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  13  <h1>
  14      <a href="https://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="https://people.skolelinux.org/pere/blog/rtlsdr_scanner__software_defined_radio_frequency_scanner_for_Linux____nice_free_software.html">rtlsdr-scanner, software defined radio frequency scanner for Linux  - nice free software</a></div>
  24       <div class="date"> 7th March 2023</div>
  25       <div class="body"><p>Today I finally found time to track down a useful radio frequency
  26 scanner for my software defined radio.  Just for fun I tried to locate
  27 the radios used in the areas, and a good start would be to scan all
  28 the frequencies to see what is in use.  I've tried to find a useful
  29 program earlier, but ran out of time before I managed to find a useful
  30 tool.  This time I was more successful, and after a few false leads I
  31 found a description of
  32 <a href="https://www.kali.org/tools/rtlsdr-scanner/">rtlsdr-scanner
  33 over at the Kali site</a>, and was able to track down
  34 <a href="https://gitlab.com/kalilinux/packages/rtlsdr-scanner.git">the
  35 Kali package git repository</a> to build a deb package for the
  36 scanner.  Sadly the package is missing from the Debian project itself,
  37 at least in Debian Bullseye.  Two runtime dependencies,
  38 <a href="https://gitlab.com/kalilinux/packages/python-visvis.git">python-visvis</a>
  39 and
  40 <a href="https://gitlab.com/kalilinux/packages/python-rtlsdr.git">python-rtlsdr</a>
  41 had to be built and installed separately.  Luckily '<tt>gbp
  42 buildpackage</tt>' handled them just fine and no further packages had
  43 to be manually built.  The end result worked out of the box after
  44 installation.</p>
  45
  46 <p>My initial scans for FM channels worked just fine, so I knew the
  47 scanner was functioning.  But when I tried to scan every frequency
  48 from 100 to 1000 MHz, the program stopped unexpectedly near the
  49 completion.  After some debugging I discovered USB software radio I
  50 used rejected frequencies above 948 MHz, triggering a unreported
  51 exception breaking the scan.  Changing the scan to end at 957 worked
  52 better.  I similarly found the lower limit to be around 15, and ended
  53 up with the following full scan:</p>
  54
  55 <p><a href="https://people.skolelinux.org/pere/blog/images/2023-04-07-radio-freq-scanning.png"><img src="https://people.skolelinux.org/pere/blog/images/2023-04-07-radio-freq-scanning.png" width="100%"></a></p>
  56
  57 <p>Saving the scan did not work, but exporting it as a CSV file worked
  58 just fine.  I ended up with around 477k CVS lines with dB level for
  59 the given frequency.</p>
  60
  61 <p>The save failure seem to be a missing UTF-8 encoding issue in the
  62 python code.  Will see if I can find time to send a patch
  63 <a href="https://github.com/CdeMills/RTLSDR-Scanner/">upstream</a>
  64 later to fix this exception:</p>
  65
  66 <pre>
  67 Traceback (most recent call last):
  68   File "/usr/lib/python3/dist-packages/rtlsdr_scanner/main_window.py", line 485, in __on_save
  69     save_plot(fullName, self.scanInfo, self.spectrum, self.locations)
  70   File "/usr/lib/python3/dist-packages/rtlsdr_scanner/file.py", line 408, in save_plot
  71     handle.write(json.dumps(data, indent=4))
  72 TypeError: a bytes-like object is required, not 'str'
  73 Traceback (most recent call last):
  74   File "/usr/lib/python3/dist-packages/rtlsdr_scanner/main_window.py", line 485, in __on_save
  75     save_plot(fullName, self.scanInfo, self.spectrum, self.locations)
  76   File "/usr/lib/python3/dist-packages/rtlsdr_scanner/file.py", line 408, in save_plot
  77     handle.write(json.dumps(data, indent=4))
  78 TypeError: a bytes-like object is required, not 'str'
  79 </pre>
  80
  81 <p>As usual, if you use Bitcoin and want to show your support of my
  82 activities, please send Bitcoin donations to my address
  83 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
  84 </div>
  85       <div class="tags">
  86
  87
  88         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/nice free software">nice free software</a>.
  89
  90
  91       </div>
  92     </div>
  93     <div class="padding"></div>
  94
  95     <div class="entry">
  96       <div class="title"><a href="https://people.skolelinux.org/pere/blog/OpenSnitch_available_in_Debian_Sid_and_Bookworm.html">OpenSnitch available in Debian Sid and Bookworm</a></div>
  97       <div class="date">25th February 2023</div>
  98       <div class="body"><p>Thanks to the efforts of the OpenSnitch lead developer Gustavo
  99 Iñiguez Goya allowing me to sponsor the upload,
 100 <a href="https://tracker.debian.org/pkg/opensnitch">the interactive
 101 application firewall OpenSnitch</a> is now available in Debian
 102 Testing, soon to become the next stable release of Debian.</p>
 103
 104 <p>This is a package which set up a network firewall on one or more
 105 machines, which is controlled by a graphical user interface that will
 106 ask the user if a program should be allowed to connect to the local
 107 network or the Internet.  If some background daemon is trying to dial
 108 home, it can be blocked from doing so with a simple mouse click, or by
 109 default simply by not doing anything when the GUI question dialog pop
 110 up.  A list of all programs discovered using the network is provided
 111 in the GUI, giving the user an overview of how the machine(s) programs
 112 use the network.</p>
 113
 114 <p>OpenSnitch was uploaded for NEW processing about a month ago, and I
 115 had little hope of it getting accepted and shaping up in time for the
 116 package freeze, but the Debian ftpmasters proved to be amazingly quick
 117 at checking out the package and it was accepted into the archive about
 118 week after the first upload.  It is now team maintained under the Go
 119 language team umbrella.  A few fixes to the default setup is only in
 120 Sid, and should migrate to Testing/Bookworm in a week.</p>
 121
 122 <p>During testing I ran into an
 123 <a href="https://github.com/evilsocket/opensnitch/issues/813">issue
 124 with Minecraft server broadcasts disappearing</a>, which was quickly
 125 resolved by the developer with a patch and a proposed configuration
 126 change.  I've been told this was caused by the Debian packages default
 127 use if /proc/ information to track down kernel status, instead of the
 128 newer eBPF module that can be used.  The reason is simply that
 129 upstream and I have failed to find a way to build the eBPF modules for
 130 OpenSnitch without a complete configured Linux kernel source tree,
 131 which as far as we can tell is unavailable as a build dependency in
 132 Debian.  We tried unsuccessfully so far to use the kernel-headers
 133 package.  It would be great if someone could provide some clues how to
 134 build eBPF modules on build daemons in Debian, possibly without the full
 135 kernel source.</p>
 136
 137 <p>As usual, if you use Bitcoin and want to show your support of my
 138 activities, please send Bitcoin donations to my address
 139 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 140 </div>
 141       <div class="tags">
 142
 143
 144         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 145
 146
 147       </div>
 148     </div>
 149     <div class="padding"></div>
 150
 151     <div class="entry">
 152       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Is_the_desktop_recommending_your_program_for_opening_its_files_.html">Is the desktop recommending your program for opening its files?</a></div>
 153       <div class="date">29th January 2023</div>
 154       <div class="body"><p>Linux desktop systems
 155 <a href="https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html">have
 156 standardized</a> how programs present themselves to the desktop
 157 system.  If a package include a .desktop file in
 158 /usr/share/applications/, Gnome, KDE, LXDE, Xfce and the other desktop
 159 environments will pick up the file and use its content to generate the
 160 menu of available programs in the system.  A lesser known fact is that
 161 a package can also explain to the desktop system how to recognize the
 162 files created by the program in question, and use it to open these
 163 files on request, for example via a GUI file browser.</p>
 164
 165 <p>A while back I ran into a package that did not tell the desktop
 166 system how to recognize its files and was not used to open its files
 167 in the file browser and fixed it.  In the process I wrote a simple
 168 debian/tests/ script to ensure the setup keep working.  It might be
 169 useful for other packages too, to ensure any future version of the
 170 package keep handling its own files.</p>
 171
 172 <p>For this to work the file format need a useful MIME type that can
 173 be used to identify the format.  If the file format do not yet have a
 174 MIME type, it should define one and preferably also
 175 <a href="https://www.iana.org/assignments/media-types/media-types.xhtml">register
 176 it with IANA</a> to ensure the MIME type string is reserved.</p>
 177
 178 <p>The script uses the <tt>xdg-mime</tt> program from xdg-utils to
 179 query the database of standardized package information and ensure it
 180 return sensible values.  It also need the location of an example file
 181 for xdg-mime to guess the format of.</p>
 182
 183 <pre>
 184 #!/bin/sh
 185 #
 186 # Author: Petter Reinholdtsen
 187 # License: GPL v2 or later at your choice.
