294 <p>The MD5SUM of these images are
</p>
297 <li>3dbf45d59f42a53518b6e3c9ec3b5eb6 debian-edu-
6.0.0+edua0-CD.iso
</li>
298 <li>22f2cbfce281d1c6e478be452638675d debian-edu-
6.0.0+edua0-DVD.iso
</li>
301 <p>The SHA1SUM of these images are
</p>
303 <li>c53d1b69b40cf37cd27aefaf33f6f6a3821bedf0 debian-edu-
6.0.0+edua0-CD.iso
</li>
304 <li>2ec29d7db676d59d32197b05c277ffe16348376c debian-edu-
6.0.0+edua0-DVD.iso
</li>
306 <p>How to report bugs:
307 http://wiki.debian.org/DebianEdu/HowTo/ReportBugsInBugzilla
</p>
309 <p>Please direct replies to debian-edu@lists.debian.org
</p>
316 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>.
320 <div class=
"padding"></div>
323 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/One_step_closer_to_single_signon_in_Debian_Edu.html">One step closer to single signon in Debian Edu
</a></div>
324 <div class=
"date">2010-
07-
25 10:
00</div>
326 <p>The last few months me and the other Debian Edu developers have
327 been working hard to get the Debian/Squeeze based version of Debian
328 Edu/Skolelinux into shape. This future version will use Kerberos for
329 authentication, and services are slowly migrated to single signon,
330 getting rid of password questions one at the time.
</p>
332 <p>It will also feature a roaming workstation profile with local home
333 directory, for laptops that are only some times on the Skolelinux
334 network, and for this profile a shortcut is created in Gnome and KDE
335 to gain access to the users home directory on the file server. This
336 shortcut uses SMB at the moment, and yesterday I had time to test if
337 SMB mounting had started working in KDE after we added the cifs-utils
338 package. I was pleasantly surprised how well it worked.
</p>
340 <p>Thanks to the recent changes to our samba configuration to get it
341 to use Kerberos for authentication, there were no question about user
342 password when mounting the SMB volume. A simple click on the shortcut
343 in the KDE menu, and a window with the home directory popped
346 <p>One step closer to a single signon solution out of the box in
347 Debian Edu. We already had PAM, LDAP, IMAP and SMTP in place, and now
348 also Samba. Next step is Cups and hopefully also NFS.
</p>
350 <p>We had planned a alpha0 release of Debian Edu for today, but thanks
351 to the autobuilder administrators for some architectures being slow to
352 sign packages, we are still missing the fixed LTSP package we need for
353 the release. It was uploaded three days ago with urgency=high, and if
354 it had entered testing yesterday we would have been able to test it in
355 time for a alpha0 release today. As the binaries for ia64 and powerpc
356 still not uploaded to the Debian archive, we need to delay the alpha
357 release another day.
</p>
359 <p>If you want to help out with implementing Kerberos for Debian Edu,
360 please contact us on debian-edu@lists.debian.org.
</p>
366 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet
</a>.
370 <div class=
"padding"></div>
373 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/Digitale_restriksjonsmekanismer_fikk_meg_til____slutte____kj__pe_musikk.html">Digitale restriksjonsmekanismer fikk meg til å slutte å kjøpe musikk
</a></div>
374 <div class=
"date">2010-
07-
22 23:
50</div>
376 <p>For mange år siden slutte jeg å kjøpe musikk-CDer. Årsaken var at
377 musikkbransjen var godt i gang med å selge platene sine med DRM som
378 gjorde at jeg ikke fikk spilt av musikken jeg kjøpte på utstyret jeg
379 hadde tilgjengelig, dvs. min datamaskin. Det var umulig å se på en
380 plate om den var ødelagt eller ikke, og jeg hadde jo allerede en
381 anseelig samling med plater, så jeg bestemme meg for å slutte å gi
382 penger til en bransje som åpenbart ikke respekterte meg.
</p>
384 <p>Jeg har mange titalls dager med musikk på CD i dag. Det meste er
385 lagt i et stort arkiv som kan spilles av fra husets datamaskiner (har
386 ikke rukket rippe alt). Jeg ser dermed ikke behovet for å skaffe mer
387 musikk. De fleste av mine favoritter er i hus, og jeg er dermed godt
390 <p>Hvis musikkbransjen ønsker mine penger, så må de demonstrere at de
391 setter pris på meg som kunde, og ikke skremme meg bort med DRM og
392 antydninger om at kundene er kriminelle.
