Base64 encode on shell

Sometimes you need to encode a string  with a base64 encoding. For example when trying to send a HTTP request with a Basic Authentication header like that:

As you can see the Basic Auth username and password are included in the request as a base64 encoded string. On the Linux shell this string can […]

Mount a ssh filesystem under Linux or How I mounted my webspace into my root server

Today I had to mount a ssh filesystem under Linux. The reason was, that I had the perception that I would be a very cool idea, to use my old webspace package from, that I only kept because of the 10 included domains, as a backup storage for my root server. The plan was […]

Restrict root ssh access to a single IP under Raspbian / Debian / Ubuntu

Today I configured a new backup solution that required me to restrict root ssh access to a single IP for the root user. I got tis to work by going the following steps (on Raspbian GNU/Linux 9): login via ssh on the maschine to access via root modify the /etc/ssh/sshd_config like that

add the following […]

Setup monit behind Apache proxy under ISPConfig

Today I wanted to setup monit behind Apache proxy on my webserver, which runs ISPConfig ( under Debian. Monit is a OpenSource monitoring tool for Linux (see Requirements I had the following requirements on the solution: monit should only be accessible from the server itself (localhost) monit should run under a special SSL-secured URL (not IP:PORT as […]

Export or extract a certificate to or from PFX

Sometimes you have to deliver or you even get your server certificate files in the pfx file format (personal information exchange, see, that is commonly used in Windows based environments. The following paragraphs show, how to export or extract a certificate to or from PFX. Export cert to PFX In order to export the Certificate, Private Key and any […]

Get your public IP via shell

To get your public IP you can use websites like or just google for it ( But you can also get your public IP via the following Linux shell  command (the smart way :-D):

This gives you an output like that:

Or for IP address only output:

Example output:

To install get […]

Run a DynDNS client under Raspbian

For a home automation project I have to setup a local DynDNS client on my Banana Pi running with Raspian. Here are the steps I’ve taken to run a DynDNS client under Raspbian (will work on other Debian based Linux distributions too): Install ddclient package:

This command installs the package and starts the DynDNS configuration wizard. Select […]

Run dnsmasq as a local DNS Server (Arch Linux)

Dnsmasq is a very handy and easy to install DNS / DHCP server implementation, that uses the local hosts file to determine hostname to IP mappings. I use a local DNS to be able to call my local machines by a memorable domain instead of their IP. Additionally dnsmasq works as an DNS Cache. Installation of dnsmasq […]

Resolve problems with authorized_keys permissions

Sometimes I had problems to connect to a server via public key authentication. In most cases I could solve them by setting up the right permissions for the file and path of the authorized_keys file. This can be done as shown below:

“Could not resolve host” error

If you get this error message when trying to update the system (see example below) or just pinging an external host …

… you have to declare an default route: