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        <channel>
                <title>Petter Reinholdtsen</title>
                <description></description>
                <link>http://people.skolelinux.org/pere/blog/</link>
                <atom:link href="http://people.skolelinux.org/pere/blog/index.rss" rel="self" type="application/rss+xml" />
        
        <item>
                <title>Some notes on fault tolerant storage systems</title>
                <link>http://people.skolelinux.org/pere/blog/Some_notes_on_fault_tolerant_storage_systems.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Some_notes_on_fault_tolerant_storage_systems.html</guid>
                <pubDate>Wed, 1 Nov 2017 15:35:00 +0100</pubDate>
                <description>&lt;p&gt;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.&lt;/p&gt;

&lt;ul&gt;

&lt;li&gt;USENIX :login; &lt;a
href=&quot;https://www.usenix.org/publications/login/summer2017/ganesan&quot;&gt;Redundancy
Does Not Imply Fault Tolerance.  Analysis of Distributed Storage
Reactions to Single Errors and Corruptions&lt;/a&gt; by Aishwarya Ganesan,
Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, and Remzi
H. Arpaci-Dusseau&lt;/li&gt;

&lt;li&gt;ZDNet
&lt;a href=&quot;http://www.zdnet.com/article/why-raid-5-stops-working-in-2009/&quot;&gt;Why
RAID 5 stops working in 2009&lt;/a&gt; by Robin Harris&lt;/li&gt;

&lt;li&gt;ZDNet
&lt;a href=&quot;http://www.zdnet.com/article/why-raid-6-stops-working-in-2019/&quot;&gt;Why
RAID 6 stops working in 2019&lt;/a&gt; by Robin Harris&lt;/li&gt;

&lt;li&gt;USENIX FAST&#39;07
&lt;a href=&quot;http://research.google.com/archive/disk_failures.pdf&quot;&gt;Failure
Trends in a Large Disk Drive Population&lt;/a&gt; by Eduardo Pinheiro,
Wolf-Dietrich Weber and Luiz André Barroso&lt;/li&gt;

&lt;li&gt;USENIX ;login: &lt;a
href=&quot;https://www.usenix.org/system/files/login/articles/hughes12-04.pdf&quot;&gt;Data
Integrity.  Finding Truth in a World of Guesses and Lies&lt;/a&gt; by Doug
Hughes&lt;/li&gt;

&lt;li&gt;USENIX FAST&#39;08
&lt;a href=&quot;https://www.usenix.org/events/fast08/tech/full_papers/bairavasundaram/bairavasundaram_html/&quot;&gt;An
Analysis of Data Corruption in the Storage Stack&lt;/a&gt; by
L. N. Bairavasundaram, G. R. Goodson, B. Schroeder, A. C.
Arpaci-Dusseau, and R. H. Arpaci-Dusseau&lt;/li&gt;

&lt;li&gt;USENIX FAST&#39;07 &lt;a
href=&quot;https://www.usenix.org/legacy/events/fast07/tech/schroeder/schroeder_html/&quot;&gt;Disk
failures in the real world: what does an MTTF of 1,000,000 hours mean
to you?&lt;/a&gt; by B. Schroeder and G. A. Gibson.&lt;/li&gt;

&lt;li&gt;USENIX ;login: &lt;a
href=&quot;https://www.usenix.org/events/fast08/tech/full_papers/jiang/jiang_html/&quot;&gt;Are
Disks the Dominant Contributor for Storage Failures?  A Comprehensive
Study of Storage Subsystem Failure Characteristics&lt;/a&gt; by Weihang
Jiang, Chongfeng Hu, Yuanyuan Zhou, and Arkady Kanevsky&lt;/li&gt;

&lt;li&gt;SIGMETRICS 2007
&lt;a href=&quot;http://research.cs.wisc.edu/adsl/Publications/latent-sigmetrics07.pdf&quot;&gt;An
analysis of latent sector errors in disk drives&lt;/a&gt; by
L. N. Bairavasundaram, G. R. Goodson, S. Pasupathy, and J. Schindler&lt;/li&gt;

&lt;/ul&gt;

