Duplicate window display on 2 screens with X.org

As an engineering school teacher and technical lecturer, I’m often asked to give demonstrations, in addition to the classic slide show. Like any organized lecturer, I can’t do without my notes, elapsed time, etc., which are given to me by presenter screen software. This kind of software requires an extended display, i.e. the computer screen and the video projector display 2 different things. The disadvantage of demonstrations is that the application window you want to show cannot be displayed on both screens at the same time. [Read More]

Unveiling Whiteout Files: Do you know how file deletions are handled between layers of a Docker image?

Unveiling Whiteout Files: Do you know how file deletions are handled between layers of a Docker image?
Union file systems are a mechanism for merging two or more file systems, to present them unified, under a single mount point for the user. The main idea behind this mechanism is to be able to alter the contents of the first file system (e.g. the contents of a CD-ROM) by writing all changes (additions, deletions, modifications) to the second (which could be a disk partition, a USB stick, …). [Read More]

Unify HTTP requests and GRPC calls on a single domain for more flexible configuration: example with Woodpecker

Unify HTTP requests and GRPC calls on a single domain for more flexible configuration: example with Woodpecker
I installed the continuous integration service Woodpecker, to replace DroneCI, which the company that bought it decided to bury. As Woodpecker is a fork of the latest free version of Drone, its use is broadly similar. However, the teams have taken different directions on certain aspects, and communication with agents/runners, which used to be via websockets, is now carried out in Woodpecker using the GRPC protocol. The solution proposed by the Woodpecker documentation is to use 2 domains: one will be used for the web interface and the REST API, the second will be used for GRPC. [Read More]

Using Waveshare e-ink screens without Raspberry Pi

Using Waveshare e-ink screens without Raspberry Pi
When it comes to e-ink displays, Waveshare is a rare manufacturer that allows you to buy displays of any size. Advertised as ESP32, Arduino and Raspberry Pi compatible, they are in fact compatible with any development board exposing the SPI protocol. Since Raspberry Pi boards have become hard to find in recent months, we’ll take a look in this article at how to use another Linux-based board to run a Waveshare display. [Read More]

Gamification of a Linux system administration course

Gamification of a Linux system administration course
System administration isn’t something that’s obvious to everyone, and it’s a subject that, when it’s more to do with the basics of networking and Linux, can seem a lot more daunting than learning about the latest trendy technologies (Docker, Terraform, Kubernetes, etc.). Also, with the bombardment of information and easy access to computer content and tutorials often more interesting than “classic” lectures, students are less and less attentive, present or participating. [Read More]

Self-hosting: for a decentralized and responsible Internet

Self-hosting: for a decentralized and responsible Internet
In an idealized world, we would all be free to access any service, made available by a community motivated by the common good rather than by the penurious enrichment of a few. However, we don’t live in that world. Today, everything is monetized: the smallest product or service only exists if it brings in enough money, without regard for the common good. The apparent gratuity of digital services is often accompanied by a more discreet but lucrative counterpart: the exploitation of our personal data. [Read More]

Give IPv6 connectivity to its Docker containers using an IPv6 block from its ISP

It may seem surprising that a modern service like Docker does not offer IPv6 in containers by default, especially when in a network with IPv6. In fact, for the same reason we saw in the introductory article, since the containers are in a virtual network, they cannot be reached by the box/router distributing the IPv6 subnet. The same phenomenon can be observed with IPv4: each container has an IPv4 in a subnet separate from the one in which our host machine is located. [Read More]

Use the additional IPv6 blocks of the Free and Orange network

With Free and Orange, when IPv6 is not disabled, the Freebox (and some Livebox) provide a /64 IPv6 range to the connected equipment. But it turns out that it is a /60 range that is available and usable by each subscriber. This represents a total of 8 addressable /64 networks. Let’s see what it can be used for and how to use it. IPv6 reminders Contrary to IPv4, with IPv6 one avoids making NAT, i. [Read More]

Multi-Hosts TLS Certificate

It is sometimes convenient to have a domain distributed over two or more machines. This technique, as old as DNS, is interesting to spread the load between multiple hosts, or to provide a bit of high availability. Indeed, if a host becomes inaccessible, at least half of the requests will continue to be successful.

However, since TLS connections have become the norm, and certificates should be renewed automatically, it could be hard to control the validation and the distribution.

I will present you a technique which, with the help of a finely configured web server, allows to get a different certificate on each machine, but usable for the same subdomain.

[Read More]

RTL8153B support for 4.9 kernel

If you buy a recent USB to Ethernet adapter, embedding a Realtek chip, you possibly face, like me, the following error, when connecting it:

r8152 4-1.1:1.0 (unnamed net_device) (uninitialized): Unknown version 0x6010
r8152 4-1.1:1.0 (unnamed net_device) (uninitialized): Unknown Device
[Read More]
kernel