 188 #
 189 # Validate the MIME setup, making sure motor types have
 190 # application/vnd.openmotor+yaml associated with them and is connected
 191 # to the openmotor desktop file.
 192
 193 retval=0
 194
 195 mimetype="application/vnd.openmotor+yaml"
 196 testfile="test/data/real/o3100/motor.ric"
 197 mydesktopfile="openmotor.desktop"
 198
 199 filemime="$(xdg-mime query filetype "$testfile")"
 200
 201 if [ "$mimetype" != "$filemime" ] ; then
 202     retval=1
 203     echo "error: xdg-mime claim motor file MIME type is $filemine, not $mimetype"
 204 else
 205     echo "success: xdg-mime report correct mime type $mimetype for motor file"
 206 fi
 207
 208 desktop=$(xdg-mime query default "$mimetype")
 209
 210 if [ "$mydesktopfile" != "$desktop" ]; then
 211     retval=1
 212     echo "error: xdg-mime claim motor file should be handled by $desktop, not $mydesktopfile"
 213 else
 214     echo "success: xdg-mime agree motor file should be handled by $mydesktopfile"
 215 fi
 216
 217 exit $retval
 218 </pre>
 219
 220 <p>It is a simple way to ensure your users are not very surprised when
 221 they try to open one of your file formats in their file browser.</p>
 222
 223 <p>As usual, if you use Bitcoin and want to show your support of my
 224 activities, please send Bitcoin donations to my address
 225 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 226 </div>
 227       <div class="tags">
 228
 229
 230         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 231
 232
 233       </div>
 234     </div>
 235     <div class="padding"></div>
 236
 237     <div class="entry">
 238       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Opensnitch__the_application_level_interactive_firewall__heading_into_the_Debian_archive.html">Opensnitch, the application level interactive firewall, heading into the Debian archive</a></div>
 239       <div class="date">22nd January 2023</div>
 240       <div class="body"><p>While reading a
 241 <a href="https://sneak.berlin/20230115/macos-scans-your-local-files-now/">blog
 242 post claiming MacOS X recently started scanning local files and
 243 reporting information about them to Apple</a>, even on a machine where
 244 all such callback features had been disabled, I came across a
 245 description of the Little Snitch application for MacOS X.  It seemed
 246 like a very nice tool to have in the tool box, and I decided to see if
 247 something similar was available for Linux.</p>
 248
 249 <p>It did not take long to find
 250 <a href="https://github.com/evilsocket/opensnitch">the OpenSnitch
 251 package</a>, which has been in development since 2017, and now is in
 252 version 1.5.0.  It has had a
 253 <a href="https://bugs.debian.org/909567">request for Debian
 254 packaging</a> since 2018, but no-one completed the job so far.  Just
 255 for fun, I decided to see if I could help, and I was very happy to
 256 discover that
 257 <a href="https://github.com/evilsocket/opensnitch/issues/304">upstream
 258 want a Debian package too</a>.</p>
 259
 260 <p>After struggling a bit with getting the program to run, figuring
 261 out building Go programs (and a little failed detour to look at eBPF
 262 builds too - help needed), I am very happy to report that I am
 263 sponsoring upstream to maintain the package in Debian, and it has
 264 since this morning been waiting in NEW for the ftpmasters to have a
 265 look.  Perhaps it can get into the archive in time for the Bookworm
 266 release?</p>
 267
 268 <p>As usual, if you use Bitcoin and want to show your support of my
 269 activities, please send Bitcoin donations to my address
 270 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 271 </div>
 272       <div class="tags">
 273
 274
 275         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 276
 277
 278       </div>
 279     </div>
 280     <div class="padding"></div>
 281
 282     <div class="entry">
 283       <div class="title"><a href="https://people.skolelinux.org/pere/blog/LinuxCNC_MQTT_publisher_component.html">LinuxCNC MQTT publisher component</a></div>
 284       <div class="date"> 8th January 2023</div>
 285       <div class="body"><p>I watched <a href="https://yewtu.be/watch?v=jmKUV3aNLjk">a 2015
 286 video from Andreas Schiffler</a> the other day, where he set up
 287 <a href="https://linuxcnc.org/">LinuxCNC</a> to send status
 288 information to the MQTT broker IBM Bluemix.  As I also use MQTT for
 289 graphing, it occured to me that a generic MQTT LinuxCNC component
 290 would be useful and I set out to implement it.  Today I got the first
 291 draft limping along and submitted as
 292 <a href="https://github.com/LinuxCNC/linuxcnc/pull/2253">a patch to the
 293 LinuxCNC project</a>.</p>
 294
 295 <p>The simple part was setting up the MQTT publishing code in Python.
 296 I already have set up other parts submitting data to my Mosquito MQTT
 297 broker, so I could reuse that code.  Writing a LinuxCNC component in
 298 Python as new to me, but using existing examples in the code
 299 repository and the extensive documentation, this was fairly straight
 300 forward.  The hardest part was creating a automated test for the
 301 component to ensure it was working.  Testing it in a simulated
 302 LinuxCNC machine proved very useful, as I discovered features I needed
 303 that I had not thought of yet, and adjusted the code quite a bit to
 304 make it easier to test without a operational MQTT broker
 305 available.</p>
 306
 307 <p>The draft is ready and working, but I am unsure which LinuxCNC HAL
 308 pins I should collect and publish by default (in other words, the
 309 default set of information pieces published), and how to get the
 310 machine name from the LinuxCNC INI file.  The latter is a minor
 311 detail, but I expect it would be useful in a setup with several
 312 machines available.  I am hoping for feedback from the experienced
 313 LinuxCNC developers and users, to make the component even better
 314 before it can go into the mainland LinuxCNC code base.</p>
 315
 316 <p>Since I started on the MQTT component, I came across
 317 <a href="https://yewtu.be/watch?v=Bqa2grG0XtA">another video from Kent
 318 VanderVelden</a> where he combine LinuxCNC with a set of screen glasses
 319 controlled by a Raspberry Pi, and it occured to me that it would
 320 be useful for such use cases if LinuxCNC also provided a REST API for
 321 querying its status.  I hope to start on such component once the MQTT
 322 component is working well.</p>
 323
 324 <p>As usual, if you use Bitcoin and want to show your support of my
 325 activities, please send Bitcoin donations to my address
 326 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 327 </div>
 328       <div class="tags">
 329
 330
 331         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc</a>, <a href="https://people.skolelinux.org/pere/blog/tags/robot">robot</a>.
 332
 333
 334       </div>
 335     </div>
 336     <div class="padding"></div>
 337
 338     <div class="entry">
 339       <div class="title"><a href="https://people.skolelinux.org/pere/blog/ONVIF_IP_camera_management_tool_finally_in_Debian.html">ONVIF IP camera management tool finally in Debian</a></div>
 340       <div class="date">24th December 2022</div>
 341       <div class="body"><p>Merry Christmas to you all.  Here is a small gift to all those with
 342 IP cameras following the <a href="https://www.onvif.org/">ONVIF
 343 specification</a>.  There is finally a nice command line and GUI tool
 344 in Debian to manage ONVIF IP cameras.  After working with upstream for
 345 a few months and sponsoring the upload, I am very happy to report that
 346 the <a href="https://tracker.debian.org/libonvif">libonvif package</a>
 347 entered Debian Sid last night.</p>
 348
 349 <p>The package provide a C library to communicate with such cameras, a
 350 command line tool to locate and update settings of (like password) the
 351 cameras and a GUI tool to configure and control the units as well as
 352 preview the video from the camera.  Libonvif is available on Both
 353 Linux and Windows and the GUI tool uses the Qt library.  The main
 354 competitors are non-free software, while libonvif is GNU GPL licensed.
 355 I am very glad Debian users in the future can control their cameras
 356 using a free software system provided by Debian.  But the ONVIF world
 357 is full of slightly broken firmware, where the cameras pretend to
 358 follow the ONVIF specification but fail to set some configuration
 359 values or refuse to provide video to more than one recipient at the
 360 time, and the onvif project is quite young and might take a while
 361 before it completely work with your camera.  Upstream seem eager to
 362 improve the library, so handling any broken camera might be just <a
 363 href="https://github.com/sr99622/libonvif/">a bug report away</a>.</p>
 364
 365 <p>The package just cleared NEW, and need a new source only upload
 366 before it can enter testing.  This will happen in the next few
 367 days.</p>
 368
 369 <p>As usual, if you use Bitcoin and want to show your support of my
 370 activities, please send Bitcoin donations to my address
 371 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 372 </div>
 373       <div class="tags">
 374
 375
 376         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia</a>, <a href="https://people.skolelinux.org/pere/blog/tags/standard">standard</a>, <a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance</a>.
 377
 378
 379       </div>
 380     </div>
 381     <div class="padding"></div>
 382
 383     <div class="entry">
 384       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Managing_and_using_ONVIF_IP_cameras_with_Linux.html">Managing and using ONVIF IP cameras with Linux</a></div>
 385       <div class="date">19th October 2022</div>
 386       <div class="body"><p>Recently I have been looking at how to control and collect data
 387 from a handful IP cameras using Linux.  I both wanted to change their
 388 settings and to make their imagery available via a free software
 389 service under my control.  Here is a summary of the tools I found.</p>
 390
 391 <p>First I had to identify the cameras and their protocols.  As far as
 392 I could tell, they were using some SOAP looking protocol and their
 393 internal web server seem to only work with Microsoft Internet Explorer
 394 with some proprietary binary plugin, which in these days of course is
 395 a security disaster and also made it impossible for me to use the
 396 camera web interface.  Luckily I discovered that the SOAP looking
 397 protocol is actually following <a href="https://www.onvif.org/">the
 398 ONVIF specification</a>, which seem to be supported by a lot of IP
 399 cameras these days.</p>
 400
 401 <p>Once the protocol was identified, I was able to find what appear to
 402 be the most popular way to configure ONVIF cameras, the free software
 403 Windows tool named
 404 <a href="https://sourceforge.net/projects/onvifdm/">ONVIF Device
 405 Manager</a>.  Lacking any other options at the time, I tried
 406 unsuccessfully to get it running using Wine, but was missing a dotnet
 407 40 library and I found no way around it to run it on Linux.</p>
 408
 409 <p>The next tool I found to configure the cameras were a non-free Linux Qt
 410 client <a href="https://www.lingodigit.com/onvif_nvcdemo.html">ONVIF
 411 Device Tool</a>.  I did not like its terms of use, so did not spend
 412 much time on it.</p>
 413
 414 <p>To collect the video and make it available in a web interface, I
 415 found the Zoneminder tool in Debian.  A recent version was able to
 416 automatically detect and configure ONVIF devices, so I could use it to
 417 set up motion detection in and collection of the camera output.  I had
 418 initial problems getting the ONVIF autodetection to work, as both
 419 Firefox and Chromium <a href="https://bugs.debian.org/1001188">refused
 420 the inter-tab communication</a> being used by the Zoneminder web
 421 pages, but managed to get konqueror to work.  Apparently the "Enhanced
 422 Tracking Protection" in Firefox cause the problem.  I ended up
 423 upgrading to the Bookworm edition of Zoneminder in the process to try
 424 to fix the issue, and believe the problem might be solved now.</p>
 425
 426 <p>In the process I came across the nice Linux GUI tool
 427 <a href="https://gitlab.com/caspermeijn/onvifviewer/">ONVIF Viewer</a>
 428 allowing me to preview the camera output and validate the login
 429 passwords required.  Sadly its author has grown tired of maintaining
 430 the software, so it might not see any future updates.  Which is sad,
 431 as the viewer is sightly unstable and the picture tend to lock up.
 432 Note, this lockup might be due to limitations in the cameras and not
 433 the viewer implementation.  I suspect the camera is only able to
 434 provide pictures to one client at the time, and the Zoneminder feed
 435 might interfere with the GUI viewer.  I have
 436 <a href="https://bugs.debian.org/1000820">asked for the tool to be
 437 included in Debian</a>.</p>
 438
 439 <p>Finally, I found what appear to be very nice Linux free software
 440 replacement for the Windows tool, named
 441 <a href="https://github.com/sr99622/libonvif/">libonvif</a>.  It
 442 provide a C library to talk to ONVIF devices as well as a command line
 443 and GUI tool using the library.  Using the GUI tool I was able to change
 444 the admin passwords and update other settings of the cameras.  I have
 445 <a href="https://bugs.debian.org/1021980">asked for the package to be
 446 included in Debian</a>.</p>
 447
 448 <p>As usual, if you use Bitcoin and want to show your support of my
 449 activities, please send Bitcoin donations to my address
 450 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 451
 452 <p><strong>Update 2022-10-20</strong>: Since my initial publication of
 453 this text, I got several suggestions for more free software Linux
 454 tools.  There is <a href="https://github.com/quatanium/python-onvif">a
 455 ONVIF python library</a> (already
 456 <a href="https://bugs.debian.org/824240">requested into Debian</a>) and
 457 <a href="https://github.com/FalkTannhaeuser/python-onvif-zeep">a python 3
 458 fork</a> using a different SOAP dependency.  There is also
 459 <a href="https://www.home-assistant.io/integrations/onvif/">support for
 460 ONVIF in Home Assistant</a>, and there is an alternative to Zoneminder
 461 called <a href="https://www.shinobi.video/">Shinobi</a>.  The latter
 462 two are not included in Debian either.  I have not tested any of these
 463 so far.</p>
 464 </div>
 465       <div class="tags">
 466
 467
 468         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia</a>, <a href="https://people.skolelinux.org/pere/blog/tags/standard">standard</a>, <a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance</a>.
 469
 470
 471       </div>
 472     </div>
 473     <div class="padding"></div>
 474
 475     <div class="entry">
 476       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Time_to_translate_the_Bullseye_edition_of_the_Debian_Administrator_s_Handbook.html">Time to translate the Bullseye edition of the Debian Administrator's Handbook</a></div>
 477       <div class="date">12th September 2022</div>
 478       <div class="body"><p align="center"><img align="center" src="http://people.skolelinux.org/pere/blog/images/2020-10-20-debian-handbook-nb-testprint.jpeg" width="60%"/></p>
 479
 480 <p>(The picture is of the previous edition.)</p>
 481
 482 <p>Almost two years after the previous Norwegian Bokmål translation of
 483 the "<a href="https://debian-handbook.info/">The Debian Administrator's
 484 Handbook</a>" was published, a new edition is finally being prepared.  The
 485 english text is updated, and it is time to start working on the
 486 translations.  Around 37 percent of the strings have been updated, one
 487 way or another, and the translations starting from a complete Debian Buster
 488 edition now need to bring their translation up from 63% to 100%.  The
 489 complete book is licensed using a Creative Commons license, and has
 490 been published in several languages over the years.  The translations
 491 are done by volunteers to bring Linux in their native tongue.  The
 492 last time I checked, it complete text was available in English,
 493 Norwegian Bokmål, German, Indonesian, Brazil Portuguese and Spanish.
 494 In addition, work has been started for Arabic (Morocco), Catalan,
 495 Chinese (Simplified), Chinese (Traditional), Croatian, Czech, Danish,
 496 Dutch, French, Greek, Italian, Japanese, Korean, Persian, Polish,
 497 Romanian, Russian, Swedish, Turkish and Vietnamese.</p>
 498
 499 <p>The translation is conducted on
 500 <a href="https://hosted.weblate.org/projects/debian-handbook/">the
 501 hosted weblate project page</a>.  Prospective translators are
 502 recommeded to subscribe to
 503 <a href="http://lists.alioth.debian.org/mailman/listinfo/debian-handbook-translators">the
 504 translators mailing list</a> and should also check out
 505 <a href="https://debian-handbook.info/contribute/">the instructions for
 506 contributors</a>.</p>
 507
 508 <p>I am one of the Norwegian Bokmål translators of this book, and we
 509 have just started.  Your contribution is most welcome.</p>
 510
 511 <p>As usual, if you use Bitcoin and want to show your support of my
 512 activities, please send Bitcoin donations to my address
 513 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 514 </div>
 515       <div class="tags">
 516
 517
 518         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/debian-handbook">debian-handbook</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 519
 520
 521       </div>
 522     </div>
 523     <div class="padding"></div>
 524
 525     <div class="entry">
 526       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Automatic_LinuxCNC_servo_PID_tuning_.html">Automatic LinuxCNC servo PID tuning?</a></div>
 527       <div class="date">16th July 2022</div>
 528       <div class="body"><p>While working on a CNC with servo motors controlled by the
 529 <a href="https://en.wikipedia.org/wiki/LinuxCNC">LinuxCNC</a>
 530 <a href="https://en.wikipedia.org/wiki/PID_controller">PID
 531 controller</a>, I recently had to learn how to tune the collection of values
 532 that control such mathematical machinery that a PID controller is.  It
 533 proved to be a lot harder than I hoped, and I still have not succeeded
 534 in getting the Z PID controller to successfully defy gravity, nor X
 535 and Y to move accurately and reliably.  But while climbing up this
 536 rather steep learning curve, I discovered that some motor control
 537 systems are able to tune their PID controllers.  I got the impression
 538 from the documentation that LinuxCNC were not.  This proved to be not
 539 true.</p>
 540
 541 <p>The LinuxCNC
 542 <a href="http://linuxcnc.org/docs/html/man/man9/pid.9.html">pid
 543 component</a> is the recommended PID controller to use.  It uses eight
 544 constants <tt>Pgain</tt>, <tt>Igain</tt>, <tt>Dgain</tt>,
 545 <tt>bias</tt>, <tt>FF0</tt>, <tt>FF1</tt>, <tt>FF2</tt> and
 546 <tt>FF3</tt> to calculate the output value based on current and wanted
 547 state, and all of these need to have a sensible value for the
 548 controller to behave properly.  Note, there are even more values
 549 involved, theser are just the most important ones.  In my case I need
 550 the X, Y and Z axes to follow the requested path with little error.
 551 This has proved quite a challenge for someone who have never tuned a
 552 PID controller before, but there is at least some help to be found.
 553
 554 <p>I discovered that included in LinuxCNC was this old PID component
 555 at_pid claiming to have auto tuning capabilities.  Sadly it had been
 556 neglected since 2011, and could not be used as a plug in replacement
 557 for the default pid component.  One would have to rewriting the
 558 LinuxCNC HAL setup to test at_pid.  This was rather sad, when I wanted
 559 to quickly test auto tuning to see if it did a better job than me at
 560 figuring out good P, I and D values to use.</p>
 561
 562 <p>I decided to have a look if the situation could be improved.  This
 563 involved trying to understand the code and history of the pid and
 564 at_pid components.  Apparently they had a common ancestor, as code
 565 structure, comments and variable names were quite close to each other.
 566 Sadly this was not reflected in the git history, making it hard to
 567 figure out what really happened.  My guess is that the author of
 568 <a href="https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/components/at_pid.c">at_pid.c</a>
 569 took a version of
 570 <a href="https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/components/pid.c">pid.c</a>,
 571 rewrote it to follow the structure he wished pid.c to have, then added
 572 support for auto tuning and finally got it included into the LinuxCNC
 573 repository.  The restructuring and lack of early history made it
 574 harder to figure out which part of the code were relevant to the auto
 575 tuning, and which part of the code needed to be updated to work the
 576 same way as the current pid.c implementation.  I started by trying to
 577 isolate relevant changes in pid.c, and applying them to at_pid.c.  My
 578 aim was to make sure the at_pid component could replace the pid
 579 component with a simple change in the HAL setup loadrt line, without
 580 having to "rewire" the rest of the HAL configuration.  After a few
 581 hours following this approach, I had learned quite a lot about the
 582 code structure of both components, while concluding I was heading down
 583 the wrong rabbit hole, and should get back to the surface and find a
 584 different path.</p>
 585
 586 <p>For the second attempt, I decided to throw away all the PID control
 587 related part of the original at_pid.c, and instead isolate and lift
 588 the auto tuning part of the code and inject it into a copy of pid.c.