</p>
394 <p>Filmbransjen er like ille, men mens musikk gjerne varer lenge, er
395 filmer mer ferskvare. Har dermed ikke helt sluttet å kjøpe filmer, men
396 holder meg til DVD-filmer som kan spilles av på mine Linuxbokser.
397 Kommer neppe til å ta i bruk Blueray, og ei heller de nye DRM-greiene
398 «Ultraviolet» som be annonsert her om dagen.
</p>
404 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/fildeling">fildeling
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/norsk">norsk
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/opphavsrett">opphavsrett
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/personvern">personvern
</a>.
408 <div class=
"padding"></div>
411 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/OpenStreetmap_one_step_closer_to_having_routing_on_its_front_page.html">OpenStreetmap one step closer to having routing on its front page
</a></div>
412 <div class=
"date">2010-
07-
18 16:
45</div>
415 <a href=
"http://feedproxy.google.com/~r/Opengeodata/~3/wUTCzDZk3lc/project-of-the-week-which-way-home">todays
416 opengeodata blog entry
</a>, I just discovered that the
417 OpenStreetmap.org site have gotten
418 <a href=
"http://nroets.dev.openstreetmap.org/demo/index.html?layers=B000FTFTT">support
419 for calculating routes
</a>. The support is still experimental and
420 only available from the development server, until more experience is
421 gathered on the user interface and any scalability issues.
</p>
423 <p>Earlier, the routing I knew about using the OpenStreetmap.org data
424 was provided by
<a href=
"http://maps.cloudmade.com/">Cloudmade
</a>,
425 but having it on the main page is required to make everyone aware of
426 the issue. I've had people reject Openstreetmap.org as a viable
427 alternative for them because the front page lacked routing support,
428 and I hope their needs will be catered for when routing show up on the
429 www.openstreetmap.org front page.
</p>
435 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/kart">kart
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/web">web
</a>.
439 <div class=
"padding"></div>
442 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/What_are_they_searching_for___PowerDNS_and_ISC_DHCP_in_LDAP.html">What are they searching for - PowerDNS and ISC DHCP in LDAP
</a></div>
443 <div class=
"date">2010-
07-
17 21:
00</div>
446 <a href=
"http://people.skolelinux.org/pere/blog/Time_for_new__LDAP_schemas_replacing_RFC_2307_.html">followup
</a>
448 <a href=
"http://people.skolelinux.org/pere/blog/Idea_for_a_change_to_LDAP_schemas_allowing_DNS_and_DHCP_info_to_be_combined_into_one_object.html">previous
450 <a href=
"http://people.skolelinux.org/pere/blog/Combining_PowerDNS_and_ISC_DHCP_LDAP_objects.html">merging
451 all
</a> the computer related LDAP objects in Debian Edu.
</p>
453 <p>As a step to try to see if it possible to merge the DNS and DHCP
454 LDAP objects, I have had a look at how the packages pdns-backend-ldap
455 and dhcp3-server-ldap in Debian use the LDAP server. The two
456 implementations are quite different in how they use LDAP.
</p>
458 To get this information, I started slapd with debugging enabled and
459 dumped the debug output to a file to get the LDAP searches performed
460 on a Debian Edu main-server. Here is a summary.
462 <p><strong>powerdns
</strong></p>
464 <a href=
"http://www.linuxnetworks.de/doc/index.php/PowerDNS_LDAP_Backend">Clues
465 on how to
</a> set up PowerDNS to use a LDAP backend is available on
468 <p>PowerDNS have two modes of operation using LDAP as its backend.
469 One "strict" mode where the forward and reverse DNS lookups are done
470 using the same LDAP objects, and a "tree" mode where the forward and
471 reverse entries are in two different subtrees in LDAP with a structure
472 based on the DNS names, as in tjener.intern and
473 2.2.0.10.in-addr.arpa.
