About an year ago I was contacted by someone who tried to use my script on MP4 files generated by their camera, only to get garbage data out. It appeared that the camera was obfuscating the coordinates stored in MP4 (the speed and heading was recorded correctly). It was not a bug because provided player was decoding them correctly.
As of writing this I already had complete solution (as far as getting tracking data is concerned), a multi-process TCP server with a mysql database back-end. The server code itself is not pretty thus I am cautious about sharing it at this stage (I will “open-source” it once I cleaned it up).
One caveat: my solution does not support batch mode (where the payload contain multiple concatenated location and other packets).
The assumption is that the reader is somewhat familiar with python and sockets.
Below I will describe how I got rid of ads on my android phone without rooting it.
It is very easy to get rid of ads on an android smart phone if you have root access. Unfortunately pesky manufacturers insist on declining warranty if the phone is rooted.
I will probably one day test this is in small claims court for a cheaper phone. I digress…
Some linux box/container/VM. In this post I used Ubuntu 16.04 LTS
Public IP on the box from above
Some linux/cli/unix experience
How does it work?
Smart phone connects to the Linux box via OpenVPN
Linux box is running Pi-hole which acts as a selective DNS server
I had a need for a simple IMAP to IMAP sync tool, yet the only useful things I could find were offlineimap and imapsync.
The offlineimap is too complex and does not exactly do what I want; while the latter went commercial and not is not a clean install (requires messing with CPAN/perl libraries).
It logs in into both IMAP servers and basically copies (with optional source deletion) the messages across. It also avoids duplication by checking Message-ID header. It should be stable enough to “daemon”-ify.
Here is a systemd unit for it (if one wants it to run all the time):
No, I am not suggesting to hammer the knock sensor ;).
Recently I was diagnosing a very intermittent error code 52 (knock sensor open/closed circuit) on a 4AFE powered Toyota Corolla.
I needed a way to test the actual functionality of the knock sensor in a garage.
From my understanding a typical knock sensor is pretty much a condenser microphone. So measuring resistance of it pretty much meaningless beyond finding a completely stuffed one. The repair manual suggest that the resistance of one should be above 1 MOhm, as it should be, as it is a capacitor.
One requirement for this kind of crude testing is having a multimeter that does capacitance testing in the nF range.
The particular knock sensor I was testing measured at about 6-7nF (temperature dependant) sensor alone, or ~7.5nF with the wiring.
The test is very simple, I have unplugged the sensor from the ECU, plugged one probe form the multimeter (set to Capacitance range) to the pin for the knock sensor on the ECU plug, and another on chassis/earth/ground. Then I knocked on a random bolt on the engine block and watch the measurment:
This resulted an increase of the capacitance for each knock (to over 8nF).
Another test that is not on the video, is basically using rattle gun on a bolt. This produced over 1.5nF increase.
I have also tested the sensor outside in a vice while heating it up with heat gun to 120 degrees C. The capacitance increased by ~2nF during heating. The sensor responding in similar way as above to light knocks on the vice anvil.
Alternative and more sophisticated way of testing is hooking up sensor to the microphone input on a cellphone/Laptop/PC but that would involve butchering a 3.5mm jack.