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   5   <title>Petter Reinholdtsen</title>
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  12  <div class="title">
  13   <h1>
  14        <a href="http://people.skolelinux.org/pere/blog/">Petter Reinholdtsen</a>
  15
  16   </h1>
  17
  18  </div>
  19
  20
  21
  22  <div class="entry">
  23   <div class="title"><a href="http://people.skolelinux.org/pere/blog/Skolelinux_i_Osloskolen.html">Skolelinux i Osloskolen</a></div>
  24   <div class="date">2010-08-26 22:25</div>
  25   <div class="body">
  26 <p>Denne høsten skal endelig alle Osloskolene få mulighet til å bruke
  27 <a href="http://www.skolelinux.org/">Skolelinux</a>.  Ny IT-løsning
  28 har vært rullet ut i noen måneder nå, og så vidt jeg fikk vite før
  29 sommeren skulle alle skoler ha nytt opplegg på plass før oppstart nå i
  30 høst.  På alle skolene skal en kunne velge ved installasjon om en skal
  31 ha Windows eller Skolelinux på maskinene, og en kan i tillegg
  32 PXE-boote maskinene over nett som tynne klienter eller diskløse
  33 arbeidsstasjoner. Jeg er spent på hvor mange skoler som velger å ta i
  34 bruk Skolelinux, og gleder meg til å se hvordan dette utvikler seg.
  35 Løsningen leveres av
  36 <a href="http://www.logica.no/">Logica</a> med
  37 <a href="http://www.slxdrift.no/">Skolelinux Drift AS</a> som
  38 underleverandør, og jeg har vært involvert i utviklingen av løsningen
  39 via Skolelinux Drift AS siden prosjektet starter.  Jeg synes det er
  40 fantastisk at Skolelinux er kommet så langt siden vi startet i 2001 at
  41 alle elevene i Osloskolene nå skal få mulighet til å bruke
  42 løsningen.  Jeg håper de vil sette pris på alle de
  43 <a href="http://www.skolelinux.no/linux-signpost/">fantastiske
  44 brukerprogrammene</a> som er tilgjengelig i Skolelinux.</p>
  45 </div>
  46   <div class="tags">
  47
  48
  49
  50    Tags: <a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu</a>, <a href="http://people.skolelinux.org/pere/blog/tags/norsk">norsk</a>.
  51
  52   </div>
  53  </div>
  54  <div class="padding"></div>
  55
  56  <div class="entry">
  57   <div class="title"><a href="http://people.skolelinux.org/pere/blog/Broken_umask_handling_with_sshfs.html">Broken umask handling with sshfs</a></div>
  58   <div class="date">2010-08-26 13:30</div>
  59   <div class="body">
  60 <p>My file system sematics program
  61 <a href="http://people.skolelinux.org/pere/blog/Testing_if_a_file_system_can_be_used_for_home_directories___.html">presented
  62 a few days ago</a> is very useful to verify that a file system can
  63 work as a unix home directory,and today I had to extend it a bit.  I'm
  64 looking into alternatives for home directory access here at the
  65 University of Oslo, and one of the options is sshfs.  My friend
  66 Finn-Arne mentioned a while back that they had used sshfs with Debian
  67 Edu, but stopped because of problems.  I asked today what the problems
  68 where, and he mentioned that sshfs failed to handle umask properly.
  69 Trying to detect the problem I wrote this addition to my fs testing
  70 script:</p>
  71
  72 <pre>
  73 mode_t touch_get_mode(const char *name, mode_t mode) {
  74   mode_t retval = 0;
  75   int fd = open(name, O_RDWR|O_CREAT|O_LARGEFILE, mode);
  76   if (-1 != fd) {
  77     unlink(name);
  78     struct stat statbuf;
  79     if (-1 != fstat(fd, &statbuf)) {
  80       retval = statbuf.st_mode & 0x1ff;
  81     }
  82     close(fd);
  83   }
  84   return retval;
  85 }
  86
  87 /* Try to detect problem discovered using sshfs */
  88 int test_umask(void) {
  89   printf("info: testing umask effect on file creation\n");
  90
  91   mode_t orig_umask = umask(000);
  92   mode_t newmode;
  93   if (0666 != (newmode = touch_get_mode("foobar", 0666))) {
  94     printf("  error: Wrong file mode %o when creating using mode 666 and umask 000\n",
  95            newmode);
  96   }
  97   umask(007);
  98   if (0660 != (newmode = touch_get_mode("foobar", 0666))) {
  99     printf("  error: Wrong file mode %o when creating using mode 666 and umask 007\n",
 100            newmode);
 101   }
 102
 103   umask (orig_umask);
 104   return 0;
 105 }
 106
 107 int main(int argc, char **argv) {
 108   [...]
