X-Git-Url: http://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/b6b6575e368fa0e8d3ac34a3a09aa1e21132be0e..bb38026f1c7da4cc23680c02a66d2912d2925a58:/blog/index.html diff --git a/blog/index.html b/blog/index.html index 7cee2eb902..2bdeeec807 100644 --- a/blog/index.html +++ b/blog/index.html @@ -20,83 +20,148 @@
-
Some notes on fault tolerant storage systems
-
1st November 2017
-

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.

- - - -

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.

- -

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.

+
Streaming the Linux desktop to Kodi using VLC and RTSP
+
12th July 2018
+

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.

+ +

I had a look at several approaches, for example +using uPnP +DLNA as described in 2011, 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.

+ +

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.

+ +

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.

+ +

I did not spend much time investigating codeces. I combined the +rtp and rtsp recipes from +the +VLC Streaming HowTo/Command Line Examples, and was able to get +this working on the desktop/streaming end.

+ +
+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}'
+
+ +

I ssh-ed into my Kodi box and created a file like this with the +same IP address:

+ +
+echo rtsp://192.168.11.4:8080/test.sdp \
+  > /storage/videos/screenstream.m3u
+
+ +

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. :)

+ +

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.

+ +

Update 2018-07-12: 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 + +

+cvlc screen:// --sout \
+  '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{sdp=rtsp://:8080/}'
+
+ +

and this on the Kodi end

+ +

+echo rtsp://192.168.11.4:8080/ \
+  > /storage/videos/screenstream.m3u
+
+ +

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.

+ +

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: + +

+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.
+
+ +

and this on the Kodi end

+ +

+echo udp://@239.255.0.1:1234 \
+  > /storage/videos/screenstream.m3u
+
+ +

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. :)!

+ +

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.

+ +
+cvlc screen:// --sout '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{mux=ts,dst=239.255.0.1,port=1234,sdp=sap}'
+
+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

- Tags: english, raid, sysadmin. + Tags: debian, english, video.
@@ -104,46 +169,121 @@ status to detect and replace failed disks.

-
Web services for writing academic LaTeX papers as a team
-
31st October 2017
-

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.

- -

There are two commercial services available, -ShareLaTeX and -Overleaf. 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 -ShareLaTeX is free -software, while the latter is not. According to a -announcement from Overleaf, they plan to keep the ShareLaTeX code -base maintained as free software.

- -But these two are not the only alternatives. -Fidus Writer is another free -software solution with the -source available on github. I have not used it myself. Several -others can be found on the nice -alterntiveTo -web service. - -

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. :)

- +
What is the most supported MIME type in Debian in 2018?
+
9th July 2018
+

Five years ago, +I +measured what the most supported MIME type in Debian was, 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: + +

Debian Unstable:

+ +
+  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
+
+ +

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"

+ +

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 <filename>", and then +look up all packages announcing support for this format in their +AppStream metadata (XML or .desktop file) using "appstreamcli +what-provides mimetype <mime-type>. For example if you, like +me, want to know which packages support inode/directory, you can get a +list like this:

+ +

+% 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
+%
+

+ +

Using the same method, I can quickly discover that the Sketchup file +format is not yet supported by any package in Debian:

+ +

+% appstreamcli what-provides mimetype  application/vnd.sketchup.skp
+Could not find component providing 'mimetype::application/vnd.sketchup.skp'.
+%
+

+ +

Yesterday I used it to figure out which packages support the STL 3D +format:

+ +

+% appstreamcli what-provides mimetype  application/sla|grep Package
+Package: cura
+Package: meshlab
+Package: printrun
+%
+

+ +

PS: A new version of Cura was uploaded to Debian yesterday.

+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

- Tags: english. + Tags: debian, english, isenkram.
@@ -151,288 +291,83 @@ host your own, if you want to. :)

-
Locating IMDB IDs of movies in the Internet Archive using Wikidata
-
25th October 2017
-

Recently, I needed to automatically check the copyright status of a -set of The Internet Movie database -(IMDB) 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.

- -

First I tried to look up entries manually in IMDB, -Wikipedia and -The Internet Archive, 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.

- -

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.

