NodeMCU based PIR motion sensor supporting WiFi and MQTT
Mini tutorial on how to use the NodeMCU Amica and a cheap PIR sensor module to build a pretty simple motion sensor that supports reporting via MQTT messages.
Frama-C predicates
Really short primer on ACSL predicates for formal verification of ANSI C code with Frama-C.
Frama-C with wp-dynamic and function pointers
How to use Frama-C static analysis and proof assitant with ACSL annotations for function pointers in ANSI C.
How this site is built with Jekyll and Jenkins
A short summary on how this page is built using the Jekyll static website generator as well as a really simple Jenkins job that's triggered by a GitHub webhook.
Automatic Ethernet and WiFi failover on FreeBSD
Short introduction on how to use lagg(4) to perform automatic seamless switching from ethernet to WiFi (when they represent the same network on the same IP subnet) and back on FreeBSD.
Simple usage of Kerberos for SSH authentication on FreeBSD
A short primer on how to get started using Kerberos for authentication inside your network. This includes setup of an kerberos key distribution center (KDC) on an secure host as well as of the server machines against which one will authenticate as well as the required configuration on the clients.
Selenium with Chromium and Java on FreeBSD
This is a short description on how to get started using Selenium with chromedriver on FreeBSD with a Java application. This can be used to develop automatic test applications for web applications or simple bots that scrape content from webpages or automate actions on the web using a full browser capable of running JavaScript, running browser plugins, etc. (Update - In addition an implementation in Python has been added to show a short draft on how one can get started with Selenium in Python as well.)
Using Sonoff T4EU1C non-neutral switches with own firmware
A short review about the T4EU1C Sonoff Switch as well as an example how to flash Sonoff basic switches with custom firmware
Getting started with node-red for home/lab/process automation
A short tutorial on how to setup node red and configure the first flows to be used with sonoff basic switches and other data sources as well as XMPP/MQTT interfaces and some other ideas how one can use node red in various areas
Privacy - TOR, VPN, DOH, Encryption. What's effective and what does it provide?
Since I often hear confusion about the level or type of privacy when I talk with people about onion routing services like TOR, tunneling services like VPN, DNS encryption via DOH, using proxyservers, using alternate DNS services, using encryption and signature, etc. I've decided to write a short blog post about that different stuff and what it provides - and what not (in my personal opinion).
Simple ESP8266 blink example with NONOS SDK and custom Makefile
Example on how one can use the ESP8266 NONOS SDK to build applications using a custom Makefile (i.e. not using the nested Makefiles of espressifs SDK) to build one of the most simple microcontroller projects.
Manually compiling ESP8266 applications
A short description on what the ESP8266-NONOS-SDK really does (step by step) to build the firmware images that get uploaded to the microcontroller via esptool.
How to use Frama-C to proof correctness of AVR microcontroller code
This is a short article that shows how one can use Frama-C and the WP plugin to proof correctness or some properties of ANSI C code written for AVR microcontrollers.
Some respectable TOR hidden services
Because it's sometimes said TOR hidden services are only used by criminals this post lists a few more credible services and some reasons why one might use them.
Clone or pull all your github repos (possible as basis for a backup)
A short summary on how to use the GitHub API with access tokens to mirror all your GitHub repositories and keep them up to date.
x86 and x86-64 memory models
A really short *unfinished* introduction into the various memory models of the x86 architecture
Using an IPv6 tunnel broker
How to get an IPv6 network connection working if your ISP doesn't support IPv6 even today. Also includes a short description on how to do this on an connection using dynamic endpoint adresses.
Setting up the ESP32 and ESP8266 build environment
Short summary on how to setup the development environment for ESP8266 (Non-OS and RTOS) as well as ESP32 (RTOS) including a short shellscript that's capable of setting up the development environment.
OpenHantek on FreeBSD for USB oscilloscope
A really short description on how to build OpenHantek on FreeBSD and how to configure the system - and how to create a FreeBSD port.
Configuring ADSL PPTP connection (for example with Austrian DSL providers) on FreeBSD with mpd5
A short summary on how to configure mpd5 to authenticate against an external PPP provider for PPPoA usage (via PPTP). This is required for authentication with most Austrian (A)DSL providers when using their modems in single user mode.
Running Android Studio (or any other X11 application) on a remote machine via X11
A short rant on the incapability of Android Studio to be portable over various POSIX operating systems and a hackish solution on how to keep the feeling of a local application while running it remotely on a Linux machine.
Using piezo disks for automatic bed leveling on 3D printers
Description of an easy way of using piezo disks as touch sensors to perform bed leveling with 3D printers or other CNC machines. This blog entry describes the most basic possible way without much external circuits (only an ATtiny13A and two resistors are used)
GIT and SVN interoperability or moving from SVN to GIT without loosing history
How to use the GIT client to interoperate with a remote SVN server or how to migrate an SVN repository to GIT including it's full history.