 589 This ensured compatibility with the current pid component, while
 590 adding auto tuning as a run time option.  To make it easier to identify
 591 the relevant parts in the future, I wrapped all the auto tuning code
 592 with '#ifdef AUTO_TUNER'.  The end result behave just like the current
 593 pid component by default, as that part of the code is identical.  The
 594 <a href="https://github.com/LinuxCNC/linuxcnc/pull/1820">end result
 595 entered the LinuxCNC master branch</a> a few days ago.</p>
 596
 597 <p>To enable auto tuning, one need to set a few HAL pins in the PID
 598 component.  The most important ones are <tt>tune-effort</tt>,
 599 <tt>tune-mode</tt> and <tt>tune-start</tt>.  But lets take a step
 600 back, and see what the auto tuning code will do.  I do not know the
 601 mathematical foundation of the at_pid algorithm, but from observation
 602 I can tell that the algorithm will, when enabled, produce a square
 603 wave pattern centered around the <tt>bias</tt> value on the output pin
 604 of the PID controller.  This can be seen using the HAL Scope provided
 605 by LinuxCNC.  In my case, this is translated into voltage (+-10V) sent
 606 to the motor controller, which in turn is translated into motor speed.
 607 So at_pid will ask the motor to move the axis back and forth.  The
 608 number of cycles in the pattern is controlled by the
 609 <tt>tune-cycles</tt> pin, and the extremes of the wave pattern is
 610 controlled by the <tt>tune-effort</tt> pin.  Of course, trying to
 611 change the direction of a physical object instantly (as in going
 612 directly from a positive voltage to the equivalent negative voltage)
 613 do not change velocity instantly, and it take some time for the object
 614 to slow down and move in the opposite direction.  This result in a
 615 more smooth movement wave form, as the axis in question were vibrating
 616 back and forth.  When the axis reached the target speed in the
 617 opposing direction, the auto tuner change direction again.  After
 618 several of these changes, the average time delay between the 'peaks'
 619 and 'valleys' of this movement graph is then used to calculate
 620 proposed values for Pgain, Igain and Dgain, and insert them into the
 621 HAL model to use by the pid controller.  The auto tuned settings are
 622 not great, but htye work a lot better than the values I had been able
 623 to cook up on my own, at least for the horizontal X and Y axis.  But I
 624 had to use very small <tt>tune-effort<tt> values, as my motor
 625 controllers error out if the voltage change too quickly.  I've been
 626 less lucky with the Z axis, which is moving a heavy object up and
 627 down, and seem to confuse the algorithm.  The Z axis movement became a
 628 lot better when I introduced a <tt>bias</tt> value to counter the
 629 gravitational drag, but I will have to work a lot more on the Z axis
 630 PID values.</p>
 631
 632 <p>Armed with this knowledge, it is time to look at how to do the
 633 tuning.  Lets say the HAL configuration in question load the PID
 634 component for X, Y and Z like this:</p>
 635
 636 <blockquote><pre>
 637 loadrt pid names=pid.x,pid.y,pid.z
 638 </pre></blockquote>
 639
 640 <p>Armed with the new and improved at_pid component, the new line will
 641 look like this:</p>
 642
 643 <blockquote><pre>
 644 loadrt at_pid names=pid.x,pid.y,pid.z
 645 </pre></blockquote>
 646
 647 <p>The rest of the HAL setup can stay the same.  This work because the
 648 components are referenced by name.  If the component had used count=3
 649 instead, all use of pid.# had to be changed to at_pid.#.</p>
 650
 651 <p>To start tuning the X axis, move the axis to the middle of its
 652 range, to make sure it do not hit anything when it start moving back
 653 and forth.  Next, set the <tt>tune-effort</tt> to a low number in the
 654 output range.  I used 0.1 as my initial value.  Next, assign 1 to the
 655 <tt>tune-mode</tt> value. Note, this will disable the pid controlling
 656 part and feed 0 to the output pin, which in my case initially caused a
 657 lot of drift.  In my case it proved to be a good idea with X and Y to
 658 tune the motor driver to make sure 0 voltage stopped the motor
 659 rotation.  On the other hand, for the Z axis this proved to be a bad
 660 idea, so it will depend on your setup.  It might help to set the
 661 <tt>bias</tt> value to a output value that reduce or eliminate the
 662 axis drift.  Finally, after setting <tt>tune-mode</tt>, set
 663 <tt>tune-start</tt> to 1 to activate the auto tuning.  If all go well,
 664 your axis will vibrate for a few seconds and when it is done, new
 665 values for Pgain, Igain and Dgain will be active.  To test them,
 666 change <tt>tune-mode</tt> back to 0.  Note that this might cause the
 667 machine to suddenly jerk as it bring the axis back to its commanded
 668 position, which it might have drifted away from during tuning.  To
 669 summarize with some halcmd lines:</p>
 670
 671 <blockquote><pre>
 672 setp pid.x.tune-effort 0.1
 673 setp pid.x.tune-mode 1
 674 setp pid.x.tune-start 1
 675 # wait for the tuning to complete
 676 setp pid.x.tune-mode 0
 677 </pre></blockquote>
 678
 679 <p>After doing this task quite a few times while trying to figure out
 680 how to properly tune the PID controllers on the machine in, I decided
 681 to figure out if this process could be automated, and wrote a script
 682 to do the entire tuning process from power on.  The end result will
 683 ensure the machine is powered on and ready to run, home all axis if it
 684 is not already done, check that the extra tuning pins are available,
 685 move the axis to its mid point, run the auto tuning and re-enable the
 686 pid controller when it is done.  It can be run several times.  Check
 687 out the
 688 <a href="https://github.com/SebKuzminsky/MazakVQC1540/blob/bon-dev/scripts/run-auto-pid-tuner">run-auto-pid-tuner</a>
 689 script on github if you want to learn how it is done.</p>
 690
 691 <p>My hope is that this little adventure can inspire someone who know
 692 more about motor PID controller tuning can implement even better
 693 algorithms for automatic PID tuning in LinuxCNC, making life easier
 694 for both me and all the others that want to use LinuxCNC but lack the
 695 in depth knowledge needed to tune PID controllers well.</p>
 696
 697 <p>As usual, if you use Bitcoin and want to show your support of my
 698 activities, please send Bitcoin donations to my address
 699 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 700 </div>
 701       <div class="tags">
 702
 703
 704         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer</a>, <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc</a>, <a href="https://people.skolelinux.org/pere/blog/tags/robot">robot</a>.
