A fundamental part of system administration is configuring and managing users and groups. Part of this task involves monitoring the log in capabilities of all system entities. In this guide, we will introduce the ideas behind user management and authentication logging. We will be exploring these concepts on a Ubuntu server, but you can follow along on any modern Linux distribution Commands Used less /etc/passwd | grep messagebus sudo su messagebus sudo usermod -s /usr/sbin/nologin username sudo less /etc/shadow sudo passwd -l Username sudo less /etc/shadow | grep Username sudo passwd -u Username sudo touch /etc/nologin sudo sh -c 'echo "Planned maintenance. Log in capabilities will be restored at 1545 UTC" /etc/nologin' sudo rm /etc/nologin Useful Links VPS/VDS - https://www.mivocloud.com/