- -

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 the SPARQL interface on -Wikidata: - -

-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").
-  }
+      
Debian APT upgrade without enough free space on the disk...

+      
 8th July 2018

+      
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 <somepackages>' 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':

+
+
+#!/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
 }
-

-
-
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.

-
-
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.

-
-
This is not too bad, given that The Internet Archive report to
-contain 5331
-feature films at the moment, but it also mean more than 3000
-movies are missing on Wikipedia or are missing the pair of references
-on Wikipedia.

-
-
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:

-
-

-
-
I expect the relative distribution of the remaining 3000 movies to
-be similar.

-
-
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:

-
-
-* {{Internet Archive film|id=FightingLady}}
-* {{IMDb title|id=0036823|title=The Fighting Lady}}
-

 
-
Please verify the links on the final page, to make sure you did not
-introduce a typo.

-
-
Here is the complete list, if you want to correct the 171
-identified Wikipedia entries with broken links to The Internet
-Archive: Q1140317, 
-Q458656, 
-Q458656, 
-Q470560, 
-Q743340, 
-Q822580, 
-Q480696, 
-Q128761, 
-Q1307059, 
-Q1335091, 
-Q1537166, 
-Q1438334, 
-Q1479751, 
-Q1497200, 
-Q1498122, 
-Q865973, 
-Q834269, 
-Q841781, 
-Q841781, 
-Q1548193, 
-Q499031, 
-Q1564769, 
-Q1585239, 
-Q1585569, 
-Q1624236, 
-Q4796595, 
-Q4853469, 
-Q4873046, 
-Q915016, 
-Q4660396, 
-Q4677708, 
-Q4738449, 
-Q4756096, 
-Q4766785, 
-Q880357, 
-Q882066, 
-Q882066, 
-Q204191, 
-Q204191, 
-Q1194170, 
-Q940014, 
-Q946863, 
-Q172837, 
-Q573077, 
-Q1219005, 
-Q1219599, 
-Q1643798, 
-Q1656352, 
-Q1659549, 
-Q1660007, 
-Q1698154, 
-Q1737980, 
-Q1877284, 
-Q1199354, 
-Q1199354, 
-Q1199451, 
-Q1211871, 
-Q1212179, 
-Q1238382, 
-Q4906454, 
-Q320219, 
-Q1148649, 
-Q645094, 
-Q5050350, 
-Q5166548, 
-Q2677926, 
-Q2698139, 
-Q2707305, 
-Q2740725, 
-Q2024780, 
-Q2117418, 
-Q2138984, 
-Q1127992, 
-Q1058087, 
-Q1070484, 
-Q1080080, 
-Q1090813, 
-Q1251918, 
-Q1254110, 
-Q1257070, 
-Q1257079, 
-Q1197410, 
-Q1198423, 
-Q706951, 
-Q723239, 
-Q2079261, 
-Q1171364, 
-Q617858, 
-Q5166611, 
-Q5166611, 
-Q324513, 
-Q374172, 
-Q7533269, 
-Q970386, 
-Q976849, 
-Q7458614, 
-Q5347416, 
-Q5460005, 
-Q5463392, 
-Q3038555, 
-Q5288458, 
-Q2346516, 
-Q5183645, 
-Q5185497, 
-Q5216127, 
-Q5223127, 
-Q5261159, 
-Q1300759, 
-Q5521241, 
-Q7733434, 
-Q7736264, 
-Q7737032, 
-Q7882671, 
-Q7719427, 
-Q7719444, 
-Q7722575, 
-Q2629763, 
-Q2640346, 
-Q2649671, 
-Q7703851, 
-Q7747041, 
-Q6544949, 
-Q6672759, 
-Q2445896, 
-Q12124891, 
-Q3127044, 
-Q2511262, 
-Q2517672, 
-Q2543165, 
-Q426628, 
-Q426628, 
-Q12126890, 
-Q13359969, 
-Q13359969, 
-Q2294295, 
-Q2294295, 
-Q2559509, 
-Q2559912, 
-Q7760469, 
-Q6703974, 
-Q4744, 
-Q7766962, 
-Q7768516, 
-Q7769205, 
-Q7769988, 
-Q2946945, 
-Q3212086, 
-Q3212086, 
-Q18218448, 
-Q18218448, 
-Q18218448, 
-Q6909175, 
-Q7405709, 
-Q7416149, 
-Q7239952, 
-Q7317332, 
-Q7783674, 
-Q7783704, 
-Q7857590, 
-Q3372526, 
-Q3372642, 
-Q3372816, 
-Q3372909, 
-Q7959649, 
-Q7977485, 
-Q7992684, 
-Q3817966, 
-Q3821852, 
-Q3420907, 
-Q3429733, 
-Q774474

+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
+

+ +

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.