 705
 706
 707       </div>
 708     </div>
 709     <div class="padding"></div>
 710
 711     <div class="entry">
 712       <div class="title"><a href="https://people.skolelinux.org/pere/blog/My_free_software_activity_of_late__2022_.html">My free software activity of late (2022)</a></div>
 713       <div class="date">20th June 2022</div>
 714       <div class="body"><p>I guess it is time to bring some light on the various free software
 715 and open culture activities and projects I have worked on or been
 716 involved in the last year and a half.</p>
 717
 718 <p>First, lets mention the book
 719 <a href="http://www.hungry.com/~pere/publisher/">releases I managed to
 720 publish</a>.  The Cory Doctorow book "Hvordan knuse
 721 overvåkningskapitalismen" argue that it is not the magic machine
 722 learning of the big technology companies that causes the surveillance
 723 capitalism to thrive, it is the lack of trust busting to enforce
 724 existing anti-monopoly laws.  I also published a family of
 725 dictionaries for machinists, one sorted on the English words, one
 726 sorted on the Norwegian and the last sorted on the North Sámi words.
 727 A bit on the back burner but not forgotten is the Debian
 728 Administrators Handbook, where a new edition is being worked on.  I
 729 have not spent as much time as I want to help bring it to completion,
 730 but hope I will get more spare time to look at it before the end of
 731 the year.</p>
 732
 733 <p>With my Debian had I have spent time on several projects, both
 734 updating existing packages, helping to bring in new packages and
 735 working with upstream projects to try to get them ready to go into
 736 Debian.  The list is rather long, and I will only mention my own
 737 isenkram, openmotor, vlc bittorrent plugin, xprintidle, norwegian
 738 letter style for latex, bs1770gain, and recordmydesktop.  In addition
 739 to these I have sponsored several packages into Debian, like audmes.</p>
 740
 741 <p>The last year I have looked at several infrastructure projects for
 742 collecting meter data and video surveillance recordings.  This include
 743 several ONVIF related tools like onvifviewer and zoneminder as well as
 744 rtl-433, wmbusmeters and rtl-wmbus.</p>
 745
 746 <p>In parallel with this I have looked at fabrication related free
 747 software solutions like pycam and LinuxCNC.  The latter recently
 748 gained improved translation support using po4a and weblate, which was
 749 a harder nut to crack that I had anticipated when I started.</p>
 750
 751 <p>Several hours have been spent translating free software to
 752 Norwegian Bokmål on the Weblate hosted service.  Do not have a
 753 complete list, but you will find my contributions in at least gnucash,
 754 minetest and po4a.</p>
 755
 756 <p>I also spent quite some time on the Norwegian archiving specification
 757 Noark 5, and its companion project Nikita implementing the API
 758 specification for Noark 5.</p>
 759
 760 <p>Recently I have been looking into free software tools to do company
 761 accounting here in Norway., which present an interesting mix between
 762 law, rules, regulations, format specifications and API interfaces.</p>
 763
 764 <p>I guess I should also mention the Norwegian community driven
 765 government interfacing projects Mimes Brønn and Fiksgatami, which have
 766 ended up in a kind of limbo while the future of the projects is being
 767 worked out.</p>
 768
 769 <p>These are just a few of the projects I have been involved it, and
 770 would like to give more visibility.  I'll stop here to avoid delaying
 771 this post.</p>
 772
 773 <p>As usual, if you use Bitcoin and want to show your support of my
 774 activities, please send Bitcoin donations to my address
 775 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 776 </div>
 777       <div class="tags">
 778
 779
 780         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 781
 782
 783       </div>
 784     </div>
 785     <div class="padding"></div>
 786
 787     <p style="text-align: right;"><a href="index.rss"><img src="https://people.skolelinux.org/pere/blog/xml.gif" alt="RSS feed" width="36" height="14" /></a></p>
 788     <div id="sidebar">
 789
 790
 791
 792 <h2>Archive</h2>
 793 <ul>
 794
 795 <li>2023
 796 <ul>
 797
 798 <li><a href="https://people.skolelinux.org/pere/blog/archive/2023/01/">January (3)</a></li>
 799
 800 <li><a href="https://people.skolelinux.org/pere/blog/archive/2023/02/">February (1)</a></li>
 801
 802 <li><a href="https://people.skolelinux.org/pere/blog/archive/2023/03/">March (1)</a></li>
 803
 804 </ul></li>
 805
 806 <li>2022
 807 <ul>
 808
 809 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/02/">February (1)</a></li>
 810
 811 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/03/">March (3)</a></li>
 812
 813 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/04/">April (2)</a></li>
 814
 815 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/06/">June (2)</a></li>
 816
 817 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/07/">July (1)</a></li>
 818
 819 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/09/">September (1)</a></li>
 820
 821 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/10/">October (1)</a></li>
 822
 823 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/12/">December (1)</a></li>
 824
 825 </ul></li>
 826
 827 <li>2021
 828 <ul>
 829
 830 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/01/">January (2)</a></li>
 831
 832 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/02/">February (1)</a></li>
 833
 834 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/05/">May (1)</a></li>
 835
 836 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/06/">June (1)</a></li>
 837
 838 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/07/">July (3)</a></li>
 839
 840 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/08/">August (1)</a></li>
 841
 842 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/09/">September (1)</a></li>
 843
 844 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/10/">October (1)</a></li>
 845
 846 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/12/">December (1)</a></li>
 847
 848 </ul></li>
 849
 850 <li>2020
 851 <ul>
 852
 853 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/02/">February (2)</a></li>
 854
 855 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/03/">March (2)</a></li>
 856
 857 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/04/">April (2)</a></li>
 858
 859 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/05/">May (3)</a></li>
 860
 861 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/06/">June (2)</a></li>
 862
 863 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/07/">July (1)</a></li>
 864
 865 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/09/">September (1)</a></li>
 866
 867 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/10/">October (1)</a></li>
 868
 869 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/11/">November (1)</a></li>
 870
 871 </ul></li>
 872
 873 <li>2019
 874 <ul>
 875
 876 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/01/">January (4)</a></li>
 877
 878 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/02/">February (3)</a></li>
 879
 880 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/03/">March (3)</a></li>
 881
 882 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/05/">May (2)</a></li>
 883
 884 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/06/">June (5)</a></li>
 885
 886 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/07/">July (2)</a></li>
 887
 888 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/08/">August (1)</a></li>
 889
 890 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/09/">September (1)</a></li>
 891
 892 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/11/">November (1)</a></li>
 893
 894 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/12/">December (4)</a></li>
 895
 896 </ul></li>
 897
 898 <li>2018
 899 <ul>
 900
 901 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/01/">January (1)</a></li>
 902
 903 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/02/">February (5)</a></li>
 904
 905 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/03/">March (5)</a></li>
 906
 907 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/04/">April (3)</a></li>
 908
 909 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/06/">June (2)</a></li>
 910
 911 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/07/">July (5)</a></li>
 912
 913 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/08/">August (3)</a></li>
 914
 915 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/09/">September (3)</a></li>
