xf.is blog

List of free ACME SSL providers

Published in ssl.

Updated 6.7.2020 Please note that many ACME clients only support Let’s Encrypt. Certbot should work with alternative ACME providers. Buypass Go SSL Norwegian certificate authority offering free SSL certificates valid for 180 days (Technical specifications). No wildcard certificates. ACME directory url: https://api.buypass.com/acme/directory Chains up to “Buypass Class 2 Root CA” valid until 2040 DNS CAA: […]

Configuring systemd user timer

Published in linux.

To run systemd timer jobs (cron) as a user you’ll need to create a systemd service folder as the user: By default, systemd will only run timers if the user is logged in so to be able to run timer jobs without logged in use we enable lingering session with Then you can drop the […]

haproxy: Monitor PostgreSQL for current master

Published in linux.

There are couple of methods for haproxy to monitor what PostgreSQL instance is currently master so that “dumb” clients can always write to a PostgreSQL instance (instead of connecting to the standby node). First there is the send-binary method by replicating the PostgreSQL V3 protocol but requires trusted connection and is TCP/IP only (no SSL). […]

vlan bridges in netplan

Published in linux.

Took me a while to figure this one out in the netplan yaml syntax: Bonus .vimrc settings for yaml

Pipe cron to syslog/journald

Published in linux.

Simple way to pipe cron script output to journalctl / syslog gives following in journalctl

Convert PostgreSQL cluster to use page checksums

Published in postgresql.

When upgrading PostgreSQL cluster from one major version to another you cannot use pg_upgrade tool to upgrade/convert cluster with page checksums disabled to a cluster with page checksums enabled. Instead you have to do dump and restore. On Debian/Ubuntu based systems this is made easier using the pg_createcluster / pg_dropcluster commands. Here I’m converting a […]

View CPU microcode revision from powershell

Published in windows.

A small powershell snippet to show what CPU microcode revision is running and what microcode revision the BIOS provides. Example output:

Blacklist bad memory addresses in Windows

Published in windows.

I recently experienced random MEMORY_MANAGEMENT BSOD on my personal computer. When consulting Microsoft Dev Center for the error code it indicated a issue with the RAM. The computer is 6 years old and only has 8 GB of RAM (two sticks) I’m not about to spend money to replace the RAM. I ran memtest86 and […]