- <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><p>On friday, I came across an interesting article in the Norwegian
-web based ICT news magazine digi.no on
-<a href="https://www.digi.no/artikler/sikkerhetsforsker-lagde-enkel-imsi-catcher-for-60-kroner-na-kan-mobiler-kartlegges-av-alle/398588">how
-to collect the IMSI numbers of nearby cell phones</a> using the cheap
-DVB-T software defined radios. The article refered to instructions
-and <a href="https://www.youtube.com/watch?v=UjwgNd_as30">a recipe by
-Keld Norman on Youtube on how to make a simple $7 IMSI Catcher</a>, and I decided to test them out.</p>
-
-<p>The instructions said to use Ubuntu, install pip using apt (to
-bypass apt), use pip to install pybombs (to bypass both apt and pip),
-and the ask pybombs to fetch and build everything you need from
-scratch. I wanted to see if I could do the same on the most recent
-Debian packages, but this did not work because pybombs tried to build
-stuff that no longer build with the most recent openssl library or
-some other version skew problem. While trying to get this recipe
-working, I learned that the apt->pip->pybombs route was a long detour,
-and the only piece of software dependency missing in Debian was the
-gr-gsm package. I also found out that the lead upstream developer of
-gr-gsm (the name stand for GNU Radio GSM) project already had a set of
-Debian packages provided in an Ubuntu PPA repository. All I needed to
-do was to dget the Debian source package and built it.</p>
-
-<p>The IMSI collector is a python script listening for packages on the
-loopback network device and printing to the terminal some specific GSM
-packages with IMSI numbers in them. The code is fairly short and easy
-to understand. The reason this work is because gr-gsm include a tool
-to read GSM data from a software defined radio like a DVB-T USB stick
-and other software defined radios, decode them and inject them into a
-network device on your Linux machine (using the loopback device by
-default). This proved to work just fine, and I've been testing the
-collector for a few days now.</p>
-
-<p>The updated and simpler recipe is thus to</p>
-
-<ol>
-
-<li>start with a Debian machine running Stretch or newer,</li>
-
-<li>build and install the gr-gsm package available from
-<a href="http://ppa.launchpad.net/ptrkrysik/gr-gsm/ubuntu/pool/main/g/gr-gsm/">http://ppa.launchpad.net/ptrkrysik/gr-gsm/ubuntu/pool/main/g/gr-gsm/</a>,</li>
-
-<li>clone the git repostory from <a href="https://github.com/Oros42/IMSI-catcher">https://github.com/Oros42/IMSI-catcher</a>,</li>
-
-<li>run grgsm_livemon and adjust the frequency until the terminal
-where it was started is filled with a stream of text (meaning you
-found a GSM station).</li>
-
-<li>go into the IMSI-catcher directory and run 'sudo python simple_IMSI-catcher.py' to extract the IMSI numbers.</li>
-
-</ol>
-
-<p>To make it even easier in the future to get this sniffer up and
-running, I decided to package
-<a href="https://github.com/ptrkrysik/gr-gsm/">the gr-gsm project</a>
-for Debian (<a href="https://bugs.debian.org/871055">WNPP
-#871055</a>), and the package was uploaded into the NEW queue today.
-Luckily the gnuradio maintainer has promised to help me, as I do not
-know much about gnuradio stuff yet.</p>
-
-<p>I doubt this "IMSI cacher" is anywhere near as powerfull as
-commercial tools like
-<a href="https://www.thespyphone.com/portable-imsi-imei-catcher/">The
-Spy Phone Portable IMSI / IMEI Catcher</a> or the
-<a href="https://en.wikipedia.org/wiki/Stingray_phone_tracker">Harris
-Stingray</a>, but I hope the existance of cheap alternatives can make
-more people realise how their whereabouts when carrying a cell phone
-is easily tracked. Seeing the data flow on the screen, realizing that
-I live close to a police station and knowing that the police is also
-wearing cell phones, I wonder how hard it would be for criminals to
-track the position of the police officers to discover when there are
-police near by, or for foreign military forces to track the location
-of the Norwegian military forces, or for anyone to track the location
-of government officials...</p>
-
-<p>It is worth noting that the data reported by the IMSI-catcher
-script mentioned above is only a fraction of the data broadcasted on
-the GSM network. It will only collect one frequency at the time,
-while a typical phone will be using several frequencies, and not all
-phones will be using the frequencies tracked by the grgsm_livemod
-program. Also, there is a lot of radio chatter being ignored by the
-simple_IMSI-catcher script, which would be collected by extending the
-parser code. I wonder if gr-gsm can be set up to listen to more than
-one frequency?</p>
+ <title>Streaming the Linux desktop to Kodi using VLC and RTSP</title>
+ <link>http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html</link>
+ <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html</guid>
+ <pubDate>Thu, 12 Jul 2018 02:00:00 +0200</pubDate>
+ <description><p>PS: See
+<ahref="http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html">the
+followup post</a> for a even better approach.</p>
+
+<p>A while back, I was asked by a friend how to stream the desktop to
+my projector connected to Kodi. I sadly had to admit that I had no
+idea, as it was a task I never had tried. Since then, I have been
+looking for a way to do so, preferable without much extra software to
+install on either side. Today I found a way that seem to kind of
+work. Not great, but it is a start.</p>
+
+<p>I had a look at several approaches, for example
+<a href="https://github.com/mfoetsch/dlna_live_streaming">using uPnP
+DLNA as described in 2011</a>, but it required a uPnP server, fuse and