</p>
475 <p>In tree mode, the server is set up to use a LDAP subtree as its
476 base, and uses a "base" scoped search for the DNS name by adding
477 "dc=tjener,dc=intern," to the base with a filter for
478 "(associateddomain=tjener.intern)" for the forward entry and
479 "dc=
2,dc=
2,dc=
0,dc=
10,dc=in-addr,dc=arpa," with a filter for
480 "(associateddomain=
2.2.0.10.in-addr.arpa)" for the reverse entry. For
481 forward entries, it is looking for attributes named dnsttl, arecord,
482 nsrecord, cnamerecord, soarecord, ptrrecord, hinforecord, mxrecord,
483 txtrecord, rprecord, afsdbrecord, keyrecord, aaaarecord, locrecord,
484 srvrecord, naptrrecord, kxrecord, certrecord, dsrecord, sshfprecord,
485 ipseckeyrecord, rrsigrecord, nsecrecord, dnskeyrecord, dhcidrecord,
486 spfrecord and modifytimestamp. For reverse entries it is looking for
487 the attributes dnsttl, arecord, nsrecord, cnamerecord, soarecord,
488 ptrrecord, hinforecord, mxrecord, txtrecord, rprecord, aaaarecord,
489 locrecord, srvrecord, naptrrecord and modifytimestamp. The equivalent
490 ldapsearch commands could look like this:
</p>
494 -b dc=tjener,dc=intern,ou=hosts,dc=skole,dc=skolelinux,dc=no \
495 -s base -x '(associateddomain=tjener.intern)' dNSTTL aRecord nSRecord \
496 cNAMERecord sOARecord pTRRecord hInfoRecord mXRecord tXTRecord \
497 rPRecord aFSDBRecord KeyRecord aAAARecord lOCRecord sRVRecord \
498 nAPTRRecord kXRecord certRecord dSRecord sSHFPRecord iPSecKeyRecord \
499 rRSIGRecord nSECRecord dNSKeyRecord dHCIDRecord sPFRecord modifyTimestamp
502 -b dc=
2,dc=
2,dc=
0,dc=
10,dc=in-addr,dc=arpa,ou=hosts,dc=skole,dc=skolelinux,dc=no \
503 -s base -x '(associateddomain=
2.2.0.10.in-addr.arpa)'
504 dnsttl, arecord, nsrecord, cnamerecord soarecord ptrrecord \
505 hinforecord mxrecord txtrecord rprecord aaaarecord locrecord \
506 srvrecord naptrrecord modifytimestamp
509 <p>In Debian Edu/Lenny, the PowerDNS tree mode is used with
510 ou=hosts,dc=skole,dc=skolelinux,dc=no as the base, and these are two
511 example LDAP objects used there. In addition to these objects, the
512 parent objects all th way up to ou=hosts,dc=skole,dc=skolelinux,dc=no
516 dn: dc=tjener,dc=intern,ou=hosts,dc=skole,dc=skolelinux,dc=no
518 objectclass: dnsdomain
519 objectclass: domainrelatedobject
522 associateddomain: tjener.intern
524 dn: dc=
2,dc=
2,dc=
0,dc=
10,dc=in-addr,dc=arpa,ou=hosts,dc=skole,dc=skolelinux,dc=no
526 objectclass: dnsdomain2
527 objectclass: domainrelatedobject
529 ptrrecord: tjener.intern
530 associateddomain:
2.2.0.10.in-addr.arpa
533 <p>In strict mode, the server behaves differently. When looking for
534 forward DNS entries, it is doing a "subtree" scoped search with the
535 same base as in the tree mode for a object with filter
536 "(associateddomain=tjener.intern)" and requests the attributes dnsttl,
537 arecord, nsrecord, cnamerecord, soarecord, ptrrecord, hinforecord,
538 mxrecord, txtrecord, rprecord, aaaarecord, locrecord, srvrecord,
539 naptrrecord and modifytimestamp. For reverse entires it also do a
540 subtree scoped search but this time the filter is "(arecord=
10.0.2.2)"
541 and the requested attributes are associateddomain, dnsttl and
542 modifytimestamp. In short, in strict mode the objects with ptrrecord
543 go away, and the arecord attribute in the forward object is used
546 <p>The forward and reverse searches can be simulated using ldapsearch
550 ldapsearch -h ldap -b ou=hosts,dc=skole,dc=skolelinux,dc=no -s sub -x \
551 '(associateddomain=tjener.intern)' dNSTTL aRecord nSRecord \
552 cNAMERecord sOARecord pTRRecord hInfoRecord mXRecord tXTRecord \
553 rPRecord aFSDBRecord KeyRecord aAAARecord lOCRecord sRVRecord \
554 nAPTRRecord kXRecord certRecord dSRecord sSHFPRecord iPSecKeyRecord \
555 rRSIGRecord nSECRecord dNSKeyRecord dHCIDRecord sPFRecord modifyTimestamp
557 ldapsearch -h ldap -b ou=hosts,dc=skole,dc=skolelinux,dc=no -s sub -x \
558 '(arecord=
10.0.2.2)' associateddomain dnsttl modifytimestamp
561 <p>In addition to the forward and reverse searches , there is also a
562 search for SOA records, which behave similar to the forward and
565 <p>A thing to note with the PowerDNS behaviour is that it do not
566 specify any objectclass names, and instead look for the attributes it
567 need to generate a DNS reply. This make it able to work with any
568 objectclass that provide the needed attributes.
