The actual configuration of inetