Cache Busting

Nov. 12, 2020


In the internet today almost everything gets cached. Every website you visit uses some caches. Either it is only a webserver filecache or one of the big players on market like cloudflare, fastly, keycdn, acamai or any other. In these cache systems static files can be stored for very long periods of time before it ends up expiring. But what happenes if you make any change, since the cached version of the file is stored in your visitors' browsers, they may be unable to see the changes made.

Cache busting solves the browser caching issue by using a unique file ...

High availability UniFi Controller

Aug. 13, 2020    Tags: raspberrypi  high available  unifi


I like having stuff high available. Everybody who works in IT knows it: Everything can fail and it most likely fails when you really need it as written in Murphy's law: "Anything that can go wrong will go wrong". Therefore I decided to cluster my UniFi Controller today. For sure it does not need to run on a server and can be started locally for configuration. But I like to have some nice stats and graphs which are also provided by the Controller and therefore it needs to be up and running constantly.

Remove Files completely from Git repository

Delete a file completely from Git history

March 11, 2020    Tags: git


It can happen that you add some big files to Git (binaries, documents, images, ...) or some "private" files which should not be in git. Removing it from your filesystem with a single commit will just remove the file in the working tree, but Git does not fully delete a file when removing it via commit. Maybe you want to restore it. That's why Git keeps it in his history.


June 11, 2019    Tags: raspberrypi  unix  pi  debian  tracker  advertisement  pi-hole


Online advertisment is everywhere. I don't like webpages where everywhere something pops up or overlays content or you can't really see any content because of the advertisment. On my browsers I like using plugins like AdBlock, uBlock Origin and NoScript. But what can I do on my smartphone inside the Apps or on my Smart-TV?

Yubikey two factor authentication for ssh

March 8, 2019    Tags: yubikey  2fa  ssh  yubico


After my successfull sudo test I was interested in 2fa for ssh. As a systemadministrator you are always scared about secure login just for you/your team.

Also ssh 2fa via yubikey is pretty straight forward. It needs some more work than just the sudo case but here we go.

Yubikey for sudo 2 Factor Auth

Dec. 7, 2018    Tags: yubikey  2fa


Some days ago I thought about testing two factor authentication (2FA) with Yubikey. Yubikey is a hardware security key which can do a lot.

How to test 2FA on a local machine if you don’t want to log you out or destroy anything important? I decided to implement 2FA for sudo command with yubikeys U2F feature. Be aware: This does not work for ssh.