X-Git-Url: http://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/eb2bfefa8ba4f868fc150d096326f1a2cf74be5e..2aafae50dc90da8ae2432aaeca9569fbe49cf7d7:/blog/index.rss diff --git a/blog/index.rss b/blog/index.rss index 99889b93e2..0581cf3d48 100644 --- a/blog/index.rss +++ b/blog/index.rss @@ -7,770 +7,712 @@ - Some notes on fault tolerant storage systems - http://people.skolelinux.org/pere/blog/Some_notes_on_fault_tolerant_storage_systems.html - http://people.skolelinux.org/pere/blog/Some_notes_on_fault_tolerant_storage_systems.html - Wed, 1 Nov 2017 15:35:00 +0100 - <p>If you care about how fault tolerant your storage is, you might -find these articles and papers interesting. They have formed how I -think of when designing a storage system.</p> - -<ul> - -<li>USENIX :login; <a -href="https://www.usenix.org/publications/login/summer2017/ganesan">Redundancy -Does Not Imply Fault Tolerance. Analysis of Distributed Storage -Reactions to Single Errors and Corruptions</a> by Aishwarya Ganesan, -Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, and Remzi -H. Arpaci-Dusseau</li> - -<li>ZDNet -<a href="http://www.zdnet.com/article/why-raid-5-stops-working-in-2009/">Why -RAID 5 stops working in 2009</a> by Robin Harris</li> - -<li>ZDNet -<a href="http://www.zdnet.com/article/why-raid-6-stops-working-in-2019/">Why -RAID 6 stops working in 2019</a> by Robin Harris</li> - -<li>USENIX FAST'07 -<a href="http://research.google.com/archive/disk_failures.pdf">Failure -Trends in a Large Disk Drive Population</a> by Eduardo Pinheiro, -Wolf-Dietrich Weber and Luiz André Barroso</li> - -<li>USENIX ;login: <a -href="https://www.usenix.org/system/files/login/articles/hughes12-04.pdf">Data -Integrity. Finding Truth in a World of Guesses and Lies</a> by Doug -Hughes</li> - -<li>USENIX FAST'08 -<a href="https://www.usenix.org/events/fast08/tech/full_papers/bairavasundaram/bairavasundaram_html/">An -cAnalysis of Data Corruption in the Storage Stack</a> - -L. N. Bairavasundaram, G. R. Goodson, B. Schroeder, A. C. -Arpaci-Dusseau, and R. H. Arpaci-Dusseau</li> - -<li>USENIX FAST'07 <a -href="https://www.usenix.org/legacy/events/fast07/tech/schroeder/schroeder_html/">Disk -failures in the real world: what does an MTTF of 1,000,000 hours mean -to you?</a> by B. Schroeder and G. A. Gibson.</li> - -<li>USENIX ;login: <a -href="https://www.usenix.org/events/fast08/tech/full_papers/jiang/jiang_html/">Are -Disks the Dominant Contributor for Storage Failures? A Comprehensive -Study of Storage Subsystem Failure Characteristics</a> by Weihang -Jiang, Chongfeng Hu, Yuanyuan Zhou, and Arkady Kanevsky</li> - -<li>SIGMETRICS 2007 -<a href="http://research.cs.wisc.edu/adsl/Publications/latent-sigmetrics07.pdf">An -analysis of latent sector errors in disk drives</a> - -L. N. Bairavasundaram, G. R. Goodson, S. Pasupathy, and J. Schindler</li> - -</ul> - -<p>Several of these research papers are based on data collected from -hundred thousands or millions of disk, and their findings are eye -opening. The short story is simply do not implicitly trust RAID or -redundant storage systems. Details matter. And unfortunately there -are few options on Linux addressing all the identified issues. Both -ZFS and Btrfs are doing a fairly good job, but have legal and -practical issues on their own. I wonder how cluster file systems like -Ceph do in this regard. After, all the old saying, you know you have -a distributed system when the crash of a compyter you have never heard -of stops you from getting any work done. The same holds true if fault -tolerance do not work.</p> - -<p>Just remember, in the end, it do not matter how redundant, or how -fault tolerant your storage is, if you do not continuously monitor its -status to detect and replace failed disks.</p> + Software created using taxpayers’ money should be Free Software + http://people.skolelinux.org/pere/blog/Software_created_using_taxpayers__money_should_be_Free_Software.html + http://people.skolelinux.org/pere/blog/Software_created_using_taxpayers__money_should_be_Free_Software.html + Thu, 30 Aug 2018 13:50:00 +0200 + <p>It might seem obvious that software created using tax money should +be available for everyone to use and improve. Free Software +Foundation Europe recentlystarted a campaign to help get more people +to understand this, and I just signed the petition on +<a href="https://publiccode.eu/">Public Money, Public Code</a> to help +them. I hope you too will do the same.</p> - Web services for writing academic LaTeX papers as a team - http://people.skolelinux.org/pere/blog/Web_services_for_writing_academic_LaTeX_papers_as_a_team.html - http://people.skolelinux.org/pere/blog/Web_services_for_writing_academic_LaTeX_papers_as_a_team.html - Tue, 31 Oct 2017 21:00:00 +0100 - <p>I was surprised today to learn that a friend in academia did not -know there are easily available web services available for writing -LaTeX documents as a team. I thought it was common knowledge, but to -make sure at least my readers are aware of it, I would like to mention -these useful services for writing LaTeX documents. Some of them even -provide a WYSIWYG editor to ease writing even further.</p> - -<p>There are two commercial services available, -<a href="https://sharelatex.com">ShareLaTeX</a> and -<a href="https://overleaf.com">Overleaf</a>. They are very easy to -use. Just start a new document, select which publisher to write for -(ie which LaTeX style to use), and start writing. Note, these two -have announced their intention to join forces, so soon it will only be -one joint service. I've used both for different documents, and they -work just fine. While -<a href="https://github.com/sharelatex/sharelatex">ShareLaTeX is free -software</a>, while the latter is not. According to <a -href="https://www.overleaf.com/help/17-is-overleaf-open-source">a -announcement from Overleaf</a>, they plan to keep the ShareLaTeX code -base maintained as free software.</p> - -But these two are not the only alternatives. -<a href="https://app.fiduswriter.org/">Fidus Writer</a> is another free -software solution with <a href="https://github.com/fiduswriter">the -source available on github</a>. I have not used it myself. Several -others can be found on the nice -<a href="https://alternativeto.net/software/sharelatex/">alterntiveTo -web service</a>. - -<p>If you like Google Docs or Etherpad, but would like to write -documents in LaTeX, you should check out these services. You can even -host your own, if you want to. :)</p> - + A bit more on privacy respecting health monitor / fitness tracker + http://people.skolelinux.org/pere/blog/A_bit_more_on_privacy_respecting_health_monitor___fitness_tracker.html + http://people.skolelinux.org/pere/blog/A_bit_more_on_privacy_respecting_health_monitor___fitness_tracker.html + Mon, 13 Aug 2018 09:00:00 +0200 + <p>A few days ago, I wondered if there are any privacy respecting +health monitors and/or fitness trackers available for sale these days. +I would like to buy one, but do not want to share my personal data +with strangers, nor be forced to have a mobile phone to get data out +of the unit. I've received some ideas, and would like to share them +with you. + +One interesting data point was a pointer to a Free Software app for +Android named +<a href="https://github.com/Freeyourgadget/Gadgetbridge/">Gadgetbridge</a>. +It provide cloudless collection and storing of data from a variety of +trackers. Its +<a href="https://github.com/Freeyourgadget/Gadgetbridge/#supported-devices">list +of supported devices</a> is a good indicator for units where the +protocol is fairly open, as it is obviously being handled by Free +Software. Other units are reportedly encrypting the collected +information with their own public key, making sure only the vendor +cloud service is able to extract data from the unit. The people +contacting me about Gadgetbirde said they were using +<a href="https://us.amazfit.com/shop/bip?variant=336750">Amazfit +Bip</a> and +<a href="http://www.xiaomimi6phone.com/xiaomi-mi-band-3-features-release-date-rumors/">Xiaomi +Band 3</a>.