 109   test_umask();
 110   return 0;
 111 }
 112 </pre>
 113
 114 <p>Sure enough.  On NFS to a netapp, I get this result:</p>
 115
 116 <pre>
 117 Testing POSIX/Unix sematics on file system
 118 info: testing symlink creation
 119 info: testing subdirectory creation
 120 info: testing fcntl locking
 121   Read-locking 1 byte from 1073741824
 122   Read-locking 510 byte from 1073741826
 123   Unlocking 1 byte from 1073741824
 124   Write-locking 1 byte from 1073741824
 125   Write-locking 510 byte from 1073741826
 126   Unlocking 2 byte from 1073741824
 127 info: testing umask effect on file creation
 128 </pre>
 129
 130 <p>When mounting the same directory using sshfs, I get this
 131 result:</p>
 132
 133 <pre>
 134 Testing POSIX/Unix sematics on file system
 135 info: testing symlink creation
 136 info: testing subdirectory creation
 137 info: testing fcntl locking
 138   Read-locking 1 byte from 1073741824
 139   Read-locking 510 byte from 1073741826
 140   Unlocking 1 byte from 1073741824
 141   Write-locking 1 byte from 1073741824
 142   Write-locking 510 byte from 1073741826
 143   Unlocking 2 byte from 1073741824
 144 info: testing umask effect on file creation
 145   error: Wrong file mode 644 when creating using mode 666 and umask 000
 146   error: Wrong file mode 640 when creating using mode 666 and umask 007
 147 </pre>
 148
 149 <p>So, I can conclude that sshfs is better than smb to a Netapp or a
 150 Windows server, but not good enough to be used as a home
 151 directory.</p>
 152
 153 <p>Update 2010-08-26: Reported the issue in
 154 <a href="http://bugs.debian.org/594498">BTS report #594498</a></p>
 155 </div>
 156   <div class="tags">
 157
 158
 159
 160    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>.
 161
 162   </div>
 163  </div>
 164  <div class="padding"></div>
 165
 166  <div class="entry">
 167   <div class="title"><a href="http://people.skolelinux.org/pere/blog/Elektronisk_stemmegiving_er_ikke_til____stole_p_____heller_ikke_i_Norge.html">Elektronisk stemmegiving er ikke til å stole på - heller ikke i Norge</a></div>
 168   <div class="date">2010-08-23 19:30</div>
 169   <div class="body">
 170 <p>I Norge pågår en prosess for å
 171 <a href="http://www.e-valg.dep.no/">innføre elektronisk
 172 stemmegiving</a> ved kommune- og stortingsvalg.  Dette skal
 173 introduseres i 2011.  Det er all grunn til å tro at valg i Norge ikke
 174 vil være til å stole på hvis dette blir gjennomført.  Da det hele var
 175 oppe til høring i 2006 forfattet jeg
 176 <a href="http://www.nuug.no/dokumenter/valg-horing-2006-09.pdf">en
 177 høringsuttalelse fra NUUG</a> (og EFN som hengte seg på) som skisserte
 178 hvilke punkter som må oppfylles for at en skal kunne stole på et valg,
 179 og elektronisk stemmegiving mangler flere av disse.  Elektronisk
 180 stemmegiving er for alle praktiske formål å putte ens stemme i en sort
 181 boks under andres kontroll, og satse på at de som har kontroll med
 182 boksen er til å stole på - uten at en har mulighet til å verifisere
 183 dette selv.  Det er ikke slik en gjennomfører demokratiske valg.</p>
 184
 185 <p>Da problemet er fundamentalt med hvordan elektronisk stemmegiving
 186 må fungere for at også ikke-krypografer skal kunne delta, har det vært
 187 mange rapporter om hvordan elektronisk stemmegiving har sviktet i land
 188 etter land.  En
 189 <a href="http://wiki.nuug.no/uttalelser/2006-elektronisk-stemmegiving">liten
 190 samling referanser</a> finnes på NUUGs wiki.  Den siste er fra India,
 191 der valgkomisjonen har valgt
 192 <a href="http://www.freedom-to-tinker.com/blog/jhalderm/electronic-voting-researcher-arrested-over-anonymous-source">å
 193 pusse politiet på en forsker</a> som har dokumentert svakheter i
 194 valgsystemet.</p>
 195
 196 <p>Her i Norge har en valgt en annen tilnærming, der en forsøker seg
 197 med teknobabbel for å få befolkningen til å tro at dette skal bli
 198 sikkert.  Husk, elektronisk stemmegiving underminerer de demokratiske
 199 valgene i Norge, og bør ikke innføres.</p>
 200
 201 <p>Den offentlige diskusjonen blir litt vanskelig av at media har
 202 valgt å kalle dette "evalg", som kan sies å både gjelde elektronisk
 203 opptelling av valget som Norge har gjort siden 60-tallet og som er en
 204 svært god ide, og elektronisk opptelling som er en svært dårlig ide.