&lt;p&gt;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, there is an old saying, you know
you have a distributed system when the crash of a computer you have
never heard of stops you from getting any work done.  The same holds
true if fault tolerance do not work.&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Web services for writing academic LaTeX papers as a team</title>
                <link>http://people.skolelinux.org/pere/blog/Web_services_for_writing_academic_LaTeX_papers_as_a_team.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Web_services_for_writing_academic_LaTeX_papers_as_a_team.html</guid>
                <pubDate>Tue, 31 Oct 2017 21:00:00 +0100</pubDate>
                <description>&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;There are two commercial services available,
&lt;a href=&quot;https://sharelatex.com&quot;&gt;ShareLaTeX&lt;/a&gt; and
&lt;a href=&quot;https://overleaf.com&quot;&gt;Overleaf&lt;/a&gt;.  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&#39;ve used both for different documents, and they
work just fine.  While
&lt;a href=&quot;https://github.com/sharelatex/sharelatex&quot;&gt;ShareLaTeX is free
software&lt;/a&gt;, while the latter is not.  According to &lt;a
href=&quot;https://www.overleaf.com/help/17-is-overleaf-open-source&quot;&gt;a
announcement from Overleaf&lt;/a&gt;, they plan to keep the ShareLaTeX code
base maintained as free software.&lt;/p&gt;

But these two are not the only alternatives.
&lt;a href=&quot;https://app.fiduswriter.org/&quot;&gt;Fidus Writer&lt;/a&gt; is another free
software solution with &lt;a href=&quot;https://github.com/fiduswriter&quot;&gt;the
source available on github&lt;/a&gt;.  I have not used it myself.  Several
others can be found on the nice
&lt;a href=&quot;https://alternativeto.net/software/sharelatex/&quot;&gt;alterntiveTo
web service&lt;/a&gt;.

&lt;p&gt;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. :)&lt;/p&gt;

</description>
        </item>
        
        <item>
                <title>Locating IMDB IDs of movies in the Internet Archive using Wikidata</title>
                <link>http://people.skolelinux.org/pere/blog/Locating_IMDB_IDs_of_movies_in_the_Internet_Archive_using_Wikidata.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Locating_IMDB_IDs_of_movies_in_the_Internet_Archive_using_Wikidata.html</guid>
                <pubDate>Wed, 25 Oct 2017 12:20:00 +0200</pubDate>
                <description>&lt;p&gt;Recently, I needed to automatically check the copyright status of a
set of &lt;a href=&quot;http://www.imdb.com/&quot;&gt;The Internet Movie database
(IMDB)&lt;/a&gt; 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.&lt;/p&gt;

&lt;p&gt;First I tried to look up entries manually in IMDB,
&lt;a href=&quot;https://www.wikipedia.org/&quot;&gt;Wikipedia&lt;/a&gt; and
&lt;a href=&quot;https://www.archive.org/&quot;&gt;The Internet Archive&lt;/a&gt;, 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 &quot;out
of copyright&quot; 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.&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;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 &lt;a href=&quot;https://query.wikidata.org/&quot;&gt;the SPARQL interface on
Wikidata&lt;/a&gt;:

&lt;p&gt;&lt;pre&gt;
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) = &quot;en&quot;).
  }
}
&lt;/pre&gt;&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;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 &quot;disappearing&quot;
entries (ie 2338-2097-171) are duplicate entries.&lt;/p&gt;

&lt;p&gt;This is not too bad, given that The Internet Archive report to
contain &lt;a href=&quot;https://archive.org/details/feature_films&quot;&gt;5331
feature films&lt;/a&gt; at the moment, but it also mean more than 3000
movies are missing on Wikipedia or are missing the pair of references
on Wikipedia.&lt;/p&gt;

&lt;p&gt;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:&lt;p&gt;

&lt;p&gt;&lt;img src=&quot;http://people.skolelinux.org/pere/blog/images/2017-10-25-verk-i-det-fri-filmer.png&quot;&gt;&lt;/p&gt;

&lt;p&gt;I expect the relative distribution of the remaining 3000 movies to
be similar.&lt;/p&gt;

&lt;p&gt;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 &quot;External
links&quot; heading on the Wikipedia article for the movie:&lt;/p&gt;