+ +

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).

+ +

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.

+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

- Tags: english, opphavsrett. + Tags: debian, english.
@@ -440,21 +375,27 @@ Archive: Q1140317,
-
A one-way wall on the border?
-
14th October 2017
-

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 -the -propaganda twist from the East Germany government 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.

- -

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?

+
The worlds only stone power plant?
+
30th June 2018
+

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 +Bremanger i +Norway, where +the +Bremanger Quarry 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?

+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

@@ -467,48 +408,66 @@ while not keeping people in the inside from getting out?

-
Generating 3D prints in Debian using Cura and Slic3r(-prusa)
-
9th October 2017
-

At my nearby maker space, -Sonen, 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, -Cura, 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 request for adding into -Debian 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.

- -

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 -the -status page for the 3D printer team.

- -

The uploaded packages are a bit behind upstream, and was uploaded -now to get slots in the NEW -queue while we work up updating the packages to the latest -upstream version.

- -

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 -slic3r and -slic3r-prusa. -The latter is a fork of the former.

+
Add-on to control the projector from within Kodi
+
26th June 2018
+

My movie playing setup involve Kodi, +OpenELEC (probably soon to be +replaced with LibreELEC) 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, InFocus, 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 +small script to control the projector. 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.

+ +

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.

+ +

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 +pyserial module 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.

+ +

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. + +

If this sound interesting to you, check out +the +project github repository. 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.

+ +

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.

+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

- Tags: 3d-printer, debian, english. + Tags: english, multimedia, video.
@@ -516,30 +475,71 @@ The latter is a fork of the former.

-
Mangler du en skrue, eller har du en skrue løs?
-
4th October 2017
-
Når jeg holder på med ulike prosjekter, så trenger jeg stadig ulike -skruer. Det siste prosjektet jeg holder på med er å lage -en boks til en -HDMI-touch-skjerm 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. -Zachariassen Jernvare AS i -Hegermannsgate -23A på Torshov 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. :)

+
youtube-dl for nedlasting fra NRK med undertekster - nice free software
+
28th April 2018
+

I VHS-kassettenes +tid var det rett frem å ta vare på et TV-program en ønsket å kunne se +senere, uten å være avhengig av at programmet ble sendt på nytt. +Kanskje ønsket en å se programmet på hytten der det ikke var +TV-signal, eller av andre grunner ha det tilgjengelig for fremtidig +fornøyelse. Dette er blitt vanskeligere med introduksjon av +digital-TV og webstreaming, der opptak til harddisk er utenfor de +flestes kontroll hvis de bruker ufri programvare og bokser kontrollert +av andre. Men for NRK her i Norge, finnes det heldigvis flere fri +programvare-alternativer, som jeg har +skrevet +om +før. +Så lenge kilden for nedlastingen er lovlig lagt ut på nett (hvilket +jeg antar NRK gjør), så er slik lagring til privat bruk også lovlig i +Norge.

+ +

Sist jeg så på saken, i 2016, nevnte jeg at +youtube-dl ikke kunne +bake undertekster fra NRK inn i videofilene, og at jeg derfor +foretrakk andre alternativer. Nylig oppdaget jeg at dette har endret +seg. Fordelen med youtube-dl er at den er tilgjengelig direkte fra +Linux-distribusjoner som Debian +og Ubuntu, slik at en slipper å +finne ut selv hvordan en skal få dem til å virke.