 205 Diskusjonen gir ikke mening hvis en skal diskutere om en er for eller
 206 mot "evalg", og jeg forsøker derfor å være klar på at jeg snakker om
 207 elektronisk stemmegiving og unngå begrepet "evalg".</p>
 208 </div>
 209   <div class="tags">
 210
 211
 212
 213    Tags: <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/sikkerhet">sikkerhet</a>.
 214
 215   </div>
 216  </div>
 217  <div class="padding"></div>
 218
 219  <div class="entry">
 220   <div class="title"><a href="http://people.skolelinux.org/pere/blog/Robot__reis_deg___.html">Robot, reis deg...</a></div>
 221   <div class="date">2010-08-21 22:10</div>
 222   <div class="body">
 223 <p>I dag fikk jeg endelig tittet litt på mine nyinnkjøpte roboter, og
 224 har brukt noen timer til å google etter interessante referanser og
 225 aktuell kildekode for bruk på Linux.  Det mest lovende så langt er
 226 <a href="http://ispykee.toyz.org/">ispykee</a>, som har en
 227 BSD-lisensiert linux-daemon som står som mellomledd mellom roboter på
 228 lokalnettet og en sentral tjeneste der en iPhone kan koble seg opp for
 229 å fjernstyre roboten.  Linux-daemonen implementerer deler av
 230 protokollen som roboten forstår.  Etter å ha knotet litt med å oppnå
 231 kontakt med roboten (den oppretter et eget ad-hoc wifi-nett, så jeg
 232 måtte gå av mitt vanlige nett for å få kontakt), og kommet frem til at
 233 den lytter på IP-port 9000 og 9001, gikk jeg i gang med å finne ut
 234 hvordan jeg kunne snakke med roboten vha. disse portene.  Robotbiten
 235 av protokollen er publisert av produsenten med GPL-lisens, slik at det
 236 er mulig å se hvordan protokollen fungerer.  Det finnes en java-klient
 237 for Android som så ganske snasen ut, men fant ingen kildekode for
 238 denne.  Derimot hadde iphone-løsningen kildekode, så jeg tok
 239 utgangspunkt i den.</p>
 240
 241 <p>Daemonen ville i utgangspunktet forsøke å kontakte den sentrale
 242 tjenesten som iphone-programmet kobler seg til.  Jeg skrev dette om
 243 til i stedet å sette opp en nettverkstjeneste på min lokale maskin,
 244 som jeg kan koble meg opp til med telnet og gi kommandoer til roboten
 245 (act, forward, right, left, etc).  Det involverte i praksis å bytte ut
 246 socket()/connect() med socket()/bind()/listen()/accept() for å gjøre
 247 klienten om til en tjener.</p>
 248
 249 <p>Mens jeg har forsøkt å få roboten til å bevege seg har min samboer
 250 skrudd sammen resten av roboten for å få montert kamera og plastpynten
 251 (armer, plastfiber for lys).  Nå er det hele montert, og roboten er
 252 klar til bruk.  Må få flyttet den over til mitt vanlige trådløsnett
 253 før det blir praktisk, men de bitene av protokollen er ikke
 254 implementert i ispykee-daemonen, så der må jeg enten få tak i en mac
 255 eller en windows-maskin, eller implementere det selv.</p>
 256
 257 <p>Vi var tre som kjøpte slike roboter, og vi har blitt enige om å
 258 samle notater og referanser på <a
 259 href="http://wiki.nuug.no/grupper/robot/">NUUGs wiki</a>.  Ta en titt
 260 der hvis du er nysgjerrig.</p>
 261 </div>
 262   <div class="tags">
 263
 264
 265
 266    Tags: <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/robot">robot</a>.
 267
 268   </div>
 269  </div>
 270  <div class="padding"></div>
 271
 272  <div class="entry">
 273   <div class="title"><a href="http://people.skolelinux.org/pere/blog/2_Spykee_roboter_i_hus__n___skal_det_lekes.html">2 Spykee-roboter i hus, nå skal det lekes</a></div>
 274   <div class="date">2010-08-18 13:30</div>
 275   <div class="body">
 276 <p>Jeg kjøpte nettopp to
 277 <a href="http://www.spykee-robot.com/">Spykee</a>-roboter, for test og
 278 leking.  Kjøpte to da det var så billige, og gir meg mulighet til å
 279 eksperimentere uten å være veldig redd for å ødelegge alt ved å bytte
 280 ut firmware og slikt.  Oppdaget at lekebutikken på Bryn senter hadde
 281 en liten stabel på lager som de ikke hadde klart å selge ut etter
 282 fjorårets juleinnkjøp, og var villig til å selge for en femtedel av
 283 vanlig pris.  Jeg, Ronny og Jarle har skaffet oss restbeholdningen, og
 284 det blir morsomt å se hva vi får ut av dette.</p>
 285
 286 <p>Roboten har belter styrt av to motorer, kamera, høytaler, mikrofon
 287 og wifi-tilkobling.  Det hele styrt av en GPL-lisensiert databoks som
 288 jeg mistenker kjører linux.  Firmware-kildekoden ble visst publisert i
 289 mai.  Eneste utfordringen er at kontroller-programvaren kun finnes til
 290 Windows, men det må en kunne jobbe seg rundt når vi har kildekoden til
 291 firmwaren. :)</p>
 292
 293 <ul>
 294 <li><a href="http://en.wikipedia.org/wiki/Spykee">Wikipedia-oppføring</a></li>
 295 <li><a href=http://www.spykeeworld.com/spykee/US/freeSoftware.html">Nedlasting av firmware-kilden</a></li>
 296 <li><a href="http://wiki.nuug.no/grupper/robot">prosjektwiki hos NUUG</a></li>
 297 </ul>
 298 </div>
 299   <div class="tags">
 300
 301
 302
 303    Tags: <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/robot">robot</a>.
 304
 305   </div>
 306  </div>
 307  <div class="padding"></div>
 308
 309  <div class="entry">
 310   <div class="title"><a href="http://people.skolelinux.org/pere/blog/Rob_Weir__How_to_Crush_Dissent.html">Rob Weir: How to Crush Dissent</a></div>
 311   <div class="date">2010-08-15 22:20</div>
 312   <div class="body">
 313 <p>I found the notes from Rob Weir on
 314 <a href="http://feedproxy.google.com/~r/robweir/antic-atom/~3/VGb23-kta8c/how-to-crush-dissent.html">how
 315 to crush dissent</a> matching my own thoughts on the matter quite
 316 well.  Highly recommended for those wondering which road our society
 317 should go down.  In my view we have been heading the wrong way for a
 318 long time.</p>
 319 </div>
 320   <div class="tags">
 321
 322
 323
 324    Tags: <a href="http://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="http://people.skolelinux.org/pere/blog/tags/lenker">lenker</a>, <a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug</a>, <a href="http://people.skolelinux.org/pere/blog/tags/personvern">personvern</a>, <a href="http://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet</a>.