</p> + +<p>I also got a suggestion to look at some of the units from Garmin. +I was told their GPS watches can be connected via USB and show up as a +USB storage device with +<a href="https://www.gpsbabel.org/htmldoc-development/fmt_garmin_fit.html">Garmin +FIT files</a> containing the collected measurements. While +proprietary, FIT files apparently can be read at least by +<a href="https://www.gpsbabel.org">GPSBabel</a> and the +<a href="https://apps.nextcloud.com/apps/gpxpod">GpxPod</a> Nextcloud +app. It is unclear to me if they can read step count and heart rate +data. The person I talked to was using a +<a href="https://buy.garmin.com/en-US/US/p/564291">Garmin Forerunner +935</a>, which is a fairly expensive unit. I doubt it is worth it for +a unit where the vendor clearly is trying its best to move from open +to closed systems. I still remember when Garmin dropped NMEA support +in its GPSes.</p> + +<p>A final idea was to build ones own unit, perhaps by basing it on a +wearable hardware platforms like +<a href="https://learn.adafruit.com/flora-geo-watch">the Flora Geo +Watch</a>. Sound like fun, but I had more money than time to spend on +the topic, so I suspect it will have to wait for another time.</p> + +<p>While I was working on tracking down links, I came across an +inspiring TED talk by Dave Debronkart about +<a href="https://archive.org/details/DavedeBronkart_2010X">being a +e-patient</a>, and discovered the web site +<a href="https://participatorymedicine.org/epatients/">Participatory +Medicine</a>. If you too want to track your own health and fitness +without having information about your private life floating around on +computers owned by others, I recommend checking it out.</p> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p> - Locating IMDB IDs of movies in the Internet Archive using Wikidata - http://people.skolelinux.org/pere/blog/Locating_IMDB_IDs_of_movies_in_the_Internet_Archive_using_Wikidata.html - http://people.skolelinux.org/pere/blog/Locating_IMDB_IDs_of_movies_in_the_Internet_Archive_using_Wikidata.html - Wed, 25 Oct 2017 12:20:00 +0200 - <p>Recently, I needed to automatically check the copyright status of a -set of <a href="http://www.imdb.com/">The Internet Movie database -(IMDB)</a> entries, to figure out which one of the movies they refer -to can be freely distributed on the Internet. This proved to be -harder than it sounds. IMDB for sure list movies without any -copyright protection, where the copyright protection has expired or -where the movie is lisenced using a permissive license like one from -Creative Commons. These are mixed with copyright protected movies, -and there seem to be no way to separate these classes of movies using -the information in IMDB.</p> - -<p>First I tried to look up entries manually in IMDB, -<a href="https://www.wikipedia.org/">Wikipedia</a> and -<a href="https://www.archive.org/">The Internet Archive</a>, to get a -feel how to do this. It is hard to know for sure using these sources, -but it should be possible to be reasonable confident a movie is "out -of copyright" with a few hours work per movie. As I needed to check -almost 20,000 entries, this approach was not sustainable. I simply -can not work around the clock for about 6 years to check this data -set.</p> - -<p>I asked the people behind The Internet Archive if they could -introduce a new metadata field in their metadata XML for IMDB ID, but -was told that they leave it completely to the uploaders to update the -metadata. Some of the metadata entries had IMDB links in the -description, but I found no way to download all metadata files in bulk -to locate those ones and put that approach aside.</p> - -<p>In the process I noticed several Wikipedia articles about movies -had links to both IMDB and The Internet Archive, and it occured to me -that I could use the Wikipedia RDF data set to locate entries with -both, to at least get a lower bound on the number of movies on The -Internet Archive with a IMDB ID. This is useful based on the -assumption that movies distributed by The Internet Archive can be -legally distributed on the Internet. With some help from the RDF -community (thank you DanC), I was able to come up with this query to -pass to <a href="https://query.wikidata.org/">the SPARQL interface on -Wikidata</a>: - -<p><pre> -SELECT ?work ?imdb ?ia ?when ?label -WHERE -{ - ?work wdt:P31/wdt:P279* wd:Q11424. - ?work wdt:P345 ?imdb. - ?work wdt:P724 ?ia. - OPTIONAL { - ?work wdt:P577 ?when. - ?work rdfs:label ?label. - FILTER(LANG(?label) = "en"). - } -} -</pre></p> - -<p>If I understand the query right, for every film entry anywhere in -Wikpedia, it will return the IMDB ID and The Internet Archive ID, and -when the movie was released and its English title, if either or both -of the latter two are available. At the moment the result set contain -2338 entries. Of course, it depend on volunteers including both -correct IMDB and The Internet Archive IDs in the wikipedia articles -for the movie. It should be noted that the result will include -duplicates if the movie have entries in several languages. There are -some bogus entries, either because The Internet Archive ID contain a -typo or because the movie is not available from The Internet Archive. -I did not verify the IMDB IDs, as I am unsure how to do that -automatically.</p> - -<p>I wrote a small python script to extract the data set from Wikidata -and check if the XML metadata for the movie is available from The -Internet Archive, and after around 1.5 hour it produced a list of 2097 -free movies and their IMDB ID. In total, 171 entries in Wikidata lack -the refered Internet Archive entry. I assume the 70 "disappearing" -entries (ie 2338-2097-171) are duplicate entries.</p> - -<p>This is not too bad, given that The Internet Archive report to -contain <a href="https://archive.org/details/feature_films">5331 -feature films</a> at the moment, but it also mean more than 3000 -movies are missing on Wikipedia or are missing the pair of references -on Wikipedia.</p> - -<p>I was curious about the distribution by release year, and made a -little graph to show how the amount of free movies is spread over the -years:<p> - -<p><img src="http://people.skolelinux.org/pere/blog/images/2017-10-25-verk-i-det-fri-filmer.png"></p> - -<p>I expect the relative distribution of the remaining 3000 movies to -be similar.</p> - -<p>If you want to help, and want to ensure Wikipedia can be used to -cross reference The Internet Archive and The Internet Movie Database, -please make sure entries like this are listed under the "External -links" heading on the Wikipedia article for the movie:</p> - -<p><pre> -* {{Internet Archive film|id=FightingLady}} -* {{IMDb title|id=0036823|title=The Fighting Lady}} -</pre></p> - -<p>Please verify the links on the final page, to make sure you did not -introduce a typo.