+local storage enough to store the stream locally. This is not going
+to work well for me, lacking enough free space, and it would
+impossible for my friend to get working.</p>
+
+<p>Next, it occurred to me that perhaps I could use VLC to create a
+video stream that Kodi could play. Preferably using
+broadcast/multicast, to avoid having to change any setup on the Kodi
+side when starting such stream. Unfortunately, the only recipe I
+could find using multicast used the rtp protocol, and this protocol
+seem to not be supported by Kodi.</p>
+
+<p>On the other hand, the rtsp protocol is working! Unfortunately I
+have to specify the IP address of the streaming machine in both the
+sending command and the file on the Kodi server. But it is showing my
+desktop, and thus allow us to have a shared look on the big screen at
+the programs I work on.</p>
+
+<p>I did not spend much time investigating codeces. I combined the
+rtp and rtsp recipes from
+<a href="https://wiki.videolan.org/Documentation:Streaming_HowTo/Command_Line_Examples/">the
+VLC Streaming HowTo/Command Line Examples</a>, and was able to get
+this working on the desktop/streaming end.</p>
+
+<blockquote><pre>
+vlc screen:// --sout \
+ '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{dst=projector.local,port=1234,sdp=rtsp://192.168.11.4:8080/test.sdp}'
+</pre></blockquote>
+
+<p>I ssh-ed into my Kodi box and created a file like this with the
+same IP address:</p>
+
+<blockquote><pre>
+echo rtsp://192.168.11.4:8080/test.sdp \
+ > /storage/videos/screenstream.m3u
+</pre></blockquote>
+
+<p>Note the 192.168.11.4 IP address is my desktops IP address. As far
+as I can tell the IP must be hardcoded for this to work. In other
+words, if someone elses machine is going to do the steaming, you have
+to update screenstream.m3u on the Kodi machine and adjust the vlc
+recipe. To get started, locate the file in Kodi and select the m3u
+file while the VLC stream is running. The desktop then show up in my
+big screen. :)</p>
+
+<p>When using the same technique to stream a video file with audio,
+the audio quality is really bad. No idea if the problem is package
+loss or bad parameters for the transcode. I do not know VLC nor Kodi
+enough to tell.</p>
+
+<p><strong>Update 2018-07-12</strong>: Johannes Schauer send me a few
+succestions and reminded me about an important step. The "screen:"
+input source is only available once the vlc-plugin-access-extra
+package is installed on Debian. Without it, you will see this error
+message: "VLC is unable to open the MRL 'screen://'. Check the log
+for details." He further found that it is possible to drop some parts
+of the VLC command line to reduce the amount of hardcoded information.
+It is also useful to consider using cvlc to avoid having the VLC
+window in the desktop view. In sum, this give us this command line on
+the source end
+
+<blockquote><pre>
+cvlc screen:// --sout \
+ '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{sdp=rtsp://:8080/}'
+</pre></blockquote>
+
+<p>and this on the Kodi end<p>
+
+<blockquote><pre>
+echo rtsp://192.168.11.4:8080/ \
+ > /storage/videos/screenstream.m3u
+</pre></blockquote>
+
+<p>Still bad image quality, though. But I did discover that streaming
+a DVD using dvdsimple:///dev/dvd as the source had excellent video and
+audio quality, so I guess the issue is in the input or transcoding
+parts, not the rtsp part. I've tried to change the vb and ab
+parameters to use more bandwidth, but it did not make a
+difference.</p>
+
+<p>I further received a suggestion from Einar Haraldseid to try using
+gstreamer instead of VLC, and this proved to work great! He also
+provided me with the trick to get Kodi to use a multicast stream as
+its source. By using this monstrous oneliner, I can stream my desktop
+with good video quality in reasonable framerate to the 239.255.0.1
+multicast address on port 1234:
+
+<blockquote><pre>
+gst-launch-1.0 ximagesrc use-damage=0 ! video/x-raw,framerate=30/1 ! \
+ videoconvert ! queue2 ! \
+ x264enc bitrate=8000 speed-preset=superfast tune=zerolatency qp-min=30 \
+ key-int-max=15 bframes=2 ! video/x-h264,profile=high ! queue2 ! \
+ mpegtsmux alignment=7 name=mux ! rndbuffersize max=1316 min=1316 ! \
+ udpsink host=239.255.0.1 port=1234 ttl-mc=1 auto-multicast=1 sync=0 \
+ pulsesrc device=$(pactl list | grep -A2 'Source #' | \
+ grep 'Name: .*\.monitor$' | cut -d" " -f2|head -1) ! \
+ audioconvert ! queue2 ! avenc_aac ! queue2 ! mux.
+</pre></blockquote>
+
+<p>and this on the Kodi end<p>
+
+<blockquote><pre>
+echo udp://@239.255.0.1:1234 \
+ > /storage/videos/screenstream.m3u
+</pre></blockquote>
+
+<p>Note the trick to pick a valid pulseaudio source. It might not
+pick the one you need. This approach will of course lead to trouble
+if more than one source uses the same multicast port and address.
+Note the ttl-mc=1 setting, which limit the multicast packages to the
+local network. If the value is increased, your screen will be
+broadcasted further, one network "hop" for each increase (read up on
+multicast to learn more. :)!</p>
+
+<p>Having cracked how to get Kodi to receive multicast streams, I
+could use this VLC command to stream to the same multicast address.
+The image quality is way better than the rtsp approach, but gstreamer
+seem to be doing a better job.</p>
+
+<blockquote><pre>
+cvlc screen:// --sout '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{mux=ts,dst=239.255.0.1,port=1234,sdp=sap}'
+</pre></blockquote>
+
+<p>As usual, if you use Bitcoin and want to show your support of my
+activities, please send Bitcoin donations to my address
+<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
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