 325
 326   </div>
 327  </div>
 328  <div class="padding"></div>
 329
 330  <div class="entry">
 331   <div class="title"><a href="http://people.skolelinux.org/pere/blog/No_hardcoded_config_on_Debian_Edu_clients.html">No hardcoded config on Debian Edu clients</a></div>
 332   <div class="date">2010-08-09 20:15</div>
 333   <div class="body">
 334 <p>As reported earlier, the last few days I have looked at how Debian
 335 Edu clients are configured, and tried to get rid of all hardcoded
 336 configuration settings on the clients.  I believe the work to be
 337 mostly done, and the clients seem to work just fine with dynamically
 338 generated configuration.</p>
 339
 340 <p>What is the point, you might ask?  The point is to allow a Debian
 341 Edu desktop to integrate into an existing network infrastructure
 342 without any manual configuration.</p>
 343
 344 <p>This is what happens when installing a Debian Edu client here at
 345 the University of Oslo using PXE.  With the PXE installation, I am
 346 asked for language (Norwegian Bokmål), locality (Norway) and keyboard
 347 layout (no-latin1), Debian Edu profile (Roaming Workstation), if I
 348 accept to reformat the hard drive (yes), if I want to submit info to
 349 popcon.debian.org (no) and root password (secret).  After answering
 350 these questions, the installer goes ahead and does its thing, and
 351 after around 50 minutes it is done.  I press enter to finish the
 352 installation, and the machine reboots into KDE.  When the machine is
 353 ready and kdm asks for login information, I enter my university
 354 username and password, am told by kdm that a local home directory has
 355 been created and that I must log in again, and finally log in with the
 356 same username and password to the KDE 4.4 desktop.  At no point during
 357 this process did it ask for university specific settings, and all the
 358 required configuration was dynamically detected using information
 359 fetched via DHCP and DNS.  The roaming workstation is now ready for
 360 use.</p>
 361
 362 <p>How was this done, you might wonder?  First of all, here is the
 363 list of things that need to be configured on the client to get it
 364 working properly out of the box:</p>
 365
 366 <ul>
 367 <li>IP address/netmask and DNS server.</li>
 368 <li>Web proxy URL.</li>
 369 <li>LDAP server for NSS directory information (user, group, etc).</li>
 370 <li>Kerberos server for PAM password checking.</li>
 371 <li>SMB mount point to access the network home directory. (*)</li>
 372 <li>Central syslog server to send syslog messages to. (*)</li>
 373 <li>Sitesummary collector URL to submit info to central server. (*)</li>
 374 </ul>
 375
 376 <p>(Hm, did I forget anything?  Let me knew if I did.)</p>
 377
 378 <p>The points marked (*) are not required to be able to use the
 379 machine, but needed to provide central storage and allowing system
 380 administrators to track their machines.  Since yesterday, everything
 381 but the sitesummary collector URL is dynamically discovered at boot
 382 and installation time in the svn version of Debian Edu.</p>
 383
 384 <p>The IP and DNS setup is fetched during boot using DHCP as usual.
 385 When a DHCP update arrives, the proxy setup is updated by looking for
 386 http://wpat/wpad.dat and using the content of this WPAD file to
 387 configure the http and ftp proxy in /etc/environment and
 388 /etc/apt/apt.conf.  I decided to update the proxy setup using a DHCP
 389 hook to ensure that the client stops using the Debian Edu proxy when
 390 it is moved outside the Debian Edu network, and instead uses any local
 391 proxy present on the new network when it moves around.</p>
 392
 393 <p>The DNS names of the LDAP, Kerberos and syslog server and related
 394 configuration are generated using DNS information at boot.  First the
 395 installer looks for a host named ldap in the current DNS domain.  If
 396 not found, it looks for _ldap._tcp SRV records in DNS instead.  If an
 397 LDAP server is found, its root DSE entry is requested and the
 398 attributes namingContexts and defaultNamingContext are used to
 399 determine which LDAP base to use for NSS.  If there are several
 400 namingContexts attibutes and the defaultNamingContext is present, that
 401 LDAP subtree is used as the base.  If defaultNamingContext is missing,
 402 the subtrees listed as namingContexts are searched in sequence for any
 403 object with class posixAccount or posixGroup, and the first one with
 404 such an object is used as the LDAP base.  For Kerberos, a similar
 405 search is done by first looking for a host named kerberos, and then
 406 for the _kerberos._tcp SRV record.  I've been unable to find a way to
 407 look up the Kerberos realm, so for this the upper case string of the
 408 current DNS domain is used.</p>
 409
 410 <p>For the syslog server, the hosts syslog and loghost are searched
 411 for, and the _syslog._udp SRV record is consulted if no such host is
 412 found.  This algorithm works for both Debian Edu and the University of
 413 Oslo.  A similar strategy would work for locating the sitesummary
 414 server, but have not been implemented yet.  I decided to fetch and
 415 save these settings during installation, to make sure moving to a
 416 different network does not change the set of users being allowed to
 417 log in nor the passwords required to log in.  Usernames and passwords
 418 will be cached by sssd when the user logs in on the Debian Edu
 419 network, and will not change as the laptop move around.  For a
 420 non-roaming machine, there is no caching, but given that it is
 421 supposed to stay in place it should not matter much.  Perhaps we