</p> - -<p>Here is the complete list, if you want to correct the 171 -identified Wikipedia entries with broken links to The Internet -Archive: <a href="http://www.wikidata.org/entity/Q1140317">Q1140317</a>, -<a href="http://www.wikidata.org/entity/Q458656">Q458656</a>, -<a href="http://www.wikidata.org/entity/Q458656">Q458656</a>, -<a href="http://www.wikidata.org/entity/Q470560">Q470560</a>, -<a href="http://www.wikidata.org/entity/Q743340">Q743340</a>, -<a href="http://www.wikidata.org/entity/Q822580">Q822580</a>, -<a href="http://www.wikidata.org/entity/Q480696">Q480696</a>, -<a href="http://www.wikidata.org/entity/Q128761">Q128761</a>, -<a href="http://www.wikidata.org/entity/Q1307059">Q1307059</a>, -<a href="http://www.wikidata.org/entity/Q1335091">Q1335091</a>, -<a 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href="http://www.wikidata.org/entity/Q3372642">Q3372642</a>, -<a href="http://www.wikidata.org/entity/Q3372816">Q3372816</a>, -<a href="http://www.wikidata.org/entity/Q3372909">Q3372909</a>, -<a href="http://www.wikidata.org/entity/Q7959649">Q7959649</a>, -<a href="http://www.wikidata.org/entity/Q7977485">Q7977485</a>, -<a href="http://www.wikidata.org/entity/Q7992684">Q7992684</a>, -<a href="http://www.wikidata.org/entity/Q3817966">Q3817966</a>, -<a href="http://www.wikidata.org/entity/Q3821852">Q3821852</a>, -<a href="http://www.wikidata.org/entity/Q3420907">Q3420907</a>, -<a href="http://www.wikidata.org/entity/Q3429733">Q3429733</a>, -<a href="http://www.wikidata.org/entity/Q774474">Q774474</a></p> + Privacy respecting health monitor / fitness tracker? + http://people.skolelinux.org/pere/blog/Privacy_respecting_health_monitor___fitness_tracker_.html + http://people.skolelinux.org/pere/blog/Privacy_respecting_health_monitor___fitness_tracker_.html + Tue, 7 Aug 2018 16:00:00 +0200 + <p>Dear lazyweb,</p> + +<p>I wonder, is there a fitness tracker / health monitor available for +sale today that respect the users privacy? With this I mean a +watch/bracelet capable of measuring pulse rate and other +fitness/health related values (and by all means, also the correct time +and location if possible), which is <strong>only</strong> provided for +me to extract/read from the unit with computer without a radio beacon +and Internet connection. In other words, it do not depend on a cell +phone app, and do make the measurements available via other peoples +computer (aka "the cloud"). The collected data should be available +using only free software. I'm not interested in depending on some +non-free software that will leave me high and dry some time in the +future. I've been unable to find any such unit. I would like to buy +it. The ones I have seen for sale here in Norway are proud to report +that they share my health data with strangers (aka "cloud enabled"). +Is there an alternative? I'm not interested in giving money to people +requiring me to accept "privacy terms" to allow myself to measure my +own health.</p> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p> - A one-way wall on the border? - http://people.skolelinux.org/pere/blog/A_one_way_wall_on_the_border_.html - http://people.skolelinux.org/pere/blog/A_one_way_wall_on_the_border_.html - Sat, 14 Oct 2017 22:10:00 +0200 - <p>I find it fascinating how many of the people being locked inside -the proposed border wall between USA and Mexico support the idea. The -proposal to keep Mexicans out reminds me of -<a href="http://www.history.com/news/10-things-you-may-not-know-about-the-berlin-wall">the -propaganda twist from the East Germany government</a> calling the wall -the “Antifascist Bulwark” after erecting the Berlin Wall, claiming -that the wall was erected to keep enemies from creeping into East -Germany, while it was obvious to the people locked inside it that it -was erected to keep the people from escaping.</p> - -<p>Do the people in USA supporting this wall really believe it is a -one way wall, only keeping people on the outside from getting in, -while not keeping people in the inside from getting out?</p> + Sharing images with friends and family using RSS and EXIF/XMP metadata + http://people.skolelinux.org/pere/blog/Sharing_images_with_friends_and_family_using_RSS_and_EXIF_XMP_metadata.html + http://people.skolelinux.org/pere/blog/Sharing_images_with_friends_and_family_using_RSS_and_EXIF_XMP_metadata.html + Tue, 31 Jul 2018 23:30:00 +0200 + <p>For a while now, I have looked for a sensible way to share images +with my family using a self hosted solution, as it is unacceptable to +place images from my personal life under the control of strangers +working for data hoarders like Google or Dropbox. The last few days I +have drafted an approach that might work out, and I would like to +share it with you. I would like to publish images on a server under +my control, and point some Internet connected display units using some +free and open standard to the images I published. As my primary +language is not limited to ASCII, I need to store metadata using +UTF-8. Many years ago, I hoped to find a digital photo frame capable +of reading a RSS feed with image references (aka using the +&lt;enclosure&gt; RSS tag), but was unable to find a current supplier +of such frames. In the end I gave up that approach.</p> + +<p>Some months ago, I discovered that +<a href="https://www.jwz.org/xscreensaver/">XScreensaver</a> is able to +read images from a RSS feed, and used it to set up a screen saver on +my home info screen, showing images from the Daily images feed from +NASA. This proved to work well. More recently I discovered that +<a href="https://kodi.tv">Kodi</a> (both using +<a href="https://www.openelec.tv/">OpenELEC</a> and +<a href="https://libreelec.tv">LibreELEC</a>) provide the +<a href="https://github.com/grinsted/script.screensaver.feedreader">Feedreader</a> +screen saver capable of reading a RSS feed with images and news. For +fun, I used it this summer to test Kodi on my parents TV by hooking up +a Raspberry PI unit with LibreELEC, and wanted to provide them with a +screen saver showing selected pictures from my selection.</p> + +<p>Armed with motivation and a test photo frame, I set out to generate +a RSS feed for the Kodi instance. I adjusted my <a +href="https://freedombox.org/">Freedombox</a> instance, created +/var/www/html/privatepictures/, wrote a small Perl script to extract +title and description metadata from the photo files and generate the +RSS file. I ended up using Perl instead of python, as the +libimage-exiftool-perl Debian package seemed to handle the EXIF/XMP +tags I ended up using, while python3-exif did not. The relevant EXIF +tags only support ASCII, so I had to find better alternatives. XMP +seem to have the support I need.</p> + +<p>I am a bit unsure which EXIF/XMP tags to use, as I would like to +use tags that can be easily added/updated using normal free software +photo managing software. I ended up using the tags set using this +exiftool command, as these tags can also be set using digiKam:</p> + +<blockquote><pre> +exiftool -headline='The RSS image title' \ + -description='The RSS image description.' \ + -subject+=for-family photo.jpeg +</pre></blockquote> + +<p>I initially tried the "-title" and "keyword" tags, but they were +invisible in digiKam, so I changed to "-headline" and "-subject". I +use the keyword/subject 'for-family' to flag that the photo should be +shared with my family. Images with this keyword set are located and +copied into my Freedombox for the RSS generating script to find.</p> + +<p>Are there better ways to do this? Get in touch if you have better +suggestions.</p> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p> - Generating 3D prints in Debian using Cura and Slic3r(-prusa) - http://people.skolelinux.org/pere/blog/Generating_3D_prints_in_Debian_using_Cura_and_Slic3r__prusa_.html - http://people.skolelinux.org/pere/blog/Generating_3D_prints_in_Debian_using_Cura_and_Slic3r__prusa_.html - Mon, 9 Oct 2017 10:50:00 +0200 - <p>At my nearby maker space, -<a href="http://sonen.ifi.uio.no/">Sonen</a>, I heard the story that it -was easier to generate gcode files for theyr 3D printers (Ultimake 2+) -on Windows and MacOS X than Linux, because the software involved had -to be manually compiled and set up on Linux while premade packages -worked out of the box on Windows and MacOS X. I found this annoying, -as the software involved, -<a href="https://github.com/Ultimaker/Cura">Cura</a>, is free software -and should be trivial to get up and running on Linux if someone took -the time to package it for the relevant distributions. I even found -<a href="https://bugs.debian.org/706656">a request for adding into -Debian</a> from 2013, which had seem some activity over the years but -never resulted in the software showing up in Debian. So a few days -ago I offered my help to try to improve the situation.