&lt;p&gt;&lt;pre&gt;
* {{Internet Archive film|id=FightingLady}}
* {{IMDb title|id=0036823|title=The Fighting Lady}}
&lt;/pre&gt;&lt;/p&gt;

&lt;p&gt;Please verify the links on the final page, to make sure you did not
introduce a typo.&lt;/p&gt;

&lt;p&gt;Here is the complete list, if you want to correct the 171
identified Wikipedia entries with broken links to The Internet
Archive: &lt;a href=&quot;http://www.wikidata.org/entity/Q1140317&quot;&gt;Q1140317&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q458656&quot;&gt;Q458656&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q458656&quot;&gt;Q458656&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q470560&quot;&gt;Q470560&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q743340&quot;&gt;Q743340&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q822580&quot;&gt;Q822580&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q480696&quot;&gt;Q480696&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q128761&quot;&gt;Q128761&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1307059&quot;&gt;Q1307059&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1335091&quot;&gt;Q1335091&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1537166&quot;&gt;Q1537166&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1438334&quot;&gt;Q1438334&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1479751&quot;&gt;Q1479751&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1497200&quot;&gt;Q1497200&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1498122&quot;&gt;Q1498122&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q865973&quot;&gt;Q865973&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q834269&quot;&gt;Q834269&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q841781&quot;&gt;Q841781&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q841781&quot;&gt;Q841781&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1548193&quot;&gt;Q1548193&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q499031&quot;&gt;Q499031&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1564769&quot;&gt;Q1564769&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1585239&quot;&gt;Q1585239&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1585569&quot;&gt;Q1585569&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1624236&quot;&gt;Q1624236&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4796595&quot;&gt;Q4796595&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4853469&quot;&gt;Q4853469&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4873046&quot;&gt;Q4873046&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q915016&quot;&gt;Q915016&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4660396&quot;&gt;Q4660396&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4677708&quot;&gt;Q4677708&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4738449&quot;&gt;Q4738449&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4756096&quot;&gt;Q4756096&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4766785&quot;&gt;Q4766785&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q880357&quot;&gt;Q880357&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q882066&quot;&gt;Q882066&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q882066&quot;&gt;Q882066&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q204191&quot;&gt;Q204191&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q204191&quot;&gt;Q204191&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1194170&quot;&gt;Q1194170&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q940014&quot;&gt;Q940014&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q946863&quot;&gt;Q946863&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q172837&quot;&gt;Q172837&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q573077&quot;&gt;Q573077&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1219005&quot;&gt;Q1219005&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1219599&quot;&gt;Q1219599&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1643798&quot;&gt;Q1643798&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1656352&quot;&gt;Q1656352&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1659549&quot;&gt;Q1659549&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1660007&quot;&gt;Q1660007&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1698154&quot;&gt;Q1698154&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1737980&quot;&gt;Q1737980&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1877284&quot;&gt;Q1877284&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1199354&quot;&gt;Q1199354&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1199354&quot;&gt;Q1199354&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1199451&quot;&gt;Q1199451&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1211871&quot;&gt;Q1211871&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1212179&quot;&gt;Q1212179&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1238382&quot;&gt;Q1238382&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q4906454&quot;&gt;Q4906454&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q320219&quot;&gt;Q320219&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1148649&quot;&gt;Q1148649&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q645094&quot;&gt;Q645094&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q5050350&quot;&gt;Q5050350&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q5166548&quot;&gt;Q5166548&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q2677926&quot;&gt;Q2677926&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q2698139&quot;&gt;Q2698139&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q2707305&quot;&gt;Q2707305&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q2740725&quot;&gt;Q2740725&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q2024780&quot;&gt;Q2024780&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q2117418&quot;&gt;Q2117418&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q2138984&quot;&gt;Q2138984&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1127992&quot;&gt;Q1127992&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1058087&quot;&gt;Q1058087&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1070484&quot;&gt;Q1070484&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1080080&quot;&gt;Q1080080&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1090813&quot;&gt;Q1090813&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1251918&quot;&gt;Q1251918&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1254110&quot;&gt;Q1254110&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1257070&quot;&gt;Q1257070&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1257079&quot;&gt;Q1257079&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1197410&quot;&gt;Q1197410&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1198423&quot;&gt;Q1198423&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q706951&quot;&gt;Q706951&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q723239&quot;&gt;Q723239&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q2079261&quot;&gt;Q2079261&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q1171364&quot;&gt;Q1171364&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q617858&quot;&gt;Q617858&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q5166611&quot;&gt;Q5166611&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q5166611&quot;&gt;Q5166611&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q324513&quot;&gt;Q324513&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q374172&quot;&gt;Q374172&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q7533269&quot;&gt;Q7533269&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q970386&quot;&gt;Q970386&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q976849&quot;&gt;Q976849&lt;/a&gt;, 
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&lt;a href=&quot;http://www.wikidata.org/entity/Q18218448&quot;&gt;Q18218448&lt;/a&gt;, 
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&lt;a href=&quot;http://www.wikidata.org/entity/Q7239952&quot;&gt;Q7239952&lt;/a&gt;, 
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&lt;a href=&quot;http://www.wikidata.org/entity/Q7783674&quot;&gt;Q7783674&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q7783704&quot;&gt;Q7783704&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q7857590&quot;&gt;Q7857590&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q3372526&quot;&gt;Q3372526&lt;/a&gt;, 
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&lt;a href=&quot;http://www.wikidata.org/entity/Q3372816&quot;&gt;Q3372816&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q3372909&quot;&gt;Q3372909&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q7959649&quot;&gt;Q7959649&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q7977485&quot;&gt;Q7977485&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q7992684&quot;&gt;Q7992684&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q3817966&quot;&gt;Q3817966&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q3821852&quot;&gt;Q3821852&lt;/a&gt;, 
&lt;a href=&quot;http://www.wikidata.org/entity/Q3420907&quot;&gt;Q3420907&lt;/a&gt;, 
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</description>
        </item>
        