 422 should switch those to use sssd too?</p>
 423
 424 <p>The user's SMB mount point for the network home directory is
 425 located when the user logs in for the first time.  The LDAP server is
 426 consulted to look for the user's LDAP object and the sambaHomePath
 427 attribute is used if found.  If it isn't found, the home directory
 428 path fetched from NSS is used instead.  Assuming the path is of the
 429 form /site/server/directory/username, the second part is looked up in
 430 DNS and used to generate a SMB URL of the form
 431 smb://server.domain/username.  This algorithm works for both Debian
 432 edu and the University of Oslo.  Perhaps there are better attributes
 433 to use or a better algorithm that works for more sites, but this will
 434 do for now. :)</p>
 435
 436 <p>This work should make it easier to integrate the Debian Edu clients
 437 into any LDAP/Kerberos infrastructure, and make the current setup even
 438 more flexible than before.  I suspect it will also work for thin
 439 client servers, allowing one to easily set up LTSP and hook it into a
 440 existing network infrastructure, but I have not had time to test this
 441 yet.</p>
 442
 443 <p>If you want to help out with implementing these things for Debian
 444 Edu, please contact us on debian-edu@lists.debian.org.</p>
 445
 446 <p>Update 2010-08-09: Simon Farnsworth gave me a heads-up on how to
 447 detect Kerberos realm from DNS, by looking for _kerberos TXT entries
 448 before falling back to the upper case DNS domain name.  Will have to
 449 implement it for Debian Edu. :)</p>
 450 </div>
 451   <div class="tags">
 452
 453
 454
 455    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>.
 456
 457   </div>
 458  </div>
 459  <div class="padding"></div>
 460
 461  <div class="entry">
 462   <div class="title"><a href="http://people.skolelinux.org/pere/blog/Testing_if_a_file_system_can_be_used_for_home_directories___.html">Testing if a file system can be used for home directories...</a></div>
 463   <div class="date">2010-08-08 21:20</div>
 464   <div class="body">
 465 <p>A few years ago, I was involved in a project planning to use
 466 Windows file servers as home directory servers for Debian
 467 Edu/Skolelinux machines.  This was thought to be no problem, as the
 468 access would be through the SMB network file system protocol, and we
 469 knew other sites used SMB with unix and samba as the file server to
 470 mount home directories without any problems.  But, after months of
 471 struggling, we had to conclude that our goal was impossible.</p>
 472
 473 <p>The reason is simply that while SMB can be used for home
 474 directories when the file server is Samba running on Unix, this only
 475 work because of Samba have some extensions and the fact that the
 476 underlying file system is a unix file system.  When using a Windows
 477 file server, the underlying file system do not have POSIX semantics,
 478 and several programs will fail if the users home directory where they
 479 want to store their configuration lack POSIX semantics.</p>
 480
 481 <p>As part of this work, I wrote a small C program I want to share
 482 with you all, to replicate a few of the problematic applications (like
 483 OpenOffice.org and GCompris) and see if the file system was working as
 484 it should.  If you find yourself in spooky file system land, it might
 485 help you find your way out again.  This is the fs-test.c source:</p>
 486
 487 <pre>
 488 /*
 489  * Some tests to check the file system sematics.  Used to verify that
 490  * CIFS from a windows server do not work properly as a linux home
 491  * directory.
 492  * License: GPL v2 or later
 493  *
 494  * needs libsqlite3-dev and build-essential installed
 495  * compile with: gcc -Wall -lsqlite3 -DTEST_SQLITE fs-test.c -o fs-test
 496 */
 497
 498 #define _FILE_OFFSET_BITS 64
 499 #define _LARGEFILE_SOURCE 1
 500 #define _LARGEFILE64_SOURCE 1
 501
 502 #define _GNU_SOURCE /* for asprintf() */
 503
 504 #include &lt;errno.h>
 505 #include &lt;fcntl.h>
 506 #include &lt;stdio.h>
 507 #include &lt;string.h>
 508 #include &lt;stdlib.h>
 509 #include &lt;sys/file.h>
 510 #include &lt;sys/stat.h>
 511 #include &lt;sys/types.h>
 512 #include &lt;unistd.h>
 513
 514 #ifdef TEST_SQLITE
 515 /*
 516  * Test sqlite open, as done by gcompris require the libsqlite3-dev
 517  * package and linking with -lsqlite3.  A more low level test is
 518  * below.
 519  * See also &lt;URL: http://www.sqlite.org./faq.html#q5 >.
 520  */
 521 #include &lt;sqlite3.h>
 522 #define CREATE_TABLE_USERS                                              \
 523   "CREATE TABLE users (user_id INT UNIQUE, login TEXT, lastname TEXT, firstname TEXT, birthdate TEXT, class_id INT ); "
 524 int test_sqlite_open(void) {
 525   char *zErrMsg;
 526   char *name = "testsqlite.db";
 527   sqlite3 *db=NULL;
 528   unlink(name);
 529   int rc = sqlite3_open(name, &db);
 530   if( rc ){
 531     printf("error: sqlite open of %s failed: %s\n", name, sqlite3_errmsg(db));
 532     sqlite3_close(db);
 533     return -1;
 534   }
 535
 536   /* create tables */
 537   rc = sqlite3_exec(db,CREATE_TABLE_USERS, NULL,  0, &zErrMsg);
 538   if( rc != SQLITE_OK ){
 539     printf("error: sqlite table create failed: %s\n", zErrMsg);
 540     sqlite3_close(db);
 541     return -1;
 542   }
 543   printf("info: sqlite worked\n");
 544   sqlite3_close(db);
 545   return 0;
 546 }
 547 #endif /* TEST_SQLITE */
 548
 549 /*
 550  * Demonstrate locking issue found in gcompris using sqlite3.  This
 551  * work with ext3, but not with cifs server on Windows 2003.  This is
 552  * done in the sqlite3 library.
