In Module 110.2 of LPIC version 500, we are talking about host security. We start by seeing how shadow file secures your passwords and will continue with blocking shell access for some users (using /usr/sbin/nologin) or preventing all normal users from logging into the system (using /etc/nologin). Then I will convert the concept of Super Servers which might be called TCP Wrappers or Service Dispatchers. The older one is the inetd and xinetd. You can use /etc/hosts.allow or /etc/hosts.deny to control services if a service respects inetd using the libwrap library. Then we will cover a newer super service using systemd sockets and will finish by seeing how you can check and disable / stop unwanted / unused services. Attack surface is important; lets reduce it! 00:00 - Intro to lpic 110.2 version 500 01:20 - /etc/shadow 03:50 - Prevent shell login using /usr/sbin/nologin 05:00 - Prevent login using /etc/nologin 07:05 - Understanding / Why Super Server (TCP Wrappers) (xinetd) 13:30 - Control servers using hosts.allow & hosts.deny 15:40 - service despatching using systemd socket 18:30 - Removing unwanted linux services Full LPIC1 course:    • LPIC 1 (version 500) Course   Textbook: https://linux1st.com/1102-setup-host-security.html