image Fields of interest

On this page you will find some of my works and files. Before using them please read copyright license and disclaimer of liability.

New blogs and articles

Information technology / computer programming


  • sudox (sudo for X) is  a bash script that executes commands under X in UNIX and LINUX as an arbitrary user with sudo. It provides  the necessary privileges using xauth over a pipe. I use it for example to execute firefox as  a different user with low privileges. Maybe you use sux allready. So what sux is to su, sudox is to sudo.

secbak, secrest
  • secbak and secrest are scripts for use with afio a cpio replacement. The scripts implement incremental multi-volume backups and restore. Unlike with tar, files are compressed individually and can be optionally encrypted.

Publish only PUBLIC marked subtrees
  • is a bash script that reconstructs parts of a UNIX or LINUX directory tree with symbolic links. I use it in order to publish automatically selected parts of my hard disk on a web server. Only files and directories within folders named PUBLIC are published.

lnr -s
  • lnr -s is a bash script which creates symbolic links with the same syntax then the UNIX command ln -s. Unlike ln -s it searches the shortest relative path between the source and destination and creates the link with a relative path. Most of the time symbolic links are very short in distance and used mainly to reduce redundancy. The advantage of relative symbolic links is that the whole directory can be moved without breaking the links. If you do so, please make sure that directory you want to move does not does not contain relative links pointing ourside of the moving directory.



C / C++



Additional European circuit stencils


Java transcoder
  • Transcoderjava is a tool to change the encoding of all *.java files in directory tree after having checked the encoding of the input files.

  • Transcoderjava est un utilitaire de transcodage. Il permet de changer le codage de tout les fichiers *.java dans une arborescence en même temps après avoir vérifié le codage des fichiers d’origine.

Java tool collection
BlueJ CNPI edition
  • BlueJ CNPI edition is a fork of the unchanged BlueJ Sources especially configured to fit our class room needs. This version requires Java 7!
    The main differences between the original and this distribution:

    1. Support for netbeans-swing applications: Open, compile and execute Netbeans-Projects directly:

    2. General support of UTF-8 and usage of utf8 in writing and reading files for all supported operating systems.

    3. Extensions Klassenkarte.jar and MainRunner.jar are packed in.

ICT security

Estonian ID Card Software
  • Estonian ID Card Software binaires for Debian 7: RIA ID-card software_ v3.7.2 compiled for Debian 7.2 (wheezy) following this howto (author: Martin Paljak).

    You can add this PPA with the following terminal command (just one line):

    sudo sh -c "echo 'deb link:./public/downloads/software/repository/ ./'
               >> /etc/apt/sources.list"
    The packages are not signed. Please ensure integrity and authenticity by verifying their sha256 sums. This is highly security relevant software. Please do not trust any non-official source and use these binary packages only if you know me in person.
Comparison of Tropos modelling techniques

IPv6 server support for IPv6
  • The web-server supports the Internet Protocol version 6 (IPv6). In order to access this site via IPv6 your operating system and Internet Service Provider must also support IPv6. You can test this precondition here. Having 10/10 points your IPv6 connection works fine. It depends on your system settings if IPv4 or IPv6 is used by default. The firefox addon IP6 or not shows your current connection type.

    IPv6 only networks are easy and secure. Address Family Translation (AFT) allows a gradual migration to IPv6 by providing seamless Internet experience to greenfiled IPv6-only users, accessing IPv4 Internet services. This very good article explains the NAT64 gateway technology. Cisco ASR 1000 Series router run NAT64. An open source implementation of NAT64 can be found here.

Linux configuration files

Debian 7 Wheezy configuration files
  • A selection of my configuration files can be found here. They are tested with Debian stable, but should work with most other distributions too.

i3 window manager extensions
  • i3 is a tiling window manager for advanced Linux users. This article (pdf) presents

    • a file-manager extension,

    • an exit-mode extension and

    • a pass-through-mode extension.

    The source code of the suggested i3 extensions: /etc/i3/config.

Howtos and manuals

Debian 7 UEFI boot
Debian 7 mount encrypted logical volume
Linux Restena VPN
  • Connect-Linux-to-Restena-VPN-howto-2 is a German step by step manual for Linux users to connect to the Restena Virtual Private Network (VPN). It is only useful for Restena members who are living outside of Luxembourg and want to use the fichier élèves application. The obsolete Version 1 of this document in French is still available here.  

Linux Luxtrust
  • A short manual explaining the installation of the Luxembourgian Luxtrust Signing Stick on Ubuntu 09.10 Karmic Koala. It has been reported that it also covers Ubuntu 10.04 (lucid).

Redirect the sound of an application
Secure Computer Cluster Administration with SSH


Patches of various software
  • My patches of various software can be found here.


ASN.1 tiny decoder
  • ASN.1 tiny decoder is a simple and fast ASN.1 decoder without external libraries designed to parse large files.