</p>
570 <p>The attributes are normally provided in the cosine (RFC
1274) and
571 dnsdomain2 schemas. The latter is used for reverse entries like
572 ptrrecord and recent DNS additions like aaaarecord and srvrecord.
</p>
574 <p>In Debian Edu, we have created DNS objects using the object classes
575 dcobject (for dc), dnsdomain or dnsdomain2 (structural, for the DNS
576 attributes) and domainrelatedobject (for associatedDomain). The use
577 of structural object classes make it impossible to combine these
578 classes with the object classes used by DHCP.
</p>
580 <p>There are other schemas that could be used too, for example the
581 dnszone structural object class used by Gosa and bind-sdb for the DNS
582 attributes combined with the domainrelatedobject object class, but in
583 this case some unused attributes would have to be included as well
584 (zonename and relativedomainname).
</p>
586 <p>My proposal for Debian Edu would be to switch PowerDNS to strict
587 mode and not use any of the existing objectclasses (dnsdomain,
588 dnsdomain2 and dnszone) when one want to combine the DNS information
589 with DHCP information, and instead create a auxiliary object class
590 defined something like this (using the attributes defined for
591 dnsdomain and dnsdomain2 or dnszone):
</p>
594 objectclass ( some-oid NAME 'dnsDomainAux'
597 MAY ( ARecord $ MDRecord $ MXRecord $ NSRecord $ SOARecord $ CNAMERecord $
598 DNSTTL $ DNSClass $ PTRRecord $ HINFORecord $ MINFORecord $
599 TXTRecord $ SIGRecord $ KEYRecord $ AAAARecord $ LOCRecord $
600 NXTRecord $ SRVRecord $ NAPTRRecord $ KXRecord $ CERTRecord $
601 A6Record $ DNAMERecord
605 <p>This will allow any object to become a DNS entry when combined with
606 the domainrelatedobject object class, and allow any entity to include
607 all the attributes PowerDNS wants. I've sent an email to the PowerDNS
608 developers asking for their view on this schema and if they are
609 interested in providing such schema with PowerDNS, and I hope my
610 message will be accepted into their mailing list soon.
</p>
612 <p><strong>ISC dhcp
</strong></p>
614 <p>The DHCP server searches for specific objectclass and requests all
615 the object attributes, and then uses the attributes it want. This
616 make it harder to figure out exactly what attributes are used, but
617 thanks to the working example in Debian Edu I can at least get an idea
618 what is needed without having to read the source code.
</p>
620 <p>In the DHCP server configuration, the LDAP base to use and the
621 search filter to use to locate the correct dhcpServer entity is
622 stored. These are the relevant entries from
623 /etc/dhcp3/dhcpd.conf:
</p>
626 ldap-base-dn "dc=skole,dc=skolelinux,dc=no";
627 ldap-dhcp-server-cn "dhcp";
630 <p>The DHCP server uses this information to nest all the DHCP
631 configuration it need. The cn "dhcp" is located using the given LDAP
632 base and the filter "(&(objectClass=dhcpServer)(cn=dhcp))". The
633 search result is this entry:
</p>
636 dn: cn=dhcp,dc=skole,dc=skolelinux,dc=no
639 objectClass: dhcpServer
640 dhcpServiceDN: cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
643 <p>The content of the dhcpServiceDN attribute is next used to locate the
644 subtree with DHCP configuration. The DHCP configuration subtree base
645 is located using a base scope search with base "cn=DHCP
646 Config,dc=skole,dc=skolelinux,dc=no" and filter
647 "(&(objectClass=dhcpService)(|(dhcpPrimaryDN=cn=dhcp,dc=skole,dc=skolelinux,dc=no)(dhcpSecondaryDN=cn=dhcp,dc=skole,dc=skolelinux,dc=no)))".