+ +

For å laste ned et NRK-innslag med undertekster, og få den norske +underteksten pakket inn i videofilen, så kan følgende kommando +brukes:

+ +

+youtube-dl --write-sub --sub-format ttml \
+  --convert-subtitles srt --embed-subs \
+  https://tv.nrk.no/serie/ramm-ferdig-gaa/MUHU11000316/27-04-2018
+

+ +

URL-eksemplet er dagens toppsak på tv.nrk.no. Resultatet er en +MP4-fil med filmen og undertekster som kan spilles av med VLC. Merk +at VLC ikke viser frem undertekster før du aktiverer dem. For å gjøre +det, høyreklikk med musa i fremviservinduet, velg menyvalget for +undertekst og så norsk språk. Jeg testet også '--write-auto-sub', +men det kommandolinjeargumentet ser ikke ut til å fungere, så jeg +endte opp med settet med argumentlisten over, som jeg fant i en +feilrapport i youtube-dl-prosjektets samling over feilrapporter.

+ +

Denne støtten i youtube-dl gjør det svært enkelt å lagre +NRK-innslag, det være seg nyheter, filmer, serier eller dokumentater, +for å ha dem tilgjengelig for fremtidig referanse og bruk, uavhengig +av hvor lenge innslagene ligger tilgjengelig hos NRK. Så får det ikke +hjelpe at NRKs jurister mener at det er +vesensforskjellig +å legge tilgjengelig for nedlasting og for streaming, når det rent +teknisk er samme sak.

+ +

Programmet youtube-dl støtter også en rekke andre nettsteder, se +prosjektoversikten for +en +komplett liste.

- Tags: norsk. + Tags: multimedia, nice free software, norsk, video, web.
@@ -547,64 +547,27 @@ nabolaget for oss som liker å bygge litt selv. :)

-
Visualizing GSM radio chatter using gr-gsm and Hopglass
-
29th September 2017
-

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.

- -

I am very happy to report that we managed to get something -visualizing this information up and running for -Oslo Skaperfestival 2017 -(Oslo Makers Festival) taking place today and tomorrow at Deichmanske -library. The solution is based on the -simple -recipe for listening to GSM chatter I posted a few days ago, and -will show up at the stand of Åpen -Sone from the Computer Science department of the University of -Oslo. 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.

- -

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 -English version of -Hopglass. A fairly powerfull machine is needed as the -grgsm_livemon_headless processes from -gr-gsm converting -the radio signal to data packages is quite CPU intensive.

- -

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 -patches -in my meshviewer-output branch. 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 -the github -issue for the topic. - -

If this sound interesting, visit the stand at the festival!

+
Stortingsflertallet går inn for ny IP-basert sensurinfrastruktur i Norge
+
24th April 2018
+

VG, +Dagbladet +og +NRK +melder i dag at flertallet i Familie- og kulturkomiteen på Stortinget +har bestemt seg for å introdusere en ny sensurinfrastruktur i Norge. +Fra før har Norge en «frivillig» sensurinfrastruktur basert på +DNS-navn, der de største ISP-ene basert på en liste med DNS-navn +forgifter DNS-svar og omdirigerer til et annet IP-nummer enn det som +ligger i DNS. Nå kommer altså IP-basert omdirigering i tillegg. Når +infrastrukturen er på plass, er sensur av IP-adresser redusert et +spørsmål om hvilke IP-nummer som skal blokkeres. Listen over +IP-adresser vil naturligvis endre seg etter hvert som myndighetene +endrer seg. Det er ingen betryggende tanke.

- Tags: debian, english, personvern, surveillance. + Tags: norsk, sikkerhet.
@@ -612,83 +575,40 @@ issue for the topic.
-
Easier recipe to observe the cell phones around you
-
24th September 2017
-

A little more than a month ago I wrote -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, 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.

- -

The gr-gsm -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.