    There is a good “Pyasn1” ASN.1 python library out there. It is quite complete, but learning how to use it is very time consuming. Furthermore Pyasn1 is not designed to parse large files. This why I wrote this tiny ASN.1 decoder. It’s design goal was to be as fast as possible (with Python). Download here.

Fast search in large CRL

Pedagogy / study materials

Java exercises for beginners
  • Java à l’école is a collection of Java BlueJ exercises for A-level students in French.

  • Java à l’école est un recueil d’exercices pour débutants sans connaissances d’autres langages de programmation. Contrairement à d’autres méthodes didactiques les exercices introduisent directement les bases de la programmation orientée objet en respectant le concept de programmation "Architecture Modèle/Vue/Contrôleur".

Java teachers guide
  • Java teachers guide is a short computer teachers guide how to write Java exercises. This document is in German.

  • Astuces Java pour enseignants est un ensemble de recommandations destinés aux professeurs d’informatique pour écrire des exercices en Java.

  • Java Tipps für Lehrer ist eine Sammlung von Empfehlungen und Richtlinien für Lehrer zum Erstellen von Schülerübungen. Die Tipps sind das Ergebnis einer Analyse der häufigsten Lehrerfehler beim Umstieg von der prozeduralen Programmierung zur objektorientierten Programmierung.

Oscilloscope screenshot generator
List of free school fonts
  • What computer fonts are suitable for learning handwriting in an international learning environment? The free school fonts list aims to meet the following requirements:

    • comparability with most European text books for beginners (lowest common denominator),

    • all European characters available,

    • excellent typographic quality,

    • real free font without restrictions (see licence),

    • ease of usage.

    To install and use the above fonts on your computer download the free-font-archive and follow instructions in How to use Bienchen handwriting font and How to use Deutsche Normalschrift handwriting font.

    Some fonts did not make into our final selection because they do not meet fully all our above criteria. They may be right for you: List of free alternative fonts.

  • Welche Computer Schriften eignen sich zum Erlernen des Schreibens mit einer internationalen Lernergruppe oder verbessern der Handschrift? Die Liste freier Schulschriften erfüllt die folgenden Kriterien:

    • Übereinstimmung mit den meisten europäischen Schulbüchern für Anfänger (kleinster gemeinsamer Nenner),

    • alle europäischen Zeichen verfügbar,

    • hervorragende typographische Qualität,

    • wirklich freie Schrift ohne Beschränkungen (siehe Lizenzen),

    • einfache Handhabung.

    Um die Schriften auf Ihrem Computer zu installieren, laden Sie bitte das Freie Schriften Archiv herunter und folgen den Anleitungen in How to use Bienchen handwriting font und How to use Deutsche Normalschrift handwriting font.

    Einige Schriften haben es nicht in unsere Finalauswahl geschafft, da sie nicht gänzlich alle der obigen Kriterien erfüllen. Sie könnten aber die richtige Wahl für andere Anwendungszwecke sein: Alternative Liste freier Schriften .


Transactional Analysis


Music / Dance

On stage
  • Jens Getreu and friends performing Tuulevaiksel ööl (2011). Please choose your preferred video encoding: flv (needs flash plugin), webm (preferred for Firefox, Opera), avi or mpeg.

Estonian music sheets

Student pages

A website for my students with additional instructional materials:

Lycée Josy Barthel Mamer
  • Website for LJBM students.

Tallinn European School
  • Website for TES students.

I grant to you a worldwide non-exclusive royalty-free revocable license to:

  1. view this website and the material on this website on a computer or mobile device via a web browser;

  2. copy and store this website and the material on this website in your web browser cache memory; and

  3. print pages from this website for your own personal and non-commercial use.

The bash, gnuplot (and other) computer scripts and dia stencils published on this website are licensed under GPLv3. For other software see copyright notice inside the source packages.

I do not grant you any other rights in relation to this website or the material on this website. In other words, all other rights are reserved.

For the avoidance of doubt, you must not adapt, edit, change, transform, publish, republish, distribute, redistribute, broadcast, rebroadcast or show or play in public this website or the material on this website (in any form or media) without my prior written permission.

Disclaimer of liability

The material, programs and information contained on this website are for general information purposes only. You should not rely upon the material or information on the website as a basis for making any business, legal or any other decisions. Whilst I endeavour to keep the information up to date and correct, I make no representations or warranties of any kind, express or implied about the completeness, accuracy, reliability, suitability or availability with respect to the website or the information, products, services or related graphics contained on the website for any purpose. Any reliance you place on such material is therefore strictly at your own risk. I will not be liable for any false, inaccurate, inappropriate or incomplete information presented on the website.

In a nutshell: enjoy and make this world a better place ;)

Please check files for consistency referring to their sha256 message digests.

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