 553  * See also
 554  * &lt;URL:http://www.cygwin.com/ml/cygwin/2001-08/msg00854.html> and the
 555  * POSIX specification
 556  * &lt;URL:http://www.opengroup.org/onlinepubs/009695399/functions/fcntl.html>.
 557  */
 558 int test_gcompris_locking(void) {
 559   struct flock fl;
 560   char *name = "testsqlite.db";
 561   unlink(name);
 562   int fd = open(name, O_RDWR|O_CREAT|O_LARGEFILE, 0644);
 563   printf("info: testing fcntl locking\n");
 564
 565   fl.l_whence = SEEK_SET;
 566   fl.l_pid    = getpid();
 567   printf("  Read-locking 1 byte from 1073741824");
 568   fl.l_start  = 1073741824;
 569   fl.l_len    = 1;
 570   fl.l_type   = F_RDLCK;
 571   if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
 572
 573   printf("  Read-locking 510 byte from 1073741826");
 574   fl.l_start  = 1073741826;
 575   fl.l_len    = 510;
 576   fl.l_type   = F_RDLCK;
 577   if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
 578
 579   printf("  Unlocking 1 byte from 1073741824");
 580   fl.l_start  = 1073741824;
 581   fl.l_len    = 1;
 582   fl.l_type   = F_UNLCK;
 583   if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
 584
 585   printf("  Write-locking 1 byte from 1073741824");
 586   fl.l_start  = 1073741824;
 587   fl.l_len    = 1;
 588   fl.l_type   = F_WRLCK;
 589   if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
 590
 591   printf("  Write-locking 510 byte from 1073741826");
 592   fl.l_start  = 1073741826;
 593   fl.l_len    = 510;
 594   if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
 595
 596   printf("  Unlocking 2 byte from 1073741824");
 597   fl.l_start  = 1073741824;
 598   fl.l_len    = 2;
 599   fl.l_type   = F_UNLCK;
 600   if (0 != fcntl(fd, F_SETLK, &fl) ) printf(" - error!\n"); else printf("\n");
 601
 602   close(fd);
 603   return 0;
 604 }
 605
 606 /*
 607  * Test if permissions of freshly created directories allow entries
 608  * below them.  This was a problem with OpenOffice.org and gcompris.
 609  * Mounting with option 'sync' seem to solve this problem while
 610  * slowing down file operations.
 611  */
 612 int test_subdirectory_creation(void) {
 613 #define LEVELS 5
 614   char *path = strdup("test");
 615   char *dirs[LEVELS];
 616   int level;
 617   printf("info: testing subdirectory creation\n");
 618   for (level = 0; level &lt; LEVELS; level++) {
 619     char *newpath = NULL;
 620     if (-1 == mkdir(path, 0777)) {
 621       printf("  error: Unable to create directory '%s': %s\n",
 622              path, strerror(errno));
 623       break;
 624     }
 625     asprintf(&newpath, "%s/%s", path, "test");
 626     free(path);
 627     path = newpath;
 628   }
 629   return 0;
 630 }
 631
 632 /*
 633  * Test if symlinks can be created.  This was a problem detected with
 634  * KDE.
 635  */
 636 int test_symlinks(void) {
 637   printf("info: testing symlink creation\n");
 638   unlink("symlink");
 639   if (-1 == symlink("file", "symlink"))
 640     printf("  error: Unable to create symlink\n");
 641   return 0;
 642 }
 643
 644 int main(int argc, char **argv) {
 645   printf("Testing POSIX/Unix sematics on file system\n");
 646   test_symlinks();
 647   test_subdirectory_creation();
 648 #ifdef TEST_SQLITE
 649   test_sqlite_open();
 650 #endif /* TEST_SQLITE */
 651   test_gcompris_locking();
 652   return 0;
 653 }
 654 </pre>
 655
 656 <p>When everything is working, it should print something like
 657 this:</p>
 658
 659 <pre>
 660 Testing POSIX/Unix sematics on file system
 661 info: testing symlink creation
 662 info: testing subdirectory creation
 663 info: sqlite worked
 664 info: testing fcntl locking
 665   Read-locking 1 byte from 1073741824
 666   Read-locking 510 byte from 1073741826
 667   Unlocking 1 byte from 1073741824
 668   Write-locking 1 byte from 1073741824
 669   Write-locking 510 byte from 1073741826
 670   Unlocking 2 byte from 1073741824
 671 </pre>
 672
 673 <p>I do not remember the exact details of the problems we saw, but one
 674 of them was with locking, where if I remember correctly, POSIX allow a
 675 read-only lock to be upgraded to a read-write lock without unlocking
 676 the read-only lock (while Windows do not).  Another was a bug in the
 677 CIFS/SMB client implementation in the Linux kernel where directory
 678 meta information would be wrong for a fraction of a second, making
 679 OpenOffice.org fail to create its deep directory tree because it was
 680 not allowed to create files in its freshly created directory.</p>
 681
 682 <p>Anyway, here is a nice tool for your tool box, might you never need
 683 it. :)</p>
 684 </div>
 685   <div class="tags">
 686
 687
 688
 689    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>.
