• How to do everything in ffmpeg

    This is everything I know to do in ffmpeg.

  • An internal chat service: Hundreds of users in a few locations

    An internal chat service is a great way to help your users connect with each other. There are many good options available online, both via SaaS and self-hosting. However, when self-hosting for many users, the effort required to do user account management may be prohibitive. This guide helps you skip that, in the case that your many users are spread out over only a few locations (and therefore, internet connections). We limit the availability of the chat service to only those IP addresses, and do away with all centralised user account management. We give every user the complete freedom to present themselves to other users as they wish, and only allow people in who we trust to play nicely. A nice side-effect of this approach is that the system can be run with only very limited day-to-day administration.

  • Using Mutt offline

    You are a happy Mutt user, and have been for while. When you have a stable internet connection, such as in the office, Mutt is a pleasure to use. However, when there is no active internet connection, Mutt does not work well if you store all your email online. This is a guide to use Mutt offline, syncing all data when the internet connection is available again.

  • Mijn mailserver is stuk: wat nu?

    Als de mailserver down is, gebruik ik de mailrelay zowel inkomend als uitgaand als backup-mailvoorziening.

  • Updating your Garmin Forerunner 735XT via USB mass storage

    Installing updates via Bluetooth on your Garmin Forerunner 735XT is really slow. Garmin Express is an alternative, but it doesn’t have a Linux version. Luckily, you can install updates via USB by uploading them to the Forerunner as a mass storage device.

  • Making HaveDane.net

    Use STARTTLS and DANE for your mail servers. The advice from RFC 76721 is easy enough to give, but harder to implement. For incoming connections, online verifiers are available (also here) that show whether you have properly configured your server and associated TLSA records. Outgoing connections are another matter. How do you scan an organisation’s outgoing mail connections? The answer: you ask people to send emails to a specifically prepared mail server and check which messages arrive.

    1. RFC 7672: SMTP Security via Opportunistic DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) 

  • From GPX track to Garmin course using GPSbabel

    You have a GPX track file from an external source and you want to run/hike/cycle it using your Garmin device. This does not work immediately, because Garmin Connect does not allow you to import GPS tracks as courses directly. However, Garmin does allow you to import tracks as activities and subsequently convert them to courses. We will use GPSbabel to turn the track into a fake activity and import it in Garmin Connect.

  • Use OpenVPN to connect a remote RasPlex-client to your Plex media server

    Plex is great. So is RasPlex, the Raspberry Pi distribution that is a fully-functioning Plex client. I would like to take my Raspberry Pi with me to be able to remotely connect to my server and view media.

  • Ubuntu-updates gaan niet meer: /boot is vol

    Je probeert updates te installeren op je Ubuntu-laptop, maar je krijgt de melding dat er te weinig ruimte is in /boot. Zo los je dit op.

  • Samsung-laptop start Ubuntu niet meer

    Je start je laptop op, en in plaats van je gewone opstartscherm zie je een grijs venster met ‘Boot Menu’ en ‘App Menu’ bovenin en drie opties waarvan er twee ‘Windows Boot Manager’ zijn. Je kunt niet werken. Dat is frustrerend. Dit is hoe je dit repareert.

  • Secure backups for your personal servers using duplicity and Amazon S3

    I wanted to make secure backups of a few servers, but none of the guides I found online sufficed for my purposes. I wanted the following:

  • Geavanceerde opdrachten voor beginnende systeembeheerders

    Beginnende systeembeheerders hebben eerst basiskennis nodig. Als ze die eenmaal hebben, kunnen ze zelf verder studeren op basis van internetbronnen om meer geavanceerde onderwerpen onder de knie te krijgen. Dit is een lijst van meer geavanceerde onderwerpen. De meeste van deze opdrachten zouden in een uur of minder uit te voeren moeten zijn. Voel je echter niet bezwaard als je er langer aan besteedt: des te meer leer je.

  • Een toegankelijke inleiding in systeembeheer

    Dit is een basiscursus om de beginselen van systeembeheer te verwerven. Hij is bedoeld voor mensen zonder kennis van Linux die zich wel comfortabel voelen met meer geavanceerd gebruik van hun computer.

  • Ubuntu 14.04: Your toolbar is gone

    You boot up your laptop, login, and then: poof, your toolbars are gone. This is annoying, and the advice you find online is quite erratic.

  • Verifying SSH fingerprints in new form

    We’ve all learned a few years ago that the MD5 hash function is no longer secure in many scenarios. Specifically, we should not be using MD5 to verify data, because an attacker may be able to construct two pieces of data with the same hash and feed us one when we were expecting the other.

  • Upgrading CyanogenMod on your encrypted Android phone

    You have problems installing CyanogenMod upgrades automatically. When you boot into recovery and try to apply the update manually, you run into problems because it “can’t mount /data”. This is because you have enabled full disk encryption on your Android device (good for you!).

  • Dear mailing list admin (please allow for DMARC)

    Dear mailing list admin,

  • Fristileaks of Whiskyleaks organiseren: Klein kernteam & bereikbare locatie

    Je bent een keer op Fristileaks of Whiskyleaks geweest. Of misschien wel een paar keer. Nu wil je meer: je wilt bij de harde kern horen, je wilt plezier voor je medemens scheppen of je hebt gewoon even niks te doen. Kortom: jij gaat de volgende Fristileaks of Whiskyleaks organiseren.

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