- -

Here is an updated recipe, using packages built by Debian and a git -clone of two python scripts:

- -
    - -
  1. Start with a Debian machine running the Buster version (aka - testing).
    2. - -
  2. Run 'apt install gr-gsm python-numpy python-scipy - python-scapy' as root to install required packages.
    3. - -
  3. Fetch the code decoding GSM packages using 'git clone - github.com/Oros42/IMSI-catcher.git'.
    4. - -
  4. Insert USB software defined radio supported by GNU Radio.
    5. - -
  5. Enter the IMSI-catcher directory and run 'python - scan-and-livemon' to locate the frequency of nearby base - stations and start listening for GSM packages on one of them.
    6. - -
  6. Enter the IMSI-catcher directory and run 'python - simple_IMSI-catcher.py' to display the collected information.
    7. - -
- -

Note, due to a bug somewhere the scan-and-livemon program (actually -its underlying -program grgsm_scanner) do not work with the HackRF radio. It does -work with RTL 8232 and other similar USB radio receivers you can get -very cheaply -(for example -from ebay), so for now the solution is to scan using the RTL radio -and only use HackRF for fetching GSM data.

- -

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.

- -

I've tried to run the scanner on a -Raspberry Pi 2 and 3 -running Debian Buster, 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().

+
En grunn til å takke nei til usikker digital post
+
2nd April 2018
+

Brevpost er beskyttet av straffelovens bestemmelse som gjør det +kriminelt å åpne andres brev. Dette følger av (ny) straffelovs +§ 205 +(Krenkelse av retten til privat kommunikasjon), som sier at «Med +bot eller fengsel inntil 2 år straffes den som uberettiget ... c) +åpner brev eller annen lukket skriftlig meddelelse som er adressert +til en annen, eller på annen måte skaffer seg uberettiget tilgang til +innholdet.» Dette gjelder såvel postbud som alle andre som har +befatning med brevet etter at avsender har befatning med et lukket +brev. Tilsvarende står også tidligere utgaver av den norske +straffeloven.

+ +

Når en registrerer seg på usikre digitale postkasseløsningene, som +f.eks. Digipost og e-Boks, og slik tar disse i bruk, så gir en de som +står bak løsningene tillatelse til å åpne sine brev. Dette er +nødvendig for at innholdet i digital post skal kunne vises frem til +mottaker via tjenestens websider. Dermed gjelder ikke straffelovens +paragraf om forbud mot å åpne brev, da tilgangen ikke lenger er +uberettiget. En gir altså fremmede tilgang til å lese sin +korrespondanse. I tillegg vil bruk av slike usikre digitale +postbokser føre til at det blir registrert når du leser brevene, hvor +du befinner deg (vha. tilkoblingens IP-adresse), hvilket utstyr du +bruker og en rekke annen personlig informasjon som ikke er +tilgjengelig når papirpost brukes. Jeg foretrekker at det er +lovmessig beskyttelse av min korrespondanse, som jo inneholder privat +og personlig informasjon. Det bidrar til litt bedre vern av personlig +integritet i dagens norske samfunn.

- Tags: debian, english, personvern, surveillance. + Tags: norsk, personvern, surveillance.
@@ -696,54 +616,34 @@ with GNU Radio on raspbian, causing glibc to abort().

-
Datalagringsdirektivet kaster skygger over Høyre og Arbeiderpartiet
-
7th September 2017
-

For noen dager siden publiserte Jon Wessel-Aas en bloggpost om -«Konklusjonen om datalagring som -EU-kommisjonen ikke ville at vi skulle få se». 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.

- -

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 -denne -gangen heller. 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.

- -

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 -de som stemte -for Datalagringsdirektivet i Stortinget (64 fra Arbeiderpartiet, -25 fra Høyre) er fortsatt aktive og argumenterer fortsatt for å radere -vekk mer av innbyggernes privatsfære.

- -

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. -Det -er mange muligheter. Selv har jeg litt sans for -Ring, 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 -Debian og -Ubuntu, og det -finnes pakker for Android, MacOSX og Windows. Foreløpig er det få -brukere med Ring, slik at jeg også bruker -Signal som nettleserutvidelse.

+
Self-appointed leaders of the Free World
+
22nd March 2018
+

The leaders of the worlds have started to congratulate the +re-elected Russian head of state, and this causes some criticism. I +am though a little fascinated by a comment from USA senator John McCain, +sited +by The Hill and others: + +

+

"An American president does not lead the Free World by +congratulating dictators on winning sham elections."