 690
 691   </div>
 692  </div>
 693  <div class="padding"></div>
 694
 695  <div class="entry">
 696   <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>
 697   <div class="date">2010-08-07 14:45</div>
 698   <div class="body">
 699 <p>A few days ago, I
 700 <a href="http://people.skolelinux.org/pere/blog/Debian_Edu_roaming_workstation___at_the_university_of_Oslo.html">tried
 701 to install</a> a Roaming workation profile from Debian Edu/Squeeze
 702 while on the university network here at the University of Oslo, and
 703 noticed how much had to change to get it operational using the
 704 university infrastructure.  It was fairly easy, but it occured to me
 705 that Debian Edu would improve a lot if I could get the client to
 706 connect without any changes at all, and thus let the client configure
 707 itself during installation and first boot to use the infrastructure
 708 around it.  Now I am a huge step further along that road.</p>
 709
 710 <p>With our current squeeze-test packages, I can select the roaming
 711 workstation profile and get a working laptop connecting to the
 712 university LDAP server for user and group and our active directory
 713 servers for Kerberos authentication.  All this without any
 714 configuration at all during installation.  My users home directory got
 715 a bookmark in the KDE menu to mount it via SMB, with the correct URL.
 716 In short, openldap and sssd is correctly configured.  In addition to
 717 this, the client look for http://wpad/wpad.dat to configure a web
 718 proxy, and when it fail to find it no proxy settings are stored in
 719 /etc/environment and /etc/apt/apt.conf.  Iceweasel and KDE is
 720 configured to look for the same wpad configuration and also do not use
 721 a proxy when at the university network.  If the machine is moved to a
 722 network with such wpad setup, it would automatically use it when DHCP
 723 gave it a IP address.</p>
 724
 725 <p>The LDAP server is located using DNS, by first looking for the DNS
 726 entry ldap.$domain.  If this do not exist, it look for the
 727 _ldap._tcp.$domain SRV records and use the first one as the LDAP
 728 server.  Next, it connects to the LDAP server and search all
 729 namingContexts entries for posixAccount or posixGroup objects, and
 730 pick the first one as the LDAP base.  For Kerberos, a similar
 731 algorithm is used to locate the LDAP server, and the realm is the
 732 uppercase version of $domain.</p>
 733
 734 <p>So, what is not working, you might ask.  SMB mounting my home
 735 directory do not work.  No idea why, but suspected the incorrect
 736 Kerberos settings in /etc/krb5.conf and /etc/samba/smb.conf might be
 737 the cause.  These are not properly configured during installation, and
 738 had to be hand-edited to get the correct Kerberos realm and server,
 739 but SMB mounting still do not work. :(</p>
 740
 741 <p>With this automatic configuration in place, I expect a Debian Edu
 742 roaming profile installation would be able to automatically detect and
 743 connect to any site using LDAP and Kerberos for NSS directory and PAM
 744 authentication.  It should also work out of the box in a Active
 745 Directory environment providing posixAccount and posixGroup objects
 746 with UID and GID values.</p>
 747
 748 <p>If you want to help out with implementing these things for Debian
 749 Edu, please contact us on debian-edu@lists.debian.org.</p>
 750 </div>
 751   <div class="tags">
 752
 753
 754
 755    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>.
 756
 757   </div>
 758  </div>
 759  <div class="padding"></div>
 760
 761  <div class="entry">
 762   <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>
 763   <div class="date">2010-08-03 23:30</div>
 764   <div class="body">
 765 <p>The new roaming workstation profile in Debian Edu/Squeeze is fairly
 766 similar to the laptop setup am I working on using Ubuntu for the
 767 University of Oslo, and just for the heck of it, I tested today how
 768 hard it would be to integrate that profile into the university
 769 infrastructure.  In this case, it is the university LDAP server,
 770 Active Directory Kerberos server and SMB mounting from the Netapp file
 771 servers.</p>
 772
 773 <p>I was pleasantly surprised that the only three files needed to be
 774 changed (/etc/sssd/sssd.conf, /etc/ldap.conf and
 775 /etc/mklocaluser.d/20-debian-edu-config) and one file had to be added
 776 (/usr/share/perl5/Debian/Edu_Local.pm), to get the client working.
 777 Most of the changes were to get the client to use the university LDAP
 778 for NSS and Kerberos server for PAM, but one was to change a hard
 779 coded DNS domain name in the mklocaluser hook from .intern to
 780 .uio.no.</p>
 781
 782 <p>This testing was so encouraging, that I went ahead and adjusted the
 783 Debian Edu scripts and setup in subversion to centralise the roaming
 784 workstation setup a bit more and avoid the hardcoded DNS domain name,
 785 so that when I test this tomorrow, I expect to get away with modifying
 786 only /etc/sssd/sssd.conf and /etc/ldap.conf to get it to use the
 787 university servers.</p>
 788
 789 <p>My goal is to get the clients to have no hardcoded settings and
 790 fetch all their initial setup during installation and first boot, to
 791 allow them to be inserted also into environments where the default
 792 setup in Debian Edu has been changed or as with the university, where
 793 the environment is different but provides the protocols Debian Edu
 794 uses.</p>
 795 </div>
 796   <div class="tags">
 797
 798
 799
 800    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>.
