This is an introduction on how to improve your security of your Linux server. The mentioned applications are available for Ubuntu 16.04 and newer.

Coturn is a turn and stun server that can be used for e.g.: VoIP. It allows you to create a connection between clients that are behind a NAT or in different networks.

This error 1236 ("Got fatal error 1236 from master when reading data from binary log") means that there is inconsistency in the file "mysql-bin.index" of the slave server.This is part of the MySQL Replication series.

How to setup Go-neb (latest version). This is a chatbot (chat bot) that provides services such as The automatic sending of RSS news feeds, searching for GIF images or information from Wikipedia and many other functionalities. The chatbot is easy to set up and can then be used via the messaging client Riot (client for the matrix server).