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Comments are very welcome on bert@hubertnet.nl or @bert_hu_bert. Update: several constructive remarks have been used to improve this text. Thanks! In this post I will attempt to fully explain the Spectre and Meltdown vulnerabilities in an accessible way. I decided to write it up after I realised it took me more than a day to figure it out, even though I’ve been doing security related stuff on CPUs for 20 years.

Welcome to Kolmo There are three avenues to learn about Kolmo (GitHub). There are two Youtube videos, one from the most excellent NLNOG 2017, the other from the equally excellent UKNOF 38. These videos explain a lot of the the history and the ‘why’ behind Kolmo. There is also the kolmo.org website, which is ‘self-hosted’ by the ws Kolmo-powered webserver. Finally, there is this post, in which I focus on what Kolmo actually does, without spending much time on the ‘why’ or the history.

Some brief notes on making ethernet cables With thanks to the most excellent NLNOG for a lot of mostly correct advice! Friends will tell you “crimping” ethernet cables is easy. Most of your friends either have overly rosy memories, or have practiced on 200 cables before telling you it is now easy. It is not easy. This page is for if you have a few extra euros/dollars/coins to spare, and don’t want to spend rare hours of concentrated effort to crimp an ethernet cable using unfamiliar equipment and supplies.

Onlangs vond ik via LinkedIn een advertentie voor de vacature ‘Senior Category Manager Domestic Appliances’ bij bol.com. Hierin stond zoveel wartaal dat ik het de moeite vond een ‘best of’ selectie te delen op Facebook. Daar vond men het ook erg grappig. Desondanks is het de moeite waard de vacature te decoderen: wat staat hier nou eigenlijk? Of exacter, wat bedoelen deze mensen. Komt ie. Update: Inhoudelijke reactie van bol.com in De Telegraaf

DNA: The Code of Life At the most magical SHA2017 gathering I gave two presentations, “DNA: The Code of Life” and the followup, “DNA: More greatest hits” (slides). The first presentation was recorded by the wonderful CCC C3VOC streaming crew, the second one by my friend Bart Smit (who is also wonderful). Without making this post too long, I want to thank everyone who helped me do this presentation — a lot of people contributed time, advice, recording abilities, great questions and enthusiasm.

(Don’t) drop the hint: communicating with technical people This post is a subset of the presentation “Escaping the data center — tales from a recovering manager”. Video, slides. When we communicate at the office, we frequently do not directly say what we mean. A common conversation might go like this “Hey John, we did a survey and it turns out people can’t find what they are looking for on our website”.

On IP address encryption: security analysis with respect for privacy Frequently, privacy concerns and regulations get in the way of security analysis. I’m a big fan of privacy, but I’m also a big fan of security and preventing people from getting hacked. If you are hacked you have no privacy either. Per-customer/subscriber traces are extremely useful for researching the security of networks. Specifically, lists of DNS requests per IP address make spotting infected users or infected devices very easy, especially if you look at “yesterday’s traffic” and compare it to today’s threat intelligence.

On Linux vDSO and clock_gettime sometimes being slow Like the previous post on this somewhat dormant blog, I want to share an oddity I discovered that no search engine could really find for me - even though once I found what the problem was, it turns out I was by no means the first person to discover this. Some system calls that are used extremely frequently in Linux can be speeded up by a mechanism called vDSO: a virtual dynamically linked shared object.

So no matter how pretty your code, eventually someone will benchmark it and demand top performance. Squeezing microseconds is a very addictive and even destructive activity. It ruins your evenings, destroys your ability to converse with human beings and typically leaves your code in a mess. No programmer can escape it however: the world demands speed, or a somewhat equivalent modern measure, longer battery life. Squeezing out more performance is not just a matter of “writing better code”.

A meandering walk through innovation that also reviews a book This article is part of a series on (European) innovation and capabilities. I care deeply about innovation. It is literally where the future comes from, but it is a curious thing. Innovation and its more powerful partner, invention proceed at a snail’s pace. “In a world where change is the only constant” is a lie. It took this world 20 years to invent a decent can opener.

How many hours for multithreading the server? Or: dealing with overly detailed project planning Many developers, me included, dread that moment. Someone sits down with you and wants to know how many “hours” each step of the project will take. And of course the thing is, if you are doing something that has been done many times before, you might be able to provide a detailed estimate. People that build houses work like this, but they still often get it wrong.