</p> - -<p>Now I am very happy to see that all the packages required by a -working Cura in Debian are uploaded into Debian and waiting in the NEW -queue for the ftpmasters to have a look. You can track the progress -on -<a href="https://qa.debian.org/developer.php?email=3dprinter-general%40lists.alioth.debian.org">the -status page for the 3D printer team</a>.</p> - -<p>The uploaded packages are a bit behind upstream, and was uploaded -now to get slots in <a href="https://ftp-master.debian.org/new.html">the NEW -queue</a> while we work up updating the packages to the latest -upstream version.</p> - -<p>On a related note, two competitors for Cura, which I found harder -to use and was unable to configure correctly for Ultimaker 2+ in the -short time I spent on it, are already in Debian. If you are looking -for 3D printer "slicers" and want something already available in -Debian, check out -<a href="https://tracker.debian.org/pkg/slic3r">slic3r</a> and -<a href="https://tracker.debian.org/pkg/slic3r-prusa">slic3r-prusa</a>. -The latter is a fork of the former.</p> + Simple streaming the Linux desktop to Kodi using GStreamer and RTP + http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html + http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html + Thu, 12 Jul 2018 17:55:00 +0200 + <p>Last night, I wrote +<a href="http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html">a +recipe to stream a Linux desktop using VLC to a instance of Kodi</a>. +During the day I received valuable feedback, and thanks to the +suggestions I have been able to rewrite the recipe into a much simpler +approach requiring no setup at all. It is a single script that take +care of it all.</p> + +<p>This new script uses GStreamer instead of VLC to capture the +desktop and stream it to Kodi. This fixed the video quality issue I +saw initially. It further removes the need to add a m3u file on the +Kodi machine, as it instead connects to +<a href="https://kodi.wiki/view/JSON-RPC_API/v8">the JSON-RPC API in +Kodi</a> and simply ask Kodi to play from the stream created using +GStreamer. Streaming the desktop to Kodi now become trivial. Copy +the script below, run it with the DNS name or IP address of the kodi +server to stream to as the only argument, and watch your screen show +up on the Kodi screen. Note, it depend on multicast on the local +network, so if you need to stream outside the local network, the +script must be modified. Also note, I have no idea if audio work, as +I only care about the picture part.</p> + +<blockquote><pre> +#!/bin/sh +# +# Stream the Linux desktop view to Kodi. See +# http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html +# for backgorund information. + +# Make sure the stream is stopped in Kodi and the gstreamer process is +# killed if something go wrong (for example if curl is unable to find the +# kodi server). Do the same when interrupting this script. +kodicmd() { + host="$1" + cmd="$2" + params="$3" + curl --silent --header 'Content-Type: application/json' \ + --data-binary "{ \"id\": 1, \"jsonrpc\": \"2.0\", \"method\": \"$cmd\", \"params\": $params }" \ + "http://$host/jsonrpc" +} +cleanup() { + if [ -n "$kodihost" ] ; then + # Stop the playing when we end + playerid=$(kodicmd "$kodihost" Player.GetActivePlayers "{}" | + jq .result[].playerid) + kodicmd "$kodihost" Player.Stop "{ \"playerid\" : $playerid }" > /dev/null + fi + if [ "$gstpid" ] && kill -0 "$gstpid" >/dev/null 2>&1; then + kill "$gstpid" + fi +} +trap cleanup EXIT INT + +if [ -n "$1" ]; then + kodihost=$1 + shift +else + kodihost=kodi.local +fi + +mcast=239.255.0.1 +mcastport=1234 +mcastttl=1 + +pasrc=$(pactl list | grep -A2 'Source #' | grep 'Name: .*\.monitor$' | \ + cut -d" " -f2|head -1) +gst-launch-1.0 ximagesrc use-damage=0 ! video/x-raw,framerate=30/1 ! \ + videoconvert ! queue2 ! \ + x264enc bitrate=8000 speed-preset=superfast tune=zerolatency qp-min=30 \ + key-int-max=15 bframes=2 ! video/x-h264,profile=high ! queue2 ! \ + mpegtsmux alignment=7 name=mux ! rndbuffersize max=1316 min=1316 ! \ + udpsink host=$mcast port=$mcastport ttl-mc=$mcastttl auto-multicast=1 sync=0 \ + pulsesrc device=$pasrc ! audioconvert ! queue2 ! avenc_aac ! queue2 ! mux. \ + > /dev/null 2>&1 & +gstpid=$! + +# Give stream a second to get going +sleep 1 + +# Ask kodi to start streaming using its JSON-RPC API +kodicmd "$kodihost" Player.Open \ + "{\"item\": { \"file\": \"udp://@$mcast:$mcastport\" } }" > /dev/null + +# wait for gst to end +wait "$gstpid" +</pre></blockquote> + +<p>I hope you find the approach useful. I know I do.</p> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p> - Mangler du en skrue, eller har du en skrue løs? - http://people.skolelinux.org/pere/blog/Mangler_du_en_skrue__eller_har_du_en_skrue_l_s_.html - http://people.skolelinux.org/pere/blog/Mangler_du_en_skrue__eller_har_du_en_skrue_l_s_.html - Wed, 4 Oct 2017 09:40:00 +0200 - Når jeg holder på med ulike prosjekter, så trenger jeg stadig ulike -skruer. Det siste prosjektet jeg holder på med er å lage -<a href="https://www.thingiverse.com/thing:676916">en boks til en -HDMI-touch-skjerm</a> som skal brukes med Raspberry Pi. Boksen settes -sammen med skruer og bolter, og jeg har vært i tvil om hvor jeg kan -få tak i de riktige skruene. Clas Ohlson og Jernia i nærheten har -sjelden hatt det jeg trenger. Men her om dagen fikk jeg et fantastisk -tips for oss som bor i Oslo. -<a href="http://www.zachskruer.no/">Zachariassen Jernvare AS</a> i -<a href="http://www.openstreetmap.org/?mlat=59.93421&mlon=10.76795#map=19/59.93421/10.76795">Hegermannsgate -23A på Torshov</a> har et fantastisk utvalg, og åpent mellom 09:00 og -17:00. De selger skruer, muttere, bolter, skiver etc i løs vekt, og -så langt har jeg fått alt jeg har lett etter. De har i tillegg det -meste av annen jernvare, som verktøy, lamper, ledninger, etc. Jeg -håper de har nok kunder til å holde det gående lenge, da dette er en -butikk jeg kommer til å besøke ofte. Butikken er et funn å ha i -nabolaget for oss som liker å bygge litt selv. :)</p> + Streaming the Linux desktop to Kodi using VLC and RTSP + http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html + http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html + Thu, 12 Jul 2018 02:00:00 +0200 + <p>PS: See +<ahref="http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html">the +followup post</a> for a even better approach.</p> + +<p>A while back, I was asked by a friend how to stream the desktop to +my projector connected to Kodi. I sadly had to admit that I had no +idea, as it was a task I never had tried. Since then, I have been +looking for a way to do so, preferable without much extra software to +install on either side. Today I found a way that seem to kind of +work. Not great, but it is a start.</p> + +<p>I had a look at several approaches, for example +<a href="https://github.com/mfoetsch/dlna_live_streaming">using uPnP +DLNA as described in 2011</a>, but it required a uPnP server, fuse and +local storage enough to store the stream locally. This is not going +to work well for me, lacking enough free space, and it would +impossible for my friend to get working.