Inetd (Internet daemon) is a legacy service that listen for network connections for some other daemon. For example, inetd may listen for DNS connections on port 53 for the DNS daemon.
Inetd is no longer found is most modern distributions, and has mostly been replaced with xinetd (extended Internet daemon).
The inetd configuration file is located at /etc/inetd.conf. Files in the /etc/inted.d/ directory also control the behavior of inetd. Let's consider this example line in the /etc/inted.conf file.
dns stream tcp nowait root /usr/sbin/tcpd /usr/sbin/in.bind -l
When field 6 of the /etc/inetd.conf file is /usr/sbin/tcpd, the TCP deamon is being used. If tcpd is being used, when a remote client submits a request to the server for a service, the /etc/hosts.allow and /etc/hosts.deny files will be checked to determine if the client is allowed or denied access to the deamon. If allowed, the TCP deamon calls the server program into action.