What is Multifactor authentication (MFA) and how to use a Yubikey on FreeBSD for Web and PAM (Local, SSH, etc.) authentication
This article contains a short tutorial about multifactor authentication, various factors that may be used and a tutorial on how to use the Yubikey hardware token for web- and local as well as SSH (pam) authentication on FreeBSD.
How to use TOR as normal user
A short description how to use TOR as a normal user and what to be aware of when using TOR
How to use Frama-C to proof C code (short primer)
A short primer on how to use Frama-C to proof properties about C-code.
What are JSON web tokens any why would one want to use them?
Just a short description of what a JWT is, what it can do for one and how they are realized - and why one would want to use them to identify users in one's web application by using JWTs instead of session IDs.
Authenticating and signing using Austrias citizen card
A short summary on how to embed authentication and generally signing with the Austrian citizien card
Building an I2C controllable stepper driver board with DRV8825 breakout boards and ATMega328p
This is the description of a small carrier board for two DRV8825 breakout boards (or compatible) that are controlled by an AVR (ATMega328p) which runs a small (linear) motion processor that gets it's commands via I2C.
Using Git / Git Cheatsheet
A short cheat sheet on how to use the git version control system (most basic operations)
I2C communication between RaspberryPi and an AVR based I2C slave
This article explains how to use an AVR as I2C slave device (basically how to set registers for the TWI controller) and how to interface that to an RaspberryPi running FreeBSD
The Blogsphere - How pingbacks work
The blogsphere is a web of interconnected websites. As usual websites are linked like all pages in the WWW but on the other hand they provide an easy way of notifying each other of being referenced by a third party. Pingback is - besides trackbacks - the (XML-RPC based) technology used for that notification.
Where does complex impedance come from?
This post describes a simple derivation of the complex inpedance formulas well known from electronics.
Using cheap 28BYJ-48 stepper with ULM2003 drivers and AVR/Arduino
Short explanation on how to use the 28BYJ-48 geared stepper motor with the ULM2003 7-way Darlington transistor array.
Fast ballpark calculation of maximum speed for maximum car througput (using simple high-school physics and math)
Something most drivers don't want to hear - a basic pallpark calculation of the optimal maximum speed that offers the maximum car througput on streets.
Using AVRs GPIO pins with avr-gcc
How to use the GPIO pins on the AVR microcontrollers when using avr-gcc
Comparison of TAN mechanisms and alternatives
This blog post should provide a short overview of TAN alternatives and methods as well as their pitfalls and security
Wie DKIM und SPF funktioniert (und weshalb Mail-Forwarding eine schlechte Idee ist)
This is an article (in German because of it's specific audience) about SPF and DKIM features that prevent mail spoofing and it's effects on mail forwarding
Building a simple 3D printer (and what turned out to be not so simple)
This article describes some of the ideas and thoughts during building my first FDM printer and which lessions have been learned from that project.
How to handle LoRA messages from thethingsnetwork from JavaEE with TTNClientJ2
This article is a (really) short tutorial on how one can handle messages from LoRA nodes that are routed via thethingsnetwork inside an self-contained JavaEE application.
Adding tags for indexing webpages with Jekyll
An easy method to add tags to your static Jekyll generated pages and blogs
Linear stepper motor control - A summary
A short summary of the algorithms required for linear accelerated and decelerated stepper motor control on microcontrolers.
How to setup an TOR hidden service
A short description how to setup a TOR hidden service or an stealth hidden service and why one would want to do that even if one doesn't offer illegal content
Getting started with STM32F401RE Nucleo starter board on FreeBSD
How to get started with the STM32F401RE nucelo development board on FreeBSD with gcc and openocd
Using Sonoff basic switches with own firmware
Example how to flash Sonoff basic switches with custom firmware (using cli tools or the Arduino IDE)
Building a LoRA WAN gateway (and supplying data for the things network)
The following article leads the reader through building an LoRA-WAN gateway from an iMST ic880a concentrator board and an RaspberryPi. Optionally is shows the reader how to add GPS, enable remote configuration via the tinc VPN daemon and via a TOR stealth hidden service.
Android development on FreeBSD
How to get started with Android development on FreeBSD (using Android Studio)
Automatic domain validation TLS certificates with acme.sh and let's encrypt with own DNS servers
A tutorial on how to automatically manage TLS certificates for various services with DNS challenges and an zone served out of a bind zonefile that is protected via DNSSEC.
Speicherprobleme bei Android auf älteren Geräten umgehen
A short description of the davlik.vm.* tuneables for memory management tuning on Android devices
Verschlüsselter (Facebook) Chat mit Pidgin
A short description (in german) how to use the facebook chat with it's XMPP interface.
How to enable EAP-MD5 on Windows 7
A short description how to enable EAP-MD5 authentication for wired 802.1x authentication on Windows 7 since it has been (correctly) disabled for security reasons
