Servers

Cronjob: Basics and reboot

One of Linux five star things is the cronjobs. They allow you to automatically run stuf (scripts, applications, etc.) at quite specific times. The crontab is the place controlling when the stuff is run and you can list the crontab using the commaand crontab -l for the current user. If you want to edit the crontab, just use the command crontab -e and it launches the crontab in the default editor (set EDITOR env variable to change the editor used).

Ubuntu 16.04 to 18.04 TLS...

The site went offline a few hours today. Sorry. It turns out Ubuntu once again changed a major component and the upgrade path didn’t work as it should to keep the lights on after the upgrade. I’ve been updating the security settings on the server all around, and one of the things I wanted to do was adding TLSv1.3 support (and nothing before TLSv1.2). For that I needed, it seemed the best option to push forward the Ubuntu server version to the newer LTS version (18.

Linux - No space left on device, yet plenty of free space

My little server ran into an issue, and started reporting the error: No space left on device No worries, lest figure out which disk has full and clean up… Using the df command with the -h (for human-readable output) it should be easy to find the issue: root@server:~# df -h Filesystem Size Used Avail Use% Mounted on udev 483M 0 483M 0% /dev tmpfs 100M 3.1M 97M 4% /run /dev/vda 20G 9.

DNSSEC and switching nameservers

I’ve switched nameservers for all my domains yesterday. During the past many years I’ve been free-riding on GratisDNS and enjoying their free DNS service (and luckily never needed support in their forums). Yesterday I switched to Cloudflare and I’m using them for DNS for this (and other domains). I don’t have any particular requirements, and the switch was mostly easy and automated to the extent possible. Two domains went smooth, but the last my mahler.

Get your DMARC going

Get your company implementing DMARC now… During the past 5-6 years email industry efforts have been pushing the DMARC standard along. It provides the best widely supported and seemingly efficient way to - as a domain-owner - protect the domain from misuse and abuse in terms of spam and phishing attacks. As sending email has often been a wild-west, and knowing who is a valid sender of email may prove a challenge for many companies - and as most IT developers does seem to care too much about the finer details of email (and production just as bad email headers as HTML markup :-) ), implementing DMARC protection on your domain may actually be a challenge.