</p> + +<p>Next, it occurred to me that perhaps I could use VLC to create a +video stream that Kodi could play. Preferably using +broadcast/multicast, to avoid having to change any setup on the Kodi +side when starting such stream. Unfortunately, the only recipe I +could find using multicast used the rtp protocol, and this protocol +seem to not be supported by Kodi.</p> + +<p>On the other hand, the rtsp protocol is working! Unfortunately I +have to specify the IP address of the streaming machine in both the +sending command and the file on the Kodi server. But it is showing my +desktop, and thus allow us to have a shared look on the big screen at +the programs I work on.</p> + +<p>I did not spend much time investigating codeces. I combined the +rtp and rtsp recipes from +<a href="https://wiki.videolan.org/Documentation:Streaming_HowTo/Command_Line_Examples/">the +VLC Streaming HowTo/Command Line Examples</a>, and was able to get +this working on the desktop/streaming end.</p> + +<blockquote><pre> +vlc screen:// --sout \ + '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{dst=projector.local,port=1234,sdp=rtsp://192.168.11.4:8080/test.sdp}' +</pre></blockquote> + +<p>I ssh-ed into my Kodi box and created a file like this with the +same IP address:</p> + +<blockquote><pre> +echo rtsp://192.168.11.4:8080/test.sdp \ + > /storage/videos/screenstream.m3u +</pre></blockquote> + +<p>Note the 192.168.11.4 IP address is my desktops IP address. As far +as I can tell the IP must be hardcoded for this to work. In other +words, if someone elses machine is going to do the steaming, you have +to update screenstream.m3u on the Kodi machine and adjust the vlc +recipe. To get started, locate the file in Kodi and select the m3u +file while the VLC stream is running. The desktop then show up in my +big screen. :)</p> + +<p>When using the same technique to stream a video file with audio, +the audio quality is really bad. No idea if the problem is package +loss or bad parameters for the transcode. I do not know VLC nor Kodi +enough to tell.</p> + +<p><strong>Update 2018-07-12</strong>: Johannes Schauer send me a few +succestions and reminded me about an important step. The "screen:" +input source is only available once the vlc-plugin-access-extra +package is installed on Debian. Without it, you will see this error +message: "VLC is unable to open the MRL 'screen://'. Check the log +for details." He further found that it is possible to drop some parts +of the VLC command line to reduce the amount of hardcoded information. +It is also useful to consider using cvlc to avoid having the VLC +window in the desktop view. In sum, this give us this command line on +the source end + +<blockquote><pre> +cvlc screen:// --sout \ + '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{sdp=rtsp://:8080/}' +</pre></blockquote> + +<p>and this on the Kodi end<p> + +<blockquote><pre> +echo rtsp://192.168.11.4:8080/ \ + > /storage/videos/screenstream.m3u +</pre></blockquote> + +<p>Still bad image quality, though. But I did discover that streaming +a DVD using dvdsimple:///dev/dvd as the source had excellent video and +audio quality, so I guess the issue is in the input or transcoding +parts, not the rtsp part. I've tried to change the vb and ab +parameters to use more bandwidth, but it did not make a +difference.</p> + +<p>I further received a suggestion from Einar Haraldseid to try using +gstreamer instead of VLC, and this proved to work great! He also +provided me with the trick to get Kodi to use a multicast stream as +its source. By using this monstrous oneliner, I can stream my desktop +with good video quality in reasonable framerate to the 239.255.0.1 +multicast address on port 1234: + +<blockquote><pre> +gst-launch-1.0 ximagesrc use-damage=0 ! video/x-raw,framerate=30/1 ! \ + videoconvert ! queue2 ! \ + x264enc bitrate=8000 speed-preset=superfast tune=zerolatency qp-min=30 \ + key-int-max=15 bframes=2 ! video/x-h264,profile=high ! queue2 ! \ + mpegtsmux alignment=7 name=mux ! rndbuffersize max=1316 min=1316 ! \ + udpsink host=239.255.0.1 port=1234 ttl-mc=1 auto-multicast=1 sync=0 \ + pulsesrc device=$(pactl list | grep -A2 'Source #' | \ + grep 'Name: .*\.monitor$' | cut -d" " -f2|head -1) ! \ + audioconvert ! queue2 ! avenc_aac ! queue2 ! mux. +</pre></blockquote> + +<p>and this on the Kodi end<p> + +<blockquote><pre> +echo udp://@239.255.0.1:1234 \ + > /storage/videos/screenstream.m3u +</pre></blockquote> + +<p>Note the trick to pick a valid pulseaudio source. It might not +pick the one you need. This approach will of course lead to trouble +if more than one source uses the same multicast port and address. +Note the ttl-mc=1 setting, which limit the multicast packages to the +local network. If the value is increased, your screen will be +broadcasted further, one network "hop" for each increase (read up on +multicast to learn more. :)!</p> + +<p>Having cracked how to get Kodi to receive multicast streams, I +could use this VLC command to stream to the same multicast address. +The image quality is way better than the rtsp approach, but gstreamer +seem to be doing a better job.</p> + +<blockquote><pre> +cvlc screen:// --sout '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{mux=ts,dst=239.255.0.1,port=1234,sdp=sap}' +</pre></blockquote> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p> - Visualizing GSM radio chatter using gr-gsm and Hopglass - http://people.skolelinux.org/pere/blog/Visualizing_GSM_radio_chatter_using_gr_gsm_and_Hopglass.html - http://people.skolelinux.org/pere/blog/Visualizing_GSM_radio_chatter_using_gr_gsm_and_Hopglass.html - Fri, 29 Sep 2017 10:30:00 +0200 - <p>Every mobile phone announce its existence over radio to the nearby -mobile cell towers. And this radio chatter is available for anyone -with a radio receiver capable of receiving them. Details about the -mobile phones with very good accuracy is of course collected by the -phone companies, but this is not the topic of this blog post. The -mobile phone radio chatter make it possible to figure out when a cell -phone is nearby, as it include the SIM card ID (IMSI). By paying -attention over time, one can see when a phone arrive and when it leave -an area. I believe it would be nice to make this information more -available to the general public, to make more people aware of how -their phones are announcing their whereabouts to anyone that care to -listen.</p> - -<p>I am very happy to report that we managed to get something -visualizing this information up and running for -<a href="http://norwaymakers.org/osf17">Oslo Skaperfestival 2017</a> -(Oslo Makers Festival) taking place today and tomorrow at Deichmanske -library. The solution is based on the -<a href="http://people.skolelinux.org/pere/blog/Easier_recipe_to_observe_the_cell_phones_around_you.html">simple -recipe for listening to GSM chatter</a> I posted a few days ago, and -will show up at the stand of <a href="http://sonen.ifi.uio.no/">Åpen -Sone from the Computer Science department of the University of -Oslo</a>. The presentation will show the nearby mobile phones (aka -IMSIs) as dots in a web browser graph, with lines to the dot -representing mobile base station it is talking to. It was working in -the lab yesterday, and was moved into place this morning.</p> - -<p>We set up a fairly powerful desktop machine using Debian -Buster/Testing with several (five, I believe) RTL2838 DVB-T receivers -connected and visualize the visible cell phone towers using an -<a href="https://github.com/marlow925/hopglass">English version of -Hopglass</a>. A fairly powerfull machine is needed as the -grgsm_livemon_headless processes from -<a href="https://tracker.debian.org/pkg/gr-gsm">gr-gsm</a> converting -the radio signal to data packages is quite CPU intensive.