My sysadmin notes

[dn42] AS4242420263 March 2026 update, FOSDEM talk and POPs

Thu, 26 Mar 2026 00:00:00 +0000

In this post, I’ll update you about the state of my dn42 network in 2026. Many things happened, I’ve lost a few POPs and will create a new one, but mainly, I had the opportunity to present my work on dn42 automation at FOSDEM'26!

About me

Thu, 26 Mar 2026 00:00:00 +0000

Hello! My name is Hyacinthe Cartiaux. I’m based in Moselle, France, and I enjoy traveling and (b|h)iking around the Greater Region.

With more than 15 years’ experience in systems and network administration and High Performance Computing, I currently work at the University of Luxembourg as a HPC architecture and infrastructure engineer. My job is to administrate the platform, maintain our systems in operational condition and participate in the design and evolution of the entire infrastructure (network, storage systems, compute nodes, devops stack, user services, etc).

[dn42] AS4242420263 under the hood - more POPs, full mesh network and auto-peering service

Wed, 04 Jun 2025 00:00:00 +0000

This post describes the internals of my current dn42 network, with the extension from 2 to 7 POPs, and last but not least, the creation of a SSH-based auto-peering service.

My Archlinux installation notes

Tue, 13 May 2025 00:00:00 +0000

I’ve just received my new Dell Pro Max 14 MC14250, and this is my installation notes for a modern Arch Linux installation, to support Secure Boot, Unified Kernel Images, systemd-boot, btrfs with snapper for snapshotting, and finalize the installation using aconfmgr, a simple configuration management system. The instructions are not detailed, the explanations are in the external resources listed at the end.

Create a private network with Headscale and Tailscale

Thu, 30 Jan 2025 00:00:00 +0000

This post describes the usage of headscale and tailscale to create a virtual network based on WireGuard.

Home of Flip Flap Network @ dn42 - AS4242420263

Thu, 02 Jan 2025 00:00:00 +0000

What’s Flip Flap Network

AS4242420263, aka Flip Flap Network, is my own experimental network on dn42. dn42 is a decentralized network mainly used as a testbed, it employs common networking protocols (such as BGP, DNS, WHOIS) to reproduce an Internet-like network. Most network links are configured using VPN tunnels (WireGuard) over the Internet, as such dn42 is an overlay network.

Nodes information

Clearnet

Location	FQDN	Clearnet IPv6
Amsterdam (NL)	`nl-ams1.flap42.eu`	`2001:bc8:3feb:100::9`
Amsterdam (NL)	`nl-ams2.flap42.eu`	`2001:bc8:3feb:100::6`
Paris (FR)	`fr-par1.flap42.eu`	`2001:bc8:710:c528:dc00:ff:fea5:d269`
Warsaw (PL)	`pl-waw1.flap42.eu`	`2001:bc8:1d90:1293:dc00:ff:fe25:1b13`
New York (USA)	`us-nyc1.flap42.eu`	`2a10:ccc2:1337:d42::cafe`
Frankfurt (DE)	`de-fra1.flap42.eu`	`2a13:e3c1:400e:d42::cafe`
Toronto (CA)	`ca-yto1.flap42.eu`	`2a11:6c7:2600:500:d42::cafe`
Rennes (FR)	`fr-rns1.flap42.eu`	`2a00:5884::42:4242:263:1`

dn42

Hostname	IPv6 Network	IPv6 Gateway	IPv4 Network	IPv4 Gateway
`nl-ams1`	`fd28:7515:7d51:a::/64`	`fd28:7515:7d51:a::1`	`172.22.144.160/29`	`172.22.144.161`
`nl-ams2`	`fd28:7515:7d51:b::/64`	`fd28:7515:7d51:b::1`	`172.22.144.168/29`	`172.22.144.169`
`fr-par1`	`fd28:7515:7d51:c::/64`	`fd28:7515:7d51:c::1`	`172.22.144.176/29`	`172.22.144.177`
`pl-waw1`	`fd28:7515:7d51:d::/64`	`fd28:7515:7d51:d::1`	`172.22.144.184/29`	`172.22.144.185`
`us-nyc1`	`fd28:7515:7d51:e::/64`	`fd28:7515:7d51:e::1`	`172.22.145.160/30`	`172.22.145.161`
`de-fra1`	`fd28:7515:7d51:f::/64`	`fd28:7515:7d51:f::1`	`172.22.145.164/30`	`172.22.145.165`
`ca-yto1`	`fd28:7515:7d51:9::/64`	`fd28:7515:7d51:9::1`	`172.22.145.168/30`	`172.22.145.169`
`fr-rns1`	`fd28:7515:7d51:8::/64`	`fd28:7515:7d51:8::1`	`172.22.145.172/30`	`172.22.145.173`

