Applications are running either as stand alone daemons:
Apache, SSH, Postfix, Samba, BIND, DHCP...
or started through application servers such as inetd or xinetd: telnet, rsh,
rlogin, ftp, imap, pop3 ...
The services are usually controlled by systemd, the master service.
To start and stop such services, use commamd systemctl.
systemctl start inetd
systemctl stop inetd
To enable and disable the service in the system startup:
systemctl enable inetd
systemctl disable inetd