</p> - -<p>The frequencies to listen to, are identified using a slightly -patched scan-and-livemon (to set the --args values for each receiver), -and the Hopglass data is generated using the -<a href="https://github.com/petterreinholdtsen/IMSI-catcher/tree/meshviewer-output">patches -in my meshviewer-output branch</a>. For some reason we could not get -more than four SDRs working. There is also a geographical map trying -to show the location of the base stations, but I believe their -coordinates are hardcoded to some random location in Germany, I -believe. The code should be replaced with code to look up location in -a text file, a sqlite database or one of the online databases -mentioned in -<a href="https://github.com/Oros42/IMSI-catcher/issues/14">the github -issue for the topic</a>. - -<p>If this sound interesting, visit the stand at the festival!</p> + What is the most supported MIME type in Debian in 2018? + http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_in_2018_.html + http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_in_2018_.html + Mon, 9 Jul 2018 08:05:00 +0200 + <p>Five years ago, +<a href="http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_.html">I +measured what the most supported MIME type in Debian was</a>, by +analysing the desktop files in all packages in the archive. Since +then, the DEP-11 AppStream system has been put into production, making +the task a lot easier. This made me want to repeat the measurement, +to see how much things changed. Here are the new numbers, for +unstable only this time: + +<p><strong>Debian Unstable:</strong></p> + +<pre> + count MIME type + ----- ----------------------- + 56 image/jpeg + 55 image/png + 49 image/tiff + 48 image/gif + 39 image/bmp + 38 text/plain + 37 audio/mpeg + 34 application/ogg + 33 audio/x-flac + 32 audio/x-mp3 + 30 audio/x-wav + 30 audio/x-vorbis+ogg + 29 image/x-portable-pixmap + 27 inode/directory + 27 image/x-portable-bitmap + 27 audio/x-mpeg + 26 application/x-ogg + 25 audio/x-mpegurl + 25 audio/ogg + 24 text/html +</pre> + +<p>The list was created like this using a sid chroot: "cat +/var/lib/apt/lists/*sid*_dep11_Components-amd64.yml.gz| zcat | awk '/^ +- \S+\/\S+$/ {print $2 }' | sort | uniq -c | sort -nr | head -20"</p> + +<p>It is interesting to see how image formats have passed text/plain +as the most announced supported MIME type. These days, thanks to the +AppStream system, if you run into a file format you do not know, and +want to figure out which packages support the format, you can find the +MIME type of the file using "file --mime &lt;filename&gt;", and then +look up all packages announcing support for this format in their +AppStream metadata (XML or .desktop file) using "appstreamcli +what-provides mimetype &lt;mime-type&gt;. For example if you, like +me, want to know which packages support inode/directory, you can get a +list like this:</p> + +<p><blockquote><pre> +% appstreamcli what-provides mimetype inode/directory | grep Package: | sort +Package: anjuta +Package: audacious +Package: baobab +Package: cervisia +Package: chirp +Package: dolphin +Package: doublecmd-common +Package: easytag +Package: enlightenment +Package: ephoto +Package: filelight +Package: gwenview +Package: k4dirstat +Package: kaffeine +Package: kdesvn +Package: kid3 +Package: kid3-qt +Package: nautilus +Package: nemo +Package: pcmanfm +Package: pcmanfm-qt +Package: qweborf +Package: ranger +Package: sirikali +Package: spacefm +Package: spacefm +Package: vifm +% +</pre></blockquote></p> + +<p>Using the same method, I can quickly discover that the Sketchup file +format is not yet supported by any package in Debian:</p> + +<p><blockquote><pre> +% appstreamcli what-provides mimetype application/vnd.sketchup.skp +Could not find component providing 'mimetype::application/vnd.sketchup.skp'. +% +</pre></blockquote></p> + +<p>Yesterday I used it to figure out which packages support the STL 3D +format:</p> + +<p><blockquote><pre> +% appstreamcli what-provides mimetype application/sla|grep Package +Package: cura +Package: meshlab +Package: printrun +% +</pre></blockquote></p> + +<p>PS: A new version of Cura was uploaded to Debian yesterday.</p> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p> - Easier recipe to observe the cell phones around you - http://people.skolelinux.org/pere/blog/Easier_recipe_to_observe_the_cell_phones_around_you.html - http://people.skolelinux.org/pere/blog/Easier_recipe_to_observe_the_cell_phones_around_you.html - Sun, 24 Sep 2017 08:30:00 +0200 - <p>A little more than a month ago I wrote -<a href="http://people.skolelinux.org/pere/blog/Simpler_recipe_on_how_to_make_a_simple__7_IMSI_Catcher_using_Debian.html">how -to observe the SIM card ID (aka IMSI number) of mobile phones talking -to nearby mobile phone base stations using Debian GNU/Linux and a -cheap USB software defined radio</a>, and thus being able to pinpoint -the location of people and equipment (like cars and trains) with an -accuracy of a few kilometer. Since then we have worked to make the -procedure even simpler, and it is now possible to do this without any -manual frequency tuning and without building your own packages.</p> - -<p>The <a href="https://tracker.debian.org/pkg/gr-gsm">gr-gsm</a> -package is now included in Debian testing and unstable, and the -IMSI-catcher code no longer require root access to fetch and decode -the GSM data collected using gr-gsm.</p> - -<p>Here is an updated recipe, using packages built by Debian and a git -clone of two python scripts:</p> - -<ol> - -<li>Start with a Debian machine running the Buster version (aka - testing).</li> - -<li>Run '<tt>apt install gr-gsm python-numpy python-scipy - python-scapy</tt>' as root to install required packages.</li> - -<li>Fetch the code decoding GSM packages using '<tt>git clone - github.com/Oros42/IMSI-catcher.git</tt>'.</li> - -<li>Insert USB software defined radio supported by GNU Radio.</li> - -<li>Enter the IMSI-catcher directory and run '<tt>python - scan-and-livemon</tt>' to locate the frequency of nearby base - stations and start listening for GSM packages on one of them.</li> - -<li>Enter the IMSI-catcher directory and run '<tt>python - simple_IMSI-catcher.py</tt>' to display the collected information.</li> - -</ol> - -<p>Note, due to a bug somewhere the scan-and-livemon program (actually -<a href="https://github.com/ptrkrysik/gr-gsm/issues/336">its underlying -program grgsm_scanner</a>) do not work with the HackRF radio. It does -work with RTL 8232 and other similar USB radio receivers you can get -very cheaply -(<a href="https://www.ebay.com/sch/items/?_nkw=rtl+2832">for example -from ebay</a>), so for now the solution is to scan using the RTL radio -and only use HackRF for fetching GSM data.</p> - -<p>As far as I can tell, a cell phone only show up on one of the -frequencies at the time, so if you are going to track and count every -cell phone around you, you need to listen to all the frequencies used. -To listen to several frequencies, use the --numrecv argument to -scan-and-livemon to use several receivers. Further, I am not sure if -phones using 3G or 4G will show as talking GSM to base stations, so -this approach might not see all phones around you. I typically see -0-400 IMSI numbers an hour when looking around where I live.</p> - -<p>I've tried to run the scanner on a -<a href="https://wiki.debian.org/RaspberryPi">Raspberry Pi 2 and 3 -running Debian Buster</a>, but the grgsm_livemon_headless process seem -to be too CPU intensive to keep up. When GNU Radio print 'O' to -stdout, I am told there it is caused by a buffer overflow between the -radio and GNU Radio, caused by the program being unable to read the -GSM data fast enough. If you see a stream of 'O's from the terminal -where you started scan-and-livemon, you need a give the process more -CPU power. Perhaps someone are able to optimize the code to a point -where it become possible to set up RPi3 based GSM sniffers? I tried -using Raspbian instead of Debian, but there seem to be something wrong -with GNU Radio on raspbian, causing glibc to abort().