Hosted services

Service	Hostname	IP(s)
DNS v4	`ns1.hcartiaux.dn42`	`172.22.144.161`
DNS v6		`fd28:7515:7d51:a::1`
DNS v4	`ns2.hcartiaux.dn42`	`172.22.144.177`
DNS v6		`fd28:7515:7d51:c::1`

Peering

Policy

Flip Flap Network is open to all peering requests. Each peering systematically uses:

Benchmarking NVMe-based storage with fio, bench-fio and fio-plot

Fri, 01 Nov 2024 00:00:00 +0000

This post describes the usage of fio, bench-fio and fio-plot, to conduct a benchmark campaign and produce nice graphs. The tested system is a Dell R760 with 2 PERC 12 cards and 12 NVMe drives. The objective was to evaluate the impact of using hardware RAID on NVMe drives.

Linux from scratch... in a qcow2 disk

Wed, 25 Sep 2024 00:00:00 +0000

Linux From Scratch is a book which provides step-by-step instructions for building a GNU/Linux system entirely from source code.

I’ve always wanted to build my own LFS, to improve my understanding of GNU/Linux system architectures, but at the same time, I don’t want to break my laptop. I’ll describe in this post all the deviations from the book to build and boot a LFS virtual machine.

[dn42] AS4242420263 configuration - monitoring with LibreNMS (Part 5/5)

Sun, 08 Sep 2024 00:00:00 +0000

This article is the 5th part of my dn42 experiment. The objective is to monitor, graph and visualize the network flows in a network weathermap using LibreNMS.

[dn42] AS4242420263 configuration - DNS with bind (Part 4/5)

Sun, 01 Sep 2024 00:00:00 +0000

This article is the 4th part of my dn42 experiment, it describes the configuration of a primary and secondary DNS servers, using bind under Debian 12.

[dn42] AS4242420263 configuration - Multi-{pop,homing} (Part 3/5)

Wed, 14 Aug 2024 00:00:00 +0000

This article is the 3rd part of my dn42 experiment, it describes the configuration of a second router (“multi-pop”) and the addition of more BGP peering links (“multi-homing”), using an internal peering link between both routers.

[dn42] AS4242420263 configuration - speedrun to the first peering session (Part 2/5)

Wed, 24 Jul 2024 00:00:00 +0000

This article is the 2nd part of my dn42 experiment and will present all my configuration notes from the initial set-up of my first router server to my first peering session on dn42.

[dn42] AS4242420263 configuration (Part 1/5)

Mon, 15 Jul 2024 00:00:00 +0000

dn42 is a decentralized network, which employs Internet technologies (such as BGP). It is an ideal testbed to manipulate networking technologies without the pressure of running a public AS. This article is the start of my journey to dn42, from the request of my AS number and IP ranges to the monitoring of my peering links.

Bootstrapping VMs on a virtualization server using Terraform and cloud-init (Part 2/2)

Fri, 05 Jul 2024 00:00:00 +0000

In the first part, we have set-up a cheap virtualization server on a dedibox. My next objective was to use my cheap server to spawn VMs, instead of buying expensive VPS or cloud instances. For this matter, I use Terraform, and I’ve published my Terraform configuration on github.

Extend a partition on an OpenBSD system

Wed, 01 May 2024 00:00:00 +0000

This post is a method to extend the last partition of the disk layout (usually) to use all the available disk space on an OpenBSD system.

Podman cheat sheet

Sat, 20 Apr 2024 00:00:00 +0000

This is a cheat sheet of podman useful information and commands (updated in August 2025).

Turing complete - self documentation

Wed, 17 Apr 2024 00:00:00 +0000

This is my documentation for my own game of Turing Complete. Turing Complete purpose is to guide you through the implementation of a simple CPU, from the first logical gate to your assembly language definition.

Set-up a virtualization server with Debian, KVM/libvirt and IPv6 on a Dedibox (Part 1/2)

Mon, 11 Mar 2024 00:00:00 +0000

The objective is to set-up a virtualization server on a dedibox server with IPv6 support at NATed IPV4.

I use this configuration as a cheap “home lab” virtualization server.

BOINC - Berkeley Open Infrastructure for Network Computing

Sun, 10 Mar 2024 13:00:00 +0200

Berkeley Open Infrastructure for Network Computing is an open-source middleware system for volunteer computing (a type of distributed computing).

The client can be installed on any Debian system and used to join any BOINC project (PrimeGrid, Science United, etc).

Update LineageOS from 16.0 to 17.1 on the OnePlus 6T (fajita)

Sun, 10 May 2020 17:46:06 +0200

Updating from 16.0 to 17.1 on A/B devices without data loss can be tricky, especially with the OnePlus 6T…

Here are my upgrade notes.