        <item>
                <title>A one-way wall on the border?</title>
                <link>http://people.skolelinux.org/pere/blog/A_one_way_wall_on_the_border_.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/A_one_way_wall_on_the_border_.html</guid>
                <pubDate>Sat, 14 Oct 2017 22:10:00 +0200</pubDate>
                <description>&lt;p&gt;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
&lt;a href=&quot;http://www.history.com/news/10-things-you-may-not-know-about-the-berlin-wall&quot;&gt;the
propaganda twist from the East Germany government&lt;/a&gt; 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.&lt;/p&gt;

&lt;p&gt;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?&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Generating 3D prints in Debian using Cura and Slic3r(-prusa)</title>
                <link>http://people.skolelinux.org/pere/blog/Generating_3D_prints_in_Debian_using_Cura_and_Slic3r__prusa_.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Generating_3D_prints_in_Debian_using_Cura_and_Slic3r__prusa_.html</guid>
                <pubDate>Mon, 9 Oct 2017 10:50:00 +0200</pubDate>
                <description>&lt;p&gt;At my nearby maker space,
&lt;a href=&quot;http://sonen.ifi.uio.no/&quot;&gt;Sonen&lt;/a&gt;, 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,
&lt;a href=&quot;https://github.com/Ultimaker/Cura&quot;&gt;Cura&lt;/a&gt;, 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
&lt;a href=&quot;https://bugs.debian.org/706656&quot;&gt;a request for adding into
Debian&lt;/a&gt; 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.&lt;/p&gt;

&lt;p&gt;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
&lt;a href=&quot;https://qa.debian.org/developer.php?email=3dprinter-general%40lists.alioth.debian.org&quot;&gt;the
status page for the 3D printer team&lt;/a&gt;.&lt;/p&gt;

&lt;p&gt;The uploaded packages are a bit behind upstream, and was uploaded
now to get slots in &lt;a href=&quot;https://ftp-master.debian.org/new.html&quot;&gt;the NEW
queue&lt;/a&gt; while we work up updating the packages to the latest
upstream version.&lt;/p&gt;

&lt;p&gt;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 &quot;slicers&quot; and want something already available in
Debian, check out
&lt;a href=&quot;https://tracker.debian.org/pkg/slic3r&quot;&gt;slic3r&lt;/a&gt; and
&lt;a href=&quot;https://tracker.debian.org/pkg/slic3r-prusa&quot;&gt;slic3r-prusa&lt;/a&gt;.
The latter is a fork of the former.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Mangler du en skrue, eller har du en skrue løs?</title>
                <link>http://people.skolelinux.org/pere/blog/Mangler_du_en_skrue__eller_har_du_en_skrue_l_s_.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Mangler_du_en_skrue__eller_har_du_en_skrue_l_s_.html</guid>
                <pubDate>Wed, 4 Oct 2017 09:40:00 +0200</pubDate>
                <description>Når jeg holder på med ulike prosjekter, så trenger jeg stadig ulike
skruer.  Det siste prosjektet jeg holder på med er å lage
&lt;a href=&quot;https://www.thingiverse.com/thing:676916&quot;&gt;en boks til en
HDMI-touch-skjerm&lt;/a&gt; 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.
&lt;a href=&quot;http://www.zachskruer.no/&quot;&gt;Zachariassen Jernvare AS&lt;/a&gt; i
&lt;a href=&quot;http://www.openstreetmap.org/?mlat=59.93421&amp;mlon=10.76795#map=19/59.93421/10.76795&quot;&gt;Hegermannsgate
23A på Torshov&lt;/a&gt; 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. :)&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Visualizing GSM radio chatter using gr-gsm and Hopglass</title>
                <link>http://people.skolelinux.org/pere/blog/Visualizing_GSM_radio_chatter_using_gr_gsm_and_Hopglass.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Visualizing_GSM_radio_chatter_using_gr_gsm_and_Hopglass.html</guid>
                <pubDate>Fri, 29 Sep 2017 10:30:00 +0200</pubDate>
                <description>&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;I am very happy to report that we managed to get something
visualizing this information up and running for
&lt;a href=&quot;http://norwaymakers.org/osf17&quot;&gt;Oslo Skaperfestival 2017&lt;/a&gt;
(Oslo Makers Festival) taking place today and tomorrow at Deichmanske
library.  The solution is based on the
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Easier_recipe_to_observe_the_cell_phones_around_you.html&quot;&gt;simple
recipe for listening to GSM chatter&lt;/a&gt; I posted a few days ago, and
will show up at the stand of &lt;a href=&quot;http://sonen.ifi.uio.no/&quot;&gt;Åpen
Sone from the Computer Science department of the University of
Oslo&lt;/a&gt;.  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.&lt;/p&gt;

&lt;p&gt;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
&lt;a href=&quot;https://github.com/marlow925/hopglass&quot;&gt;English version of
Hopglass&lt;/a&gt;.  A fairly powerfull machine is needed as the
grgsm_livemon_headless processes from
&lt;a href=&quot;https://tracker.debian.org/pkg/gr-gsm&quot;&gt;gr-gsm&lt;/a&gt; converting
the radio signal to data packages is quite CPU intensive.&lt;/p&gt;
                                        
&lt;p&gt;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
&lt;a href=&quot;https://github.com/petterreinholdtsen/IMSI-catcher/tree/meshviewer-output&quot;&gt;patches
in my meshviewer-output branch&lt;/a&gt;.  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
&lt;a href=&quot;https://github.com/Oros42/IMSI-catcher/issues/14&quot;&gt;the github
issue for the topic&lt;/a&gt;.

&lt;p&gt;If this sound interesting, visit the stand at the festival!&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Easier recipe to observe the cell phones around you</title>
                <link>http://people.skolelinux.org/pere/blog/Easier_recipe_to_observe_the_cell_phones_around_you.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Easier_recipe_to_observe_the_cell_phones_around_you.html</guid>
                <pubDate>Sun, 24 Sep 2017 08:30:00 +0200</pubDate>
                <description>&lt;p&gt;A little more than a month ago I wrote
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Simpler_recipe_on_how_to_make_a_simple__7_IMSI_Catcher_using_Debian.html&quot;&gt;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&lt;/a&gt;, 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.&lt;/p&gt;

&lt;p&gt;The &lt;a href=&quot;https://tracker.debian.org/pkg/gr-gsm&quot;&gt;gr-gsm&lt;/a&gt;
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.&lt;/p&gt;

