X-Git-Url: http://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/cb2bffc9f0c093d20f059990477781700cd1f6a8..aaf3a8d6ac3f87b3060fda22f11cb474d2e37af0:/blog/archive/2017/09/index.html diff --git a/blog/archive/2017/09/index.html b/blog/archive/2017/09/index.html index 8002bd42cd..8cfddb7e8a 100644 --- a/blog/archive/2017/09/index.html +++ b/blog/archive/2017/09/index.html @@ -21,6 +21,77 @@

Entries from September 2017.

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

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+ + + Tags: debian, english, personvern, surveillance. + + +
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Easier recipe to observe the cell phones around you @@ -71,7 +142,7 @@ clone of two python scripts:

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 do +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 @@ -180,6 +251,29 @@ brukere med Ring, slik at jeg også bruker

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