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Wireless Socket Sniffer/Remote Control

Sniff packets of the remote with your SDR and see what socket has been turned on/off. Also, you can control the wireless sockets.

The System

This is what a socket and the remote look like.
Socket and Remote

You can configure the address (aka. system-code) and the identifier (aka. unit-code) of your sockets using the DIP switches.
DIP switches of the socket

Don't forget to set the same address on the remote.
DIP switches of the remote

For controlling the sockets, the remote sends out a simple signal modulated using on-off-keying (ASK/OOK). The encoding is covered by this great blog post (German, but with helpful pictures).


  • A working installation of GnuRadio. This project was created with GNU Radio Companion 3.7.9 git-99-gaae64454. GNU Radio Companion 3.7.8 worked well too.
  • A Software Defined Radio (e.g. HackRF, rad1o, USRP, RTL-SDR, etc.) This project was tested with the rad1o SDR.
  • An antenna suitable for the 433 ISM band.

Configure the Software

Although the socket is labeled "433.92 MHz" I got the best results when setting the channel frequency to 433.85 MHz. You can set the channel frequency by editing the channel_freq variable in the GnuRadio flow graph (.grc files). Also you can switch the SDR source/sink (e.g. to UHD) and edit its gain values.

Don't forget to delete the A new version of these files will be generated which will include the changes made in the GnuRadio flow graph.

Sniffing Packets

You can sniff the commands of remote controls to see what socket with what address has been switched on/off.

$ cd rx
$ ./ -h
usage: [-h] [-g] [-l] [-e]

optional arguments:
  -h, --help           show this help message and exit
  -g, --grcoutput      Show the output of gnuradio/grcc.
  -l, --ignore-length  Show packets even if the length is not 25 bits.
  -e, --ignore-errors  Decode packets even if some bits make no sense.


$ cd rx
$ ./
[+] Create UDP server to receive gnuradio output.
[+] Launch gnuradio script to feed the UDP server.
[+] Wait 1 second for gnuradio to boot up.
[+] Start decoding.
[+] New Packet:
  Address: 01101
  Identifier: B
  State: ON
[+] Got keyboard interrupt.
[+] Terminate gnuradio.
[+] Close UDP server.
[+] Exit.

Controlling Sockets

You can control the socket using the script. Just specify the address, socket identifier and the state you want to put it into (on or off). Also, there is some kind of a brute force feature. Switch on/off all sockets within range of your SDR by a simple command. But remember: This will probably switch off the sockets of you neighbors too. And you don't what to switch off their aquarium infrastructure to let the poor fishes die, won't you?

$ cd tx
$ ./ -h
usage: [-h] [-g] [-r REPEAT] -a ADDRESS -i IDENTIFIER -s

optional arguments:
  -h, --help            show this help message and exit
  -g, --grcoutput       Show the output of gnuradio/grcc.
  -r REPEAT, --repeat REPEAT
                        Repeat every packet REPEAT times. Default is 3.
  -a ADDRESS, --address ADDRESS
                        Address string of sockets, e.g. 00101 or ALL.
  -i IDENTIFIER, --identifier IDENTIFIER
                        Socket identifier. A, B, C, D, E or ALL.
  -s STATE, --state STATE
                        Switch the power 'on' or 'off'.

Example (switch on socket B with address 01101):

$ cd tx
$ ./ -a 01101 -i b -s on
[+] Create FIFO file to communicate with gnuradio.
[+] Launch gnuradio script to send packages from the FIFO file.
[-] gnuradio script not found. Creating script from .grc file.
[+] Wait 1 second for gnuradio to boot up.
[+] Every packet will be repeated 3 times.
[+] Added packet to send queue: addr=01101, id=b, state=on.
[+] Sending packets... This will take about 0.149 seconds.
[+] Wait 1 second before terminating gnuradio.
[+] Terminate gnuradio.
[+] Remove FIFO file.
[+] Exit.


Control wireless sockets using an SDR




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