&lt;p&gt;Here is an updated recipe, using packages built by Debian and a git
clone of two python scripts:&lt;/p&gt;

&lt;ol&gt;

&lt;li&gt;Start with a Debian machine running the Buster version (aka
  testing).&lt;/li&gt;

&lt;li&gt;Run &#39;&lt;tt&gt;apt install gr-gsm python-numpy python-scipy
  python-scapy&lt;/tt&gt;&#39; as root to install required packages.&lt;/li&gt;

&lt;li&gt;Fetch the code decoding GSM packages using &#39;&lt;tt&gt;git clone
  github.com/Oros42/IMSI-catcher.git&lt;/tt&gt;&#39;.&lt;/li&gt;

&lt;li&gt;Insert USB software defined radio supported by GNU Radio.&lt;/li&gt;

&lt;li&gt;Enter the IMSI-catcher directory and run &#39;&lt;tt&gt;python
  scan-and-livemon&lt;/tt&gt;&#39; to locate the frequency of nearby base
  stations and start listening for GSM packages on one of them.&lt;/li&gt;

&lt;li&gt;Enter the IMSI-catcher directory and run &#39;&lt;tt&gt;python
  simple_IMSI-catcher.py&lt;/tt&gt;&#39; to display the collected information.&lt;/li&gt;

&lt;/ol&gt;

&lt;p&gt;Note, due to a bug somewhere the scan-and-livemon program (actually
&lt;a href=&quot;https://github.com/ptrkrysik/gr-gsm/issues/336&quot;&gt;its underlying
program grgsm_scanner&lt;/a&gt;) do not work with the HackRF radio.  It does
work with RTL 8232 and other similar USB radio receivers you can get
very cheaply
(&lt;a href=&quot;https://www.ebay.com/sch/items/?_nkw=rtl+2832&quot;&gt;for example
from ebay&lt;/a&gt;), so for now the solution is to scan using the RTL radio
and only use HackRF for fetching GSM data.&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;I&#39;ve tried to run the scanner on a
&lt;a href=&quot;https://wiki.debian.org/RaspberryPi&quot;&gt;Raspberry Pi 2 and 3
running Debian Buster&lt;/a&gt;, but the grgsm_livemon_headless process seem
to be too CPU intensive to keep up.  When GNU Radio print &#39;O&#39; 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 &#39;O&#39;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().&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Datalagringsdirektivet kaster skygger over Høyre og Arbeiderpartiet</title>
                <link>http://people.skolelinux.org/pere/blog/Datalagringsdirektivet_kaster_skygger_over_H_yre_og_Arbeiderpartiet.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Datalagringsdirektivet_kaster_skygger_over_H_yre_og_Arbeiderpartiet.html</guid>
                <pubDate>Thu, 7 Sep 2017 21:35:00 +0200</pubDate>
                <description>&lt;p&gt;For noen dager siden publiserte Jon Wessel-Aas en bloggpost om
«&lt;a href=&quot;http://www.uhuru.biz/?p=1821&quot;&gt;Konklusjonen om datalagring som
EU-kommisjonen ikke ville at vi skulle få se&lt;/a&gt;».  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.&lt;/p&gt;

&lt;p&gt;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
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Datalagringsdirektivet_gj_r_at_Oslo_H_yre_og_Arbeiderparti_ikke_f_r_min_stemme_i__r.html&quot;&gt;denne
gangen heller&lt;/a&gt;.  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.&lt;/p&gt;

&lt;p&gt;Det er tydelig fra diskusjonen rundt grenseløs digital overvåkning
(eller &quot;Digital Grenseforsvar&quot; 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
&lt;a href=&quot;https://data.holderdeord.no/votes/1301946411e&quot;&gt;de som stemte
for Datalagringsdirektivet i Stortinget&lt;/a&gt; (64 fra Arbeiderpartiet,
25 fra Høyre) er fortsatt aktive og argumenterer fortsatt for å radere
vekk mer av innbyggernes privatsfære.&lt;/p&gt;

