Category: How-to

  • Counting like a computer

    Counting like a computer

    Computers are very good at counting. But usually only within narrow limits. Here is an insight into where these limits come from and what goes wrong when they are exceeded.

  • Kensington PowerPointer for Linux LibreOffice

    Kensington PowerPointer for Linux LibreOffice

    Navigating the slides works perfectly with the Kensington PowerPointer for LibreOffice under Linux, no questions asked. The extra functions (“laserpointing”, drawing, and screen blanking) are not well supported. Here is how to fix them.

  • How to block AI crawlers with robots.txt

    How to block AI crawlers with robots.txt

    If you wanted your web page excluded from being crawled or indexed by search engines and other robots, robots.txt was your tool of choice, with some additional stuff like <meta name=”robots” value=”noindex” /> or <a href=”…” rel=”nofollow”> sprinkled in. It is getting more complicated with AI crawlers. Let’s have a look.

  • chrony NTS certificate reload

    chrony NTS certificate reload

    The chrony NTS daemon has no way to automatically reload its NTS certificate. A quick hack fixes this.

  • Data lifecycle questions, not only for Blockchains

    Data lifecycle questions, not only for Blockchains

    In any data-centric applications, understanding the data lifecycle (also as part of the product lifecycle) is important, especially when trust or traceability are also goals. If Blockchain should play a role, then the requirements associated with the data lifecycle can even become a decisive factor: Either adapt the data model or the processes, or, if…

  • Network Time Security: NTS articles overview

    Network Time Security: NTS articles overview

    NTP, the Network Time Protocol, is the way most computers and mobile devices obtain their time through. NTS (Network Time Security) is to NTP what HTTPS is to HTTP. It also is as easy to upgrade as upgrading to HTTPS is these days: No effort for the client, just adding a certificate for the server.…

  • Debugging NTS problems

    Debugging NTS problems

    Debugging is hard, debugging security protocols doubly so. And there are not many tools and how-to’s availabe for NTS yet. So, here’s a (short) list of NTS problems I have seen and some tricks for debugging them.

  • NTS and dynamic IP addresses

    NTS and dynamic IP addresses

    Good news is that NTS relies on DNS names, no longer “naked” IP addresses. But what happens when the DNS name changes, pointing to a different IP address? A look at the protocol, the Chrony source, and the implications.

  • Configuring an NTS-capable NTP server

    Configuring an NTS-capable NTP server

    The choice of Network Time Protocol (NTP) servers supporting NTS is still very limited. Here is some advice to get it to run smooth and trustworty.

  • Transparent, Trustworthy Time with NTP and NTS

    Transparent, Trustworthy Time with NTP and NTS

    «Time is Money», as the old adage says. Who controls the time, controls all kinds of operations and businesses around the world. And therefore, controls the world. Today, we all take accurate time for granted. Even though, today, it is delivered over the Internet mostly unsecured. But this is easy to change.