 916
 917 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/10/">October (5)</a></li>
 918
 919 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/11/">November (2)</a></li>
 920
 921 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/12/">December (4)</a></li>
 922
 923 </ul></li>
 924
 925 <li>2017
 926 <ul>
 927
 928 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/01/">January (4)</a></li>
 929
 930 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/02/">February (3)</a></li>
 931
 932 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/03/">March (5)</a></li>
 933
 934 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/04/">April (2)</a></li>
 935
 936 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/06/">June (5)</a></li>
 937
 938 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/07/">July (1)</a></li>
 939
 940 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/08/">August (1)</a></li>
 941
 942 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/09/">September (3)</a></li>
 943
 944 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/10/">October (5)</a></li>
 945
 946 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/11/">November (3)</a></li>
 947
 948 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/12/">December (4)</a></li>
 949
 950 </ul></li>
 951
 952 <li>2016
 953 <ul>
 954
 955 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/01/">January (3)</a></li>
 956
 957 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/02/">February (2)</a></li>
 958
 959 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/03/">March (3)</a></li>
 960
 961 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/04/">April (8)</a></li>
 962
 963 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/05/">May (8)</a></li>
 964
 965 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/06/">June (2)</a></li>
 966
 967 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/07/">July (2)</a></li>
 968
 969 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/08/">August (5)</a></li>
 970
 971 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/09/">September (2)</a></li>
 972
 973 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/10/">October (3)</a></li>
 974
 975 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/11/">November (8)</a></li>
 976
 977 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/12/">December (5)</a></li>
 978
 979 </ul></li>
 980
 981 <li>2015
 982 <ul>
 983
 984 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/01/">January (7)</a></li>
 985
 986 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/02/">February (6)</a></li>
 987
 988 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/03/">March (1)</a></li>
 989
 990 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/04/">April (4)</a></li>
 991
 992 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/05/">May (3)</a></li>
 993
 994 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/06/">June (4)</a></li>
 995
 996 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/07/">July (6)</a></li>
 997
 998 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/08/">August (2)</a></li>
 999
1000 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/09/">September (2)</a></li>
1001
1002 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/10/">October (9)</a></li>
1003
1004 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/11/">November (6)</a></li>
1005
1006 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/12/">December (3)</a></li>
1007
1008 </ul></li>
1009
1010 <li>2014
1011 <ul>
1012
1013 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/01/">January (2)</a></li>
1014
1015 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/02/">February (3)</a></li>
1016
1017 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/03/">March (8)</a></li>
1018
1019 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/04/">April (7)</a></li>
1020
1021 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/05/">May (1)</a></li>
1022
1023 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/06/">June (2)</a></li>
1024
1025 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/07/">July (2)</a></li>
1026
1027 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/08/">August (2)</a></li>
1028
1029 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/09/">September (5)</a></li>
1030
1031 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/10/">October (6)</a></li>
1032
1033 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/11/">November (3)</a></li>
1034
1035 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/12/">December (5)</a></li>
1036
1037 </ul></li>
1038
1039 <li>2013
1040 <ul>
1041
1042 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/01/">January (11)</a></li>
1043
1044 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/02/">February (9)</a></li>
1045
1046 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/03/">March (9)</a></li>
1047
1048 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/04/">April (6)</a></li>
1049
1050 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/05/">May (9)</a></li>
1051
1052 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/06/">June (10)</a></li>
1053
1054 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/07/">July (7)</a></li>
1055
1056 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/08/">August (3)</a></li>
1057
1058 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/09/">September (5)</a></li>
1059
1060 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/10/">October (7)</a></li>
1061
1062 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/11/">November (9)</a></li>
1063
1064 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/12/">December (3)</a></li>
1065
1066 </ul></li>
1067
1068 <li>2012
1069 <ul>
1070
1071 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/01/">January (7)</a></li>
1072
1073 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/02/">February (10)</a></li>
1074
1075 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/03/">March (17)</a></li>
1076
1077 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/04/">April (12)</a></li>
1078
1079 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/05/">May (12)</a></li>
1080
1081 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/06/">June (20)</a></li>
1082
1083 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/07/">July (17)</a></li>
1084
1085 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/08/">August (6)</a></li>
1086
1087 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/09/">September (9)</a></li>
1088
1089 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/10/">October (17)</a></li>
1090
1091 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/11/">November (10)</a></li>
1092
1093 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/12/">December (7)</a></li>
1094
1095 </ul></li>
1096
1097 <li>2011
1098 <ul>
1099
1100 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/01/">January (16)</a></li>
1101
1102 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/02/">February (6)</a></li>
1103
1104 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/03/">March (6)</a></li>
1105
1106 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/04/">April (7)</a></li>
1107
1108 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/05/">May (3)</a></li>
1109
1110 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/06/">June (2)</a></li>
1111
1112 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/07/">July (7)</a></li>
1113
1114 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/08/">August (6)</a></li>
1115
1116 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/09/">September (4)</a></li>
1117
1118 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/10/">October (2)</a></li>
1119
1120 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/11/">November (3)</a></li>
1121
1122 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/12/">December (1)</a></li>
1123
1124 </ul></li>
1125
1126 <li>2010
1127 <ul>
1128
1129 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/01/">January (2)</a></li>
1130
1131 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/02/">February (1)</a></li>
1132
1133 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/03/">March (3)</a></li>
1134
1135 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/04/">April (3)</a></li>
1136
1137 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/05/">May (9)</a></li>
1138
1139 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/06/">June (14)</a></li>
1140
1141 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/07/">July (12)</a></li>