&lt;p&gt;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.
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/How_to_talk_with_your_loved_ones_in_private.html&quot;&gt;Det
er mange muligheter&lt;/a&gt;.  Selv har jeg litt sans for
&lt;a href=&quot;https://ring.cx/&quot;&gt;Ring&lt;/a&gt;, 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
&lt;a href=&quot;https://tracker.debian.org/pkg/ring&quot;&gt;Debian&lt;/a&gt; og
&lt;a href=&quot;https://launchpad.net/ubuntu/+source/ring&quot;&gt;Ubuntu&lt;/a&gt;, og det
finnes pakker for Android, MacOSX og Windows.  Foreløpig er det få
brukere med Ring, slik at jeg også bruker
&lt;a href=&quot;https://signal.org/&quot;&gt;Signal&lt;/a&gt; som nettleserutvidelse.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Simpler recipe on how to make a simple $7 IMSI Catcher using Debian</title>
                <link>http://people.skolelinux.org/pere/blog/Simpler_recipe_on_how_to_make_a_simple__7_IMSI_Catcher_using_Debian.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Simpler_recipe_on_how_to_make_a_simple__7_IMSI_Catcher_using_Debian.html</guid>
                <pubDate>Wed, 9 Aug 2017 23:59:00 +0200</pubDate>
                <description>&lt;p&gt;On friday, I came across an interesting article in the Norwegian
web based ICT news magazine digi.no on
&lt;a href=&quot;https://www.digi.no/artikler/sikkerhetsforsker-lagde-enkel-imsi-catcher-for-60-kroner-na-kan-mobiler-kartlegges-av-alle/398588&quot;&gt;how
to collect the IMSI numbers of nearby cell phones&lt;/a&gt; using the cheap
DVB-T software defined radios.  The article refered to instructions
and &lt;a href=&quot;https://www.youtube.com/watch?v=UjwgNd_as30&quot;&gt;a recipe by
Keld Norman on Youtube on how to make a simple $7 IMSI Catcher&lt;/a&gt;, and I decided to test them out.&lt;/p&gt;

&lt;p&gt;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-&gt;pip-&gt;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.&lt;/p&gt;

&lt;p&gt;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&#39;ve been testing the
collector for a few days now.&lt;/p&gt;

&lt;p&gt;The updated and simpler recipe is thus to&lt;/p&gt;

&lt;ol&gt;

&lt;li&gt;start with a Debian machine running Stretch or newer,&lt;/li&gt;

&lt;li&gt;build and install the gr-gsm package available from
&lt;a href=&quot;http://ppa.launchpad.net/ptrkrysik/gr-gsm/ubuntu/pool/main/g/gr-gsm/&quot;&gt;http://ppa.launchpad.net/ptrkrysik/gr-gsm/ubuntu/pool/main/g/gr-gsm/&lt;/a&gt;,&lt;/li&gt;

&lt;li&gt;clone the git repostory from &lt;a href=&quot;https://github.com/Oros42/IMSI-catcher&quot;&gt;https://github.com/Oros42/IMSI-catcher&lt;/a&gt;,&lt;/li&gt;

&lt;li&gt;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).&lt;/li&gt;

&lt;li&gt;go into the IMSI-catcher directory and run &#39;sudo python simple_IMSI-catcher.py&#39; to extract the IMSI numbers.&lt;/li&gt;

&lt;/ol&gt;

&lt;p&gt;To make it even easier in the future to get this sniffer up and
running, I decided to package
&lt;a href=&quot;https://github.com/ptrkrysik/gr-gsm/&quot;&gt;the gr-gsm project&lt;/a&gt;
for Debian (&lt;a href=&quot;https://bugs.debian.org/871055&quot;&gt;WNPP
#871055&lt;/a&gt;), 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.&lt;/p&gt;

&lt;p&gt;I doubt this &quot;IMSI cacher&quot; is anywhere near as powerfull as
commercial tools like
&lt;a href=&quot;https://www.thespyphone.com/portable-imsi-imei-catcher/&quot;&gt;The
Spy Phone Portable IMSI / IMEI Catcher&lt;/a&gt; or the
&lt;a href=&quot;https://en.wikipedia.org/wiki/Stingray_phone_tracker&quot;&gt;Harris
Stingray&lt;/a&gt;, 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...&lt;/p&gt;

&lt;p&gt;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?&lt;/p&gt;
</description>
        </item>
        
        </channel>
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