 801
 802   </div>
 803  </div>
 804  <div class="padding"></div>
 805
 806  <p style="text-align: right;"><a href="index.rss"><img src="http://people.skolelinux.org/pere/blog/xml.gif" alt="RSS feed" width="36" height="14"></a></p>
 807
 808 <div id="sidebar">
 809
 810
 811
 812
 813
 814 <h2>Archive</h2>
 815 <ul>
 816
 817 <li>2010
 818 <ul>
 819
 820 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/01/">January (2)</a></li>
 821
 822 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/02/">February (1)</a></li>
 823
 824 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/03/">March (3)</a></li>
 825
 826 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/04/">April (3)</a></li>
 827
 828 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/05/">May (9)</a></li>
 829
 830 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/06/">June (14)</a></li>
 831
 832 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/07/">July (12)</a></li>
 833
 834 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/08/">August (10)</a></li>
 835
 836 </ul></li>
 837
 838 <li>2009
 839 <ul>
 840
 841 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/01/">January (8)</a></li>
 842
 843 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/02/">February (8)</a></li>
 844
 845 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/03/">March (12)</a></li>
 846
 847 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/04/">April (10)</a></li>
 848
 849 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/05/">May (9)</a></li>
 850
 851 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/06/">June (3)</a></li>
 852
 853 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/07/">July (4)</a></li>
 854
 855 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/08/">August (3)</a></li>
 856
 857 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/09/">September (1)</a></li>
 858
 859 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/10/">October (2)</a></li>
 860
 861 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/11/">November (3)</a></li>
 862
 863 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/12/">December (3)</a></li>
 864
 865 </ul></li>
 866
 867 <li>2008
 868 <ul>
 869
 870 <li><a href="http://people.skolelinux.org/pere/blog/archive/2008/11/">November (5)</a></li>
 871
 872 <li><a href="http://people.skolelinux.org/pere/blog/archive/2008/12/">December (7)</a></li>
 873
 874 </ul></li>
 875
 876 </ul>
 877
 878
 879
 880 <h2>Tags</h2>
 881 <ul>
 882
 883  <li><a href="http://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer (11)</a></li>
 884
 885  <li><a href="http://people.skolelinux.org/pere/blog/tags/amiga">amiga (1)</a></li>
 886
 887  <li><a href="http://people.skolelinux.org/pere/blog/tags/aros">aros (1)</a></li>
 888
 889  <li><a href="http://people.skolelinux.org/pere/blog/tags/bootsystem">bootsystem (10)</a></li>
 890
 891  <li><a href="http://people.skolelinux.org/pere/blog/tags/debian">debian (35)</a></li>
 892
 893  <li><a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu (42)</a></li>
 894
 895  <li><a href="http://people.skolelinux.org/pere/blog/tags/english">english (57)</a></li>
 896
 897  <li><a href="http://people.skolelinux.org/pere/blog/tags/fiksgatami">fiksgatami (1)</a></li>
 898
 899  <li><a href="http://people.skolelinux.org/pere/blog/tags/fildeling">fildeling (8)</a></li>
 900
 901  <li><a href="http://people.skolelinux.org/pere/blog/tags/kart">kart (3)</a></li>
 902
 903  <li><a href="http://people.skolelinux.org/pere/blog/tags/ldap">ldap (8)</a></li>
 904
 905  <li><a href="http://people.skolelinux.org/pere/blog/tags/lenker">lenker (2)</a></li>
 906
 907  <li><a href="http://people.skolelinux.org/pere/blog/tags/ltsp">ltsp (1)</a></li>
 908
 909  <li><a href="http://people.skolelinux.org/pere/blog/tags/multimedia">multimedia (5)</a></li>
 910
 911  <li><a href="http://people.skolelinux.org/pere/blog/tags/norsk">norsk (75)</a></li>
 912
 913  <li><a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug (97)</a></li>
 914
 915  <li><a href="http://people.skolelinux.org/pere/blog/tags/opphavsrett">opphavsrett (14)</a></li>
 916
 917  <li><a href="http://people.skolelinux.org/pere/blog/tags/personvern">personvern (15)</a></li>
 918
 919  <li><a href="http://people.skolelinux.org/pere/blog/tags/reprap">reprap (10)</a></li>
 920
 921  <li><a href="http://people.skolelinux.org/pere/blog/tags/robot">robot (2)</a></li>
 922
 923  <li><a href="http://people.skolelinux.org/pere/blog/tags/rss">rss (1)</a></li>
 924
 925  <li><a href="http://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet (12)</a></li>
 926
 927  <li><a href="http://people.skolelinux.org/pere/blog/tags/sitesummary">sitesummary (3)</a></li>
 928
 929  <li><a href="http://people.skolelinux.org/pere/blog/tags/standard">standard (13)</a></li>
 930
 931  <li><a href="http://people.skolelinux.org/pere/blog/tags/stavekontroll">stavekontroll (1)</a></li>
 932
 933  <li><a href="http://people.skolelinux.org/pere/blog/tags/video">video (10)</a></li>
 934
 935  <li><a href="http://people.skolelinux.org/pere/blog/tags/vitenskap">vitenskap (1)</a></li>
 936
 937  <li><a href="http://people.skolelinux.org/pere/blog/tags/web">web (7)</a></li>
 938
 939 </ul>
 940
 941 </div>
 942
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