1142
1143 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/08/">August (13)</a></li>
1144
1145 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/09/">September (7)</a></li>
1146
1147 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/10/">October (9)</a></li>
1148
1149 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/11/">November (13)</a></li>
1150
1151 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/12/">December (12)</a></li>
1152
1153 </ul></li>
1154
1155 <li>2009
1156 <ul>
1157
1158 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/01/">January (8)</a></li>
1159
1160 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/02/">February (8)</a></li>
1161
1162 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/03/">March (12)</a></li>
1163
1164 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/04/">April (10)</a></li>
1165
1166 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/05/">May (9)</a></li>
1167
1168 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/06/">June (3)</a></li>
1169
1170 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/07/">July (4)</a></li>
1171
1172 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/08/">August (3)</a></li>
1173
1174 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/09/">September (1)</a></li>
1175
1176 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/10/">October (2)</a></li>
1177
1178 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/11/">November (3)</a></li>
1179
1180 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/12/">December (3)</a></li>
1181
1182 </ul></li>
1183
1184 <li>2008
1185 <ul>
1186
1187 <li><a href="https://people.skolelinux.org/pere/blog/archive/2008/11/">November (5)</a></li>
1188
1189 <li><a href="https://people.skolelinux.org/pere/blog/archive/2008/12/">December (7)</a></li>
1190
1191 </ul></li>
1192
1193 </ul>
1194
1195
1196
1197 <h2>Tags</h2>
1198 <ul>
1199
1200  <li><a href="https://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer (19)</a></li>
1201
1202  <li><a href="https://people.skolelinux.org/pere/blog/tags/amiga">amiga (1)</a></li>
1203
1204  <li><a href="https://people.skolelinux.org/pere/blog/tags/aros">aros (1)</a></li>
1205
1206  <li><a href="https://people.skolelinux.org/pere/blog/tags/bankid">bankid (4)</a></li>
1207
1208  <li><a href="https://people.skolelinux.org/pere/blog/tags/betalkontant">betalkontant (9)</a></li>
1209
1210  <li><a href="https://people.skolelinux.org/pere/blog/tags/bitcoin">bitcoin (12)</a></li>
1211
1212  <li><a href="https://people.skolelinux.org/pere/blog/tags/bootsystem">bootsystem (17)</a></li>
1213
1214  <li><a href="https://people.skolelinux.org/pere/blog/tags/bsa">bsa (2)</a></li>
1215
1216  <li><a href="https://people.skolelinux.org/pere/blog/tags/chrpath">chrpath (2)</a></li>
1217
1218  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian">debian (189)</a></li>
1219
1220  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian edu">debian edu (159)</a></li>
1221
1222  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian-handbook">debian-handbook (9)</a></li>
1223
1224  <li><a href="https://people.skolelinux.org/pere/blog/tags/digistan">digistan (11)</a></li>
1225
1226  <li><a href="https://people.skolelinux.org/pere/blog/tags/dld">dld (18)</a></li>
1227
1228  <li><a href="https://people.skolelinux.org/pere/blog/tags/docbook">docbook (30)</a></li>
1229
1230  <li><a href="https://people.skolelinux.org/pere/blog/tags/drivstoffpriser">drivstoffpriser (4)</a></li>
1231
1232  <li><a href="https://people.skolelinux.org/pere/blog/tags/english">english (445)</a></li>
1233
1234  <li><a href="https://people.skolelinux.org/pere/blog/tags/fiksgatami">fiksgatami (23)</a></li>
1235
1236  <li><a href="https://people.skolelinux.org/pere/blog/tags/fildeling">fildeling (14)</a></li>
1237
1238  <li><a href="https://people.skolelinux.org/pere/blog/tags/freeculture">freeculture (34)</a></li>
1239
1240  <li><a href="https://people.skolelinux.org/pere/blog/tags/freedombox">freedombox (9)</a></li>
1241
1242  <li><a href="https://people.skolelinux.org/pere/blog/tags/frikanalen">frikanalen (20)</a></li>
1243
1244  <li><a href="https://people.skolelinux.org/pere/blog/tags/h264">h264 (20)</a></li>
1245
1246  <li><a href="https://people.skolelinux.org/pere/blog/tags/intervju">intervju (43)</a></li>
1247
1248  <li><a href="https://people.skolelinux.org/pere/blog/tags/isenkram">isenkram (16)</a></li>
1249
1250  <li><a href="https://people.skolelinux.org/pere/blog/tags/kart">kart (23)</a></li>
1251
1252  <li><a href="https://people.skolelinux.org/pere/blog/tags/kodi">kodi (4)</a></li>
1253
1254  <li><a href="https://people.skolelinux.org/pere/blog/tags/ldap">ldap (9)</a></li>
1255
1256  <li><a href="https://people.skolelinux.org/pere/blog/tags/lego">lego (5)</a></li>
1257
1258  <li><a href="https://people.skolelinux.org/pere/blog/tags/lenker">lenker (8)</a></li>
1259
1260  <li><a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc (4)</a></li>
1261
1262  <li><a href="https://people.skolelinux.org/pere/blog/tags/lsdvd">lsdvd (2)</a></li>
1263
1264  <li><a href="https://people.skolelinux.org/pere/blog/tags/ltsp">ltsp (1)</a></li>
1265
1266  <li><a href="https://people.skolelinux.org/pere/blog/tags/madewithcc">madewithcc (3)</a></li>
1267
1268  <li><a href="https://people.skolelinux.org/pere/blog/tags/mesh network">mesh network (8)</a></li>
1269
1270  <li><a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia (44)</a></li>
1271
1272  <li><a href="https://people.skolelinux.org/pere/blog/tags/nice free software">nice free software (14)</a></li>
1273
1274  <li><a href="https://people.skolelinux.org/pere/blog/tags/noark5">noark5 (23)</a></li>
1275
1276  <li><a href="https://people.skolelinux.org/pere/blog/tags/norsk">norsk (320)</a></li>
1277
1278  <li><a href="https://people.skolelinux.org/pere/blog/tags/nuug">nuug (198)</a></li>
1279
1280  <li><a href="https://people.skolelinux.org/pere/blog/tags/offentlig innsyn">offentlig innsyn (40)</a></li>
1281
1282  <li><a href="https://people.skolelinux.org/pere/blog/tags/open311">open311 (2)</a></li>
1283
1284  <li><a href="https://people.skolelinux.org/pere/blog/tags/opphavsrett">opphavsrett (75)</a></li>
1285
1286  <li><a href="https://people.skolelinux.org/pere/blog/tags/personvern">personvern (114)</a></li>
1287
1288  <li><a href="https://people.skolelinux.org/pere/blog/tags/raid">raid (2)</a></li>
1289
1290  <li><a href="https://people.skolelinux.org/pere/blog/tags/reactos">reactos (1)</a></li>
1291
1292  <li><a href="https://people.skolelinux.org/pere/blog/tags/reprap">reprap (11)</a></li>
1293
1294  <li><a href="https://people.skolelinux.org/pere/blog/tags/rfid">rfid (3)</a></li>
1295
1296  <li><a href="https://people.skolelinux.org/pere/blog/tags/robot">robot (17)</a></li>
1297
1298  <li><a href="https://people.skolelinux.org/pere/blog/tags/rss">rss (1)</a></li>
1299
1300  <li><a href="https://people.skolelinux.org/pere/blog/tags/ruter">ruter (7)</a></li>
1301
1302  <li><a href="https://people.skolelinux.org/pere/blog/tags/scraperwiki">scraperwiki (2)</a></li>
1303
1304  <li><a href="https://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet (59)</a></li>
1305
1306  <li><a href="https://people.skolelinux.org/pere/blog/tags/sitesummary">sitesummary (4)</a></li>
1307
1308  <li><a href="https://people.skolelinux.org/pere/blog/tags/skepsis">skepsis (5)</a></li>
1309
1310  <li><a href="https://people.skolelinux.org/pere/blog/tags/standard">standard (74)</a></li>
1311
1312  <li><a href="https://people.skolelinux.org/pere/blog/tags/stavekontroll">stavekontroll (7)</a></li>
1313
1314  <li><a href="https://people.skolelinux.org/pere/blog/tags/stortinget">stortinget (14)</a></li>
1315
1316  <li><a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance (64)</a></li>
1317
1318  <li><a href="https://people.skolelinux.org/pere/blog/tags/sysadmin">sysadmin (5)</a></li>
1319
1320  <li><a href="https://people.skolelinux.org/pere/blog/tags/usenix">usenix (2)</a></li>
1321
1322  <li><a href="https://people.skolelinux.org/pere/blog/tags/valg">valg (9)</a></li>
1323
1324  <li><a href="https://people.skolelinux.org/pere/blog/tags/verkidetfri">verkidetfri (20)</a></li>
1325
1326  <li><a href="https://people.skolelinux.org/pere/blog/tags/video">video (77)</a></li>
1327
1328  <li><a href="https://people.skolelinux.org/pere/blog/tags/vitenskap">vitenskap (4)</a></li>
1329
1330  <li><a href="https://people.skolelinux.org/pere/blog/tags/web">web (42)</a></li>
1331
1332 </ul>
1333
1334
1335     </div>
1336     <p style="text-align: right">
1337  Created by <a href="http://steve.org.uk/Software/chronicle">Chronicle v4.6</a>
1338 </p>
1339
1340   </body>
1341 </html>