Notes on Bluetooth on Linux internals

Introduction These are notes I made while trying to make my Sony WH-CH510 bluetooth headphones work properly with my Linux Mint 19 machine. It’s evident that an upgrade of the whole OS would have fixed the problem, but I have my opinion on upgrades. The problem: It takes a long time for the headphones to [...]

udev, the “authorized” attribute and other failed attempts to ban a bogus USB keyboard

Introduction This is a spin-off post about failing attempts to fix the problem with a webcam’s keyboard buttons. Namely, that the a shaky physical connections caused the USB device to go on and off the bus rapidly, and consequently crash X windows. The background story is in this post. There is really nothing to learn [...]

Using git send-email with Gmail + OAUTH2, but without subscribing to cloud services

Introduction There is a widespread belief, that in order to use git send-email with Gmail, there’s a need to subscribe to Google Cloud services and obtain some credentials. Or that a two-factor authentication (2fa) is required. This is not the case, however. If Thunderbird can manage to fetch and send emails through Google’s mail servers [...]

Linux + webcam: Poor man’s DIY surveillance camera

Introduction Due to an incident that is beyond the scope of this blog, I wanted to put a 24/7 camera that watched a certain something, just in case that incident repeated itself. Having a laptop that I barely use, and a cheap e-bay web camera, I thought I set up something and let ffmpeg do [...]

Blocking bots by their IP addresses, the DIY version

Introduction I had some really annoying bots on one of my websites. Of the sort that make a million requests (like really, a million) per month, identifying themselves as a browser. So IP blocking it is. I went for a minimalistic DIY approach. There are plenty of tools out there, but my experience with things [...]

Thunderbird: Upgrade notes

Introduction These are my notes as I upgraded Thunderbird from version 3.0.7 (released September 2010) to 91.10.0 on Linux Mint 19. That’s more than a ten year’s gap, which says something about what I think about upgrading software (which was somewhat justified, given the rubbish issues that arose, as detailed below). What eventually forced me [...]

Run Firefox over X11 over SSH / VNC on a cheap virtual machine

To run over SSH: Not This is how to run a Firefox browser on a cheap VPS machine (e.g. a Google Cloud VM Instance) with an X-server connection. It’s actually not a good idea, because it’s extremely slow. The correct way is to set up a VNC server, because the X server connection exchanges information [...]

Using firejail to throttle network bandwidth for wget and such

Introduction Occasionally, I download / upload huge files, and it kills my internet connection for plain browsing. I don’t want to halt the download or suspend it, but merely calm it down a bit, temporarily, for doing other stuff. And then let it hog as much as it want again. There are many ways to [...]

Octave: Creating images from plots for web page

This should have been a trivial task, but it turned out quite difficult. So these are my notes for the next time. Octave 4.2.2 under Linux Mint 19, using qt5ct plugin with GNU plot (or else I get blank plots). So this is the small function I wrote for creating a plot and a thumbnail: [...]

When dovecot silently stops to deliver mails

After a few days being happy with not getting spam, I started to suspect that something is completely wrong with receiving mail. As I’m using fetchmail to get mail from my own server running dovecot v2.2.13, I’m used to getting notifications when fetchmail is unhappy. But there was no such. Checking up the server’s logs, [...]