</p> + Debian APT upgrade without enough free space on the disk... + http://people.skolelinux.org/pere/blog/Debian_APT_upgrade_without_enough_free_space_on_the_disk___.html + http://people.skolelinux.org/pere/blog/Debian_APT_upgrade_without_enough_free_space_on_the_disk___.html + Sun, 8 Jul 2018 12:10:00 +0200 + <p>Quite regularly, I let my Debian Sid/Unstable chroot stay untouch +for a while, and when I need to update it there is not enough free +space on the disk for apt to do a normal 'apt upgrade'. I normally +would resolve the issue by doing 'apt install &lt;somepackages&gt;' to +upgrade only some of the packages in one batch, until the amount of +packages to download fall below the amount of free space available. +Today, I had about 500 packages to upgrade, and after a while I got +tired of trying to install chunks of packages manually. I concluded +that I did not have the spare hours required to complete the task, and +decided to see if I could automate it. I came up with this small +script which I call 'apt-in-chunks':</p> + +<p><blockquote><pre> +#!/bin/sh +# +# Upgrade packages when the disk is too full to upgrade every +# upgradable package in one lump. Fetching packages to upgrade using +# apt, and then installing using dpkg, to avoid changing the package +# flag for manual/automatic. + +set -e + +ignore() { + if [ "$1" ]; then + grep -v "$1" + else + cat + fi +} + +for p in $(apt list --upgradable | ignore "$@" |cut -d/ -f1 | grep -v '^Listing...'); do + echo "Upgrading $p" + apt clean + apt install --download-only -y $p + for f in /var/cache/apt/archives/*.deb; do + if [ -e "$f" ]; then + dpkg -i /var/cache/apt/archives/*.deb + break + fi + done +done +</pre></blockquote></p> + +<p>The script will extract the list of packages to upgrade, try to +download the packages needed to upgrade one package, install the +downloaded packages using dpkg. The idea is to upgrade packages +without changing the APT mark for the package (ie the one recording of +the package was manually requested or pulled in as a dependency). To +use it, simply run it as root from the command line. If it fail, try +'apt install -f' to clean up the mess and run the script again. This +might happen if the new packages conflict with one of the old +packages. dpkg is unable to remove, while apt can do this.</p> + +<p>It take one option, a package to ignore in the list of packages to +upgrade. The option to ignore a package is there to be able to skip +the packages that are simply too large to unpack. Today this was +'ghc', but I have run into other large packages causing similar +problems earlier (like TeX).</p> + +<p>Update 2018-07-08: Thanks to Paul Wise, I am aware of two +alternative ways to handle this. The "unattended-upgrades +--minimal-upgrade-steps" option will try to calculate upgrade sets for +each package to upgrade, and then upgrade them in order, smallest set +first. It might be a better option than my above mentioned script. +Also, "aptutude upgrade" can upgrade single packages, thus avoiding +the need for using "dpkg -i" in the script above.</p> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p> - Datalagringsdirektivet kaster skygger over Høyre og Arbeiderpartiet - http://people.skolelinux.org/pere/blog/Datalagringsdirektivet_kaster_skygger_over_H_yre_og_Arbeiderpartiet.html - http://people.skolelinux.org/pere/blog/Datalagringsdirektivet_kaster_skygger_over_H_yre_og_Arbeiderpartiet.html - Thu, 7 Sep 2017 21:35:00 +0200 - <p>For noen dager siden publiserte Jon Wessel-Aas en bloggpost om -«<a href="http://www.uhuru.biz/?p=1821">Konklusjonen om datalagring som -EU-kommisjonen ikke ville at vi skulle få se</a>». Det er en -interessant gjennomgang av EU-domstolens syn på snurpenotovervåkning -av befolkningen, som er klar på at det er i strid med -EU-lovgivingen.</p> - -<p>Valgkampen går for fullt i Norge, og om noen få dager er siste -frist for å avgi stemme. En ting er sikkert, Høyre og Arbeiderpartiet -får ikke min stemme -<a href="http://people.skolelinux.org/pere/blog/Datalagringsdirektivet_gj_r_at_Oslo_H_yre_og_Arbeiderparti_ikke_f_r_min_stemme_i__r.html">denne -gangen heller</a>. Jeg har ikke glemt at de tvang igjennom loven som -skulle pålegge alle data- og teletjenesteleverandører å overvåke alle -sine kunder. En lov som er vedtatt, og aldri opphevet igjen.</p> - -<p>Det er tydelig fra diskusjonen rundt grenseløs digital overvåkning -(eller "Digital Grenseforsvar" som det kalles i Orvellisk nytale) at -hverken Høyre og Arbeiderpartiet har noen prinsipielle sperrer mot å -overvåke hele befolkningen, og diskusjonen så langt tyder på at flere -av de andre partiene heller ikke har det. Mange av -<a href="https://data.holderdeord.no/votes/1301946411e">de som stemte -for Datalagringsdirektivet i Stortinget</a> (64 fra Arbeiderpartiet, -25 fra Høyre) er fortsatt aktive og argumenterer fortsatt for å radere -vekk mer av innbyggernes privatsfære.</p> - -<p>Når myndighetene demonstrerer sin mistillit til folket, tror jeg -folket selv bør legge litt innsats i å verne sitt privatliv, ved å ta -i bruk ende-til-ende-kryptert kommunikasjon med sine kjente og kjære, -og begrense hvor mye privat informasjon som deles med uvedkommende. -Det er jo ingenting som tyder på at myndighetene kommer til å være vår -privatsfære. -<a href="http://people.skolelinux.org/pere/blog/How_to_talk_with_your_loved_ones_in_private.html">Det -er mange muligheter</a>. Selv har jeg litt sans for -<a href="https://ring.cx/">Ring</a>, som er basert på p2p-teknologi -uten sentral kontroll, er fri programvare, og støtter meldinger, tale -og video. Systemet er tilgjengelig ut av boksen fra -<a href="https://tracker.debian.org/pkg/ring">Debian</a> og -<a href="https://launchpad.net/ubuntu/+source/ring">Ubuntu</a>, og det -finnes pakker for Android, MacOSX og Windows. Foreløpig er det få -brukere med Ring, slik at jeg også bruker -<a href="https://signal.org/">Signal</a> som nettleserutvidelse.</p> + The worlds only stone power plant? + http://people.skolelinux.org/pere/blog/The_worlds_only_stone_power_plant_.html + http://people.skolelinux.org/pere/blog/The_worlds_only_stone_power_plant_.html + Sat, 30 Jun 2018 10:35:00 +0200 + <p>So far, at least hydro-electric power, coal power, wind power, +solar power, and wood power are well known. Until a few days ago, I +had never heard of stone power. Then I learn about a quarry in a +mountain in +<a href="https://en.wikipedia.org/wiki/Bremanger">Bremanger</a> i +Norway, where +<a href="https://www.bontrup.com/en/activities/raw-materials/bremanger-quarry/">the +Bremanger Quarry</a> company is extracting stone and dumping the stone +into a shaft leading to its shipping harbour. This downward movement +in this shaft is used to produce electricity. In short, it is using +falling rocks instead of falling water to produce electricity, and +according to its own statements it is producing more power than it is +using, and selling the surplus electricity to the Norwegian power +grid. I find the concept truly amazing. Is this the worlds only +stone power plant?