+

+ +

While I totally agree with the senator here, the way the quote is +phrased make me suspect that he is unaware of the simple fact that USA +have not lead the Free World since at least before its government +kidnapped a +completely innocent Canadian citizen in transit on his way home to +Canada via John F. Kennedy International Airport in September 2002 and +sent him to be tortured in Syria for a year.

+ +

USA might be running ahead, but the path they are taking is not the +one taken by any Free World.

- Tags: dld, norsk, personvern, stortinget, surveillance, valg. + Tags: english.
@@ -751,96 +651,63 @@ brukere med Ring, slik at jeg også bruker
-
Simpler recipe on how to make a simple $7 IMSI Catcher using Debian
-
9th August 2017
-

On friday, I came across an interesting article in the Norwegian -web based ICT news magazine digi.no on -how -to collect the IMSI numbers of nearby cell phones using the cheap -DVB-T software defined radios. The article refered to instructions -and a recipe by -Keld Norman on Youtube on how to make a simple $7 IMSI Catcher, and I decided to test them out.

- -

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.

- -

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.

- -

The updated and simpler recipe is thus to

- -
    - -
  1. start with a Debian machine running Stretch or newer,
    2. - -
  2. build and install the gr-gsm package available from -http://ppa.launchpad.net/ptrkrysik/gr-gsm/ubuntu/pool/main/g/gr-gsm/,
    3. - -
  3. clone the git repostory from https://github.com/Oros42/IMSI-catcher,
    4. - -
  4. 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).
    5. - -
  5. go into the IMSI-catcher directory and run 'sudo python simple_IMSI-catcher.py' to extract the IMSI numbers.
    6. - -
- -

To make it even easier in the future to get this sniffer up and -running, I decided to package -the gr-gsm project -for Debian (WNPP -#871055), 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.

- -

I doubt this "IMSI cacher" is anywhere near as powerfull as -commercial tools like -The -Spy Phone Portable IMSI / IMEI Catcher or the -Harris -Stingray, 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...

- -

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?

+
Facebooks ability to sell your personal information is the real Cambridge Analytica scandal
+
21st March 2018
+

So, Cambridge Analytica is getting some well deserved criticism for +(mis)using information it got from Facebook about 50 million people, +mostly in the USA. What I find a bit surprising, is how little +criticism Facebook is getting for handing the information over to +Cambridge Analytica and others in the first place. And what about the +people handing their private and personal information to Facebook? +And last, but not least, what about the government offices who are +handing information about the visitors of their web pages to Facebook? +No-one who looked at the terms of use of Facebook should be surprised +that information about peoples interests, political views, personal +lifes and whereabouts would be sold by Facebook.

+ +

What I find to be the real scandal is the fact that Facebook is +selling your personal information, not that one of the buyers used it +in a way Facebook did not approve when exposed. It is well known that +Facebook is selling out their users privacy, but a scandal +nevertheless. Of course the information provided to them by Facebook +would be misused by one of the parties given access to personal +information about the millions of Facebook users. Collected +information will be misused sooner or later. The only way to avoid +such misuse, is to not collect the information in the first place. If +you do not want Facebook to hand out information about yourself for +the use and misuse of its customers, do not give Facebook the +information.

+ +

Personally, I would recommend to completely remove your Facebook +account, and take back some control of your personal information. +According +to The Guardian, it is a bit hard to find out how to request +account removal (and not just 'disabling'). You need to +visit +a specific Facebook page and click on 'let us know' on that page +to get to the +real account deletion screen. Perhaps something to consider? I +would not trust the information to really be deleted (who knows, +perhaps NSA, GCHQ and FRA already got a copy), but it might reduce the +exposure a bit.

+ +

If you want to learn more about the capabilities of Cambridge +Analytica, I recommend to see the video recording of the one hour talk +Paul-Olivier Dehaye gave to NUUG last april about + +Data collection, psychometric profiling and their impact on +politics.

+ +

And if you want to communicate with your friends and loved ones, +use some end-to-end encrypted method like +Signal or +Ring, and stop sharing your private +messages with strangers like Facebook and Google.

- Tags: debian, english, personvern, surveillance. + Tags: english, personvern.
@@ -855,6 +722,23 @@ one frequency?

Archive