648 The search result is this entry:
</p>
651 dn: cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
654 objectClass: dhcpService
655 objectClass: dhcpOptions
656 dhcpPrimaryDN: cn=dhcp, dc=skole,dc=skolelinux,dc=no
657 dhcpStatements: ddns-update-style none
658 dhcpStatements: authoritative
659 dhcpOption: smtp-server code
69 = array of ip-address
660 dhcpOption: www-server code
72 = array of ip-address
661 dhcpOption: wpad-url code
252 = text
664 <p>Next, the entire subtree is processed, one level at the time. When
665 all the DHCP configuration is loaded, it is ready to receive requests.
666 The subtree in Debian Edu contain objects with object classes
667 top/dhcpService/dhcpOptions, top/dhcpSharedNetwork/dhcpOptions,
668 top/dhcpSubnet, top/dhcpGroup and top/dhcpHost. These provide options
669 and information about netmasks, dynamic range etc. Leaving out the
670 details here because it is not relevant for the focus of my
671 investigation, which is to see if it is possible to merge dns and dhcp
672 related computer objects.
</p>
674 <p>When a DHCP request come in, LDAP is searched for the MAC address
675 of the client (
00:
00:
00:
00:
00:
00 in this example), using a subtree
676 scoped search with "cn=DHCP Config,dc=skole,dc=skolelinux,dc=no" as
677 the base and "(&(objectClass=dhcpHost)(dhcpHWAddress=ethernet
678 00:
00:
00:
00:
00:
00))" as the filter. This is what a host object look
682 dn: cn=hostname,cn=group1,cn=THINCLIENTS,cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
685 objectClass: dhcpHost
686 dhcpHWAddress: ethernet
00:
00:
00:
00:
00:
00
687 dhcpStatements: fixed-address hostname
690 <p>There is less flexiblity in the way LDAP searches are done here.
691 The object classes need to have fixed names, and the configuration
692 need to be stored in a fairly specific LDAP structure. On the
693 positive side, the invidiual dhcpHost entires can be anywhere without
694 the DN pointed to by the dhcpServer entries. The latter should make
695 it possible to group all host entries in a subtree next to the
696 configuration entries, and this subtree can also be shared with the
697 DNS server if the schema proposed above is combined with the dhcpHost
698 structural object class.
700 <p><strong>Conclusion
</strong></p>
702 <p>The PowerDNS implementation seem to be very flexible when it come
703 to which LDAP schemas to use. While its "tree" mode is rigid when it
704 come to the the LDAP structure, the "strict" mode is very flexible,
705 allowing DNS objects to be stored anywhere under the base cn specified
706 in the configuration.
</p>
708 <p>The DHCP implementation on the other hand is very inflexible, both
709 regarding which LDAP schemas to use and which LDAP structure to use.
710 I guess one could implement ones own schema, as long as the
711 objectclasses and attributes have the names used, but this do not
712 really help when the DHCP subtree need to have a fairly fixed
715 <p>Based on the observed behaviour, I suspect a LDAP structure like
716 this might work for Debian Edu:
</p>
720 cn=machine-info (dhcpService) - dhcpServiceDN points here
722 cn=dhcp-internal (dhcpSharedNetwork/dhcpOptions)
723 cn=
10.0.2.0 (dhcpSubnet)
724 cn=group1 (dhcpGroup/dhcpOptions)
725 cn=dhcp-thinclients (dhcpSharedNetwork/dhcpOptions)
726 cn=
192.168.0.0 (dhcpSubnet)
727 cn=group1 (dhcpGroup/dhcpOptions)
728 ou=machines - PowerDNS base points here
729 cn=hostname (dhcpHost/domainrelatedobject/dnsDomainAux)
732 <P>This is not tested yet. If the DHCP server require the dhcpHost
733 entries to be in the dhcpGroup subtrees, the entries can be stored
734 there instead of a common machines subtree, and the PowerDNS base
735 would have to be moved one level up to the machine-info subtree.
</p>
737 <p>The combined object under the machines subtree would look something
741 dn: dc=hostname,ou=machines,cn=machine-info,dc=skole,dc=skolelinux,dc=no
744 objectClass: dhcpHost
745 objectclass: domainrelatedobject
746 objectclass: dnsDomainAux
747 associateddomain: hostname.intern
749 dhcpHWAddress: ethernet
00:
00:
00:
00:
00:
00
750 dhcpStatements: fixed-address hostname.intern
753 </p>One could even add the LTSP configuration associated with a given
754 machine, as long as the required attributes are available in a
755 auxiliary object class.
</p>
761 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian">debian
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/ldap">ldap
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>.
765 <div class=
"padding"></div>
768 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/Combining_PowerDNS_and_ISC_DHCP_LDAP_objects.html">Combining PowerDNS and ISC DHCP LDAP objects
</a></div>
769 <div class=
"date">2010-
07-
14 23:
45</div>
771 <p>For a while now, I have wanted to find a way to change the DNS and
772 DHCP services in Debian Edu to use the same LDAP objects for a given
773 computer, to avoid the possibility of having a inconsistent state for
774 a computer in LDAP (as in DHCP but no DNS entry or the other way
775 around) and make it easier to add computers to LDAP.
</p>
777 <p>I've looked at how powerdns and dhcpd is using LDAP, and using this
778 information finally found a solution that seem to work.
</p>
780 <p>The old setup required three LDAP objects for a given computer.
781 One forward DNS entry, one reverse DNS entry and one DHCP entry. If
782 we switch powerdns to use its strict LDAP method (ldap-method=strict
783 in pdns-debian-edu.conf), the forward and reverse DNS entries are
784 merged into one while making it impossible to transfer the reverse map
785 to a slave DNS server.
</p>
787 <p>If we also replace the object class used to get the DNS related
788 attributes to one allowing these attributes to be combined with the
789 dhcphost object class, we can merge the DNS and DHCP entries into one.
790 I've written such object class in the dnsdomainaux.schema file (need
791 proper OIDs, but that is a minor issue), and tested the setup. It
794 <p>With this test setup in place, we can get away with one LDAP object
795 for both DNS and DHCP, and even the LTSP configuration I suggested in
796 an earlier email. The combined LDAP object will look something like
800 dn: cn=hostname,cn=group1,cn=THINCLIENTS,cn=DHCP Config,dc=skole,dc=skolelinux,dc=no
802 objectClass: dhcphost
803 objectclass: domainrelatedobject
804 objectclass: dnsdomainaux
805 associateddomain: hostname.intern
807 dhcphwaddress: ethernet
00:
00:
00:
00:
00:
00
808 dhcpstatements: fixed-address hostname
812 <p>The DNS server uses the associateddomain and arecord entries, while
813 the DHCP server uses the dhcphwaddress and dhcpstatements entries
814 before asking DNS to resolve the fixed-adddress. LTSP will use
815 dhcphwaddress or associateddomain and the ldapconfig* attributes.
</p>
817 <p>I am not yet sure if I can get the DHCP server to look for its
818 dhcphost in a different location, to allow us to put the objects
819 outside the "DHCP Config" subtree, but hope to figure out a way to do
820 that. If I can't figure out a way to do that, we can still get rid of
821 the hosts subtree and move all its content into the DHCP Config tree
822 (which probably should be renamed to be more related to the new
823 content. I suspect cn=dnsdhcp,ou=services or something like that
824 might be a good place to put it.
</p>
826 <p>If you want to help out with implementing this for Debian Edu,
827 please contact us on debian-edu@lists.debian.org.
</p>
833 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian">debian
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/ldap">ldap
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>.
837 <div class=
"padding"></div>
840 <div class=
"title"><a href=
"http://people.skolelinux.org/pere/blog/Idea_for_storing_LTSP_configuration_in_LDAP.html">Idea for storing LTSP configuration in LDAP
</a></div>
841 <div class=
"date">2010-
07-
11 22:
00</div>
843 <p>Vagrant mentioned on IRC today that ltsp_config now support
844 sourcing files from /usr/share/ltsp/ltsp_config.d/ on the thin
845 clients, and that this can be used to fetch configuration from LDAP if
846 Debian Edu choose to store configuration there.
</p>
848 <p>Armed with this information, I got inspired and wrote a test module
849 to get configuration from LDAP. The idea is to look up the MAC
850 address of the client in LDAP, and look for attributes on the form
851 ltspconfigsetting=value, and use this to export SETTING=value to the
854 <p>The goal is to be able to store the LTSP configuration attributes
855 in a "computer" LDAP object used by both DNS and DHCP, and thus
856 allowing us to store all information about a computer in one place.
</p>
858 <p>This is a untested draft implementation, and I welcome feedback on
859 this approach. A real LDAP schema for the ltspClientAux objectclass
860 need to be written. Comments, suggestions, etc?
</p>
863 # Store in /opt/ltsp/$arch/usr/share/ltsp/ltsp_config.d/ldap-config
865 # Fetch LTSP client settings from LDAP based on MAC address
867 # Uses ethernet address as stored in the dhcpHost objectclass using
868 # the dhcpHWAddress attribute or ethernet address stored in the
869 # ieee802Device objectclass with the macAddress attribute.
871 # This module is written to be schema agnostic, and only depend on the
872 # existence of attribute names.
874 # The LTSP configuration variables are saved directly using a
875 # ltspConfig prefix and uppercasing the rest of the attribute name.
876 # To set the SERVER variable, set the ltspConfigServer attribute.
878 # Some LDAP schema should be created with all the relevant
879 # configuration settings. Something like this should work:
881 # objectclass (
1.1.2.2 NAME 'ltspClientAux'
884 # MAY ( ltspConfigServer $ ltsConfigSound $ ... )
886 LDAPSERVER=$(debian-edu-ldapserver)
887 if [ "$LDAPSERVER" ] ; then
888 LDAPBASE=$(debian-edu-ldapserver -b)
889 for MAC in $(LANG=C ifconfig |grep -i hwaddr| awk '{print $
5}'|sort -u) ; do
890 filter="(|(dhcpHWAddress=ethernet $MAC)(macAddress=$MAC))"
891 ldapsearch -h "$LDAPSERVER" -b "$LDAPBASE" -v -x "$filter" | \
892 grep '^ltspConfig' | while read attr value ; do
893 # Remove prefix and convert to upper case
894 attr=$(echo $attr | sed 's/^ltspConfig//i' | tr a-z A-Z)
895 # bass value on to clients
896 eval "$attr=$value; export $attr"
902 <p>I'm not sure this shell construction will work, because I suspect
903 the while block might end up in a subshell causing the variables set
904 there to not show up in ltsp-config, but if that is the case I am sure
905 the code can be restructured to make sure the variables are passed on.
906 I expect that can be solved with some testing. :)
</p>
908 <p>If you want to help out with implementing this for Debian Edu,
909 please contact us on debian-edu@lists.debian.org.
</p>
911 <p>Update
2010-
07-
17: I am aware of another effort to store LTSP
912 configuration in LDAP that was created around year
2000 by
913 <a href=
"http://www.pcxperience.com/thinclient/documentation/ldap.html">PC
914 Xperience, Inc.,
2000</a>. I found its
915 <a href=
"http://people.redhat.com/alikins/ltsp/ldap/">files
</a> on a
916 personal home page over at redhat.com.
</p>
922 Tags:
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian">debian
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/english">english
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/ldap">ldap
</a>,
<a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug
</a>.
926 <div class=
"padding"></div>
928 <p style=
"text-align: right;"><a href=
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"http://people.skolelinux.org/pere/blog/xml.gif" alt=
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</a></li>
1029 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/ltsp">ltsp (
1)
</a></li>
1031 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/multimedia">multimedia (
5)
</a></li>
1033 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/norsk">norsk (
71)
</a></li>
1035 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/nuug">nuug (
90)
</a></li>
1037 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/opphavsrett">opphavsrett (
14)
</a></li>
1039 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/personvern">personvern (
14)
</a></li>
1041 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/reprap">reprap (
10)
</a></li>
1043 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/rss">rss (
1)
</a></li>
1045 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet (
10)
</a></li>
1047 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/sitesummary">sitesummary (
3)
</a></li>
1049 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/standard">standard (
13)
</a></li>
1051 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/stavekontroll">stavekontroll (
1)
</a></li>
1053 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/video">video (
10)
</a></li>
1055 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/vitenskap">vitenskap (
1)
</a></li>
1057 <li><a href=
"http://people.skolelinux.org/pere/blog/tags/web">web (
7)
</a></li>
1063 <p style=
"text-align: right">
1064 Created by
<a href=
"http://steve.org.uk/Software/chronicle">Chronicle v3.2
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