</p> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p> - Simpler recipe on how to make a simple $7 IMSI Catcher using Debian - http://people.skolelinux.org/pere/blog/Simpler_recipe_on_how_to_make_a_simple__7_IMSI_Catcher_using_Debian.html - http://people.skolelinux.org/pere/blog/Simpler_recipe_on_how_to_make_a_simple__7_IMSI_Catcher_using_Debian.html - Wed, 9 Aug 2017 23:59:00 +0200 - <p>On friday, I came across an interesting article in the Norwegian -web based ICT news magazine digi.no on -<a href="https://www.digi.no/artikler/sikkerhetsforsker-lagde-enkel-imsi-catcher-for-60-kroner-na-kan-mobiler-kartlegges-av-alle/398588">how -to collect the IMSI numbers of nearby cell phones</a> using the cheap -DVB-T software defined radios. The article refered to instructions -and <a href="https://www.youtube.com/watch?v=UjwgNd_as30">a recipe by -Keld Norman on Youtube on how to make a simple $7 IMSI Catcher</a>, and I decided to test them out.</p> - -<p>The instructions said to use Ubuntu, install pip using apt (to -bypass apt), use pip to install pybombs (to bypass both apt and pip), -and the ask pybombs to fetch and build everything you need from -scratch. I wanted to see if I could do the same on the most recent -Debian packages, but this did not work because pybombs tried to build -stuff that no longer build with the most recent openssl library or -some other version skew problem. While trying to get this recipe -working, I learned that the apt->pip->pybombs route was a long detour, -and the only piece of software dependency missing in Debian was the -gr-gsm package. I also found out that the lead upstream developer of -gr-gsm (the name stand for GNU Radio GSM) project already had a set of -Debian packages provided in an Ubuntu PPA repository. All I needed to -do was to dget the Debian source package and built it.</p> - -<p>The IMSI collector is a python script listening for packages on the -loopback network device and printing to the terminal some specific GSM -packages with IMSI numbers in them. The code is fairly short and easy -to understand. The reason this work is because gr-gsm include a tool -to read GSM data from a software defined radio like a DVB-T USB stick -and other software defined radios, decode them and inject them into a -network device on your Linux machine (using the loopback device by -default). This proved to work just fine, and I've been testing the -collector for a few days now.</p> - -<p>The updated and simpler recipe is thus to</p> - -<ol> - -<li>start with a Debian machine running Stretch or newer,</li> - -<li>build and install the gr-gsm package available from -<a href="http://ppa.launchpad.net/ptrkrysik/gr-gsm/ubuntu/pool/main/g/gr-gsm/">http://ppa.launchpad.net/ptrkrysik/gr-gsm/ubuntu/pool/main/g/gr-gsm/</a>,</li> - -<li>clone the git repostory from <a href="https://github.com/Oros42/IMSI-catcher">https://github.com/Oros42/IMSI-catcher</a>,</li> - -<li>run grgsm_livemon and adjust the frequency until the terminal -where it was started is filled with a stream of text (meaning you -found a GSM station).</li> - -<li>go into the IMSI-catcher directory and run 'sudo python simple_IMSI-catcher.py' to extract the IMSI numbers.</li> - -</ol> - -<p>To make it even easier in the future to get this sniffer up and -running, I decided to package -<a href="https://github.com/ptrkrysik/gr-gsm/">the gr-gsm project</a> -for Debian (<a href="https://bugs.debian.org/871055">WNPP -#871055</a>), and the package was uploaded into the NEW queue today. -Luckily the gnuradio maintainer has promised to help me, as I do not -know much about gnuradio stuff yet.</p> - -<p>I doubt this "IMSI cacher" is anywhere near as powerfull as -commercial tools like -<a href="https://www.thespyphone.com/portable-imsi-imei-catcher/">The -Spy Phone Portable IMSI / IMEI Catcher</a> or the -<a href="https://en.wikipedia.org/wiki/Stingray_phone_tracker">Harris -Stingray</a>, but I hope the existance of cheap alternatives can make -more people realise how their whereabouts when carrying a cell phone -is easily tracked. Seeing the data flow on the screen, realizing that -I live close to a police station and knowing that the police is also -wearing cell phones, I wonder how hard it would be for criminals to -track the position of the police officers to discover when there are -police near by, or for foreign military forces to track the location -of the Norwegian military forces, or for anyone to track the location -of government officials...</p> - -<p>It is worth noting that the data reported by the IMSI-catcher -script mentioned above is only a fraction of the data broadcasted on -the GSM network. It will only collect one frequency at the time, -while a typical phone will be using several frequencies, and not all -phones will be using the frequencies tracked by the grgsm_livemod -program. Also, there is a lot of radio chatter being ignored by the -simple_IMSI-catcher script, which would be collected by extending the -parser code. I wonder if gr-gsm can be set up to listen to more than -one frequency?</p> + Add-on to control the projector from within Kodi + http://people.skolelinux.org/pere/blog/Add_on_to_control_the_projector_from_within_Kodi.html + http://people.skolelinux.org/pere/blog/Add_on_to_control_the_projector_from_within_Kodi.html + Tue, 26 Jun 2018 23:55:00 +0200 + <p>My movie playing setup involve <a href="https://kodi.tv/">Kodi</a>, +<a href="https://openelec.tv">OpenELEC</a> (probably soon to be +replaced with <a href="https://libreelec.tv/">LibreELEC</a>) and an +Infocus IN76 video projector. My projector can be controlled via both +a infrared remote controller, and a RS-232 serial line. The vendor of +my projector, <a href="https://www.infocus.com/">InFocus</a>, had been +sensible enough to document the serial protocol in its user manual, so +it is easily available, and I used it some years ago to write +<a href="https://github.com/petterreinholdtsen/infocus-projector-control">a +small script to control the projector</a>. For a while now, I longed +for a setup where the projector was controlled by Kodi, for example in +such a way that when the screen saver went on, the projector was +turned off, and when the screen saver exited, the projector was turned +on again.</p> + +<p>A few days ago, with very good help from parts of my family, I +managed to find a Kodi Add-on for controlling a Epson projector, and +got in touch with its author to see if we could join forces and make a +Add-on with support for several projectors. To my pleasure, he was +positive to the idea, and we set out to add InFocus support to his +add-on, and make the add-on suitable for the official Kodi add-on +repository.</p> + +<p>The Add-on is now working (for me, at least), with a few minor +adjustments. The most important change I do relative to the master +branch in the github repository is embedding the +<a href="https://github.com/pyserial/pyserial">pyserial module</a> in +the add-on. The long term solution is to make a "script" type +pyserial module for Kodi, that can be pulled in as a dependency in +Kodi. But until that in place, I embed it.</p> + +<p>The add-on can be configured to turn on the projector when Kodi +starts, off when Kodi stops as well as turn the projector off when the +screensaver start and on when the screesaver stops. It can also be +told to set the projector source when turning on the projector. + +<p>If this sound interesting to you, check out +<a href="https://github.com/fredrik-eriksson/kodi_projcontrol">the +project github repository</a>. Perhaps you can send patches to +support your projector too? As soon as we find time to wrap up the +latest changes, it should be available for easy installation using any +Kodi instance.</p> + +<p>For future improvements, I would like to add projector model +detection and the ability to adjust the brightness level of the +projector from within Kodi. We also need to figure out how to handle +the cooling period of the projector. My projector refuses to turn on +for 60 seconds after it was turned off. This is not handled well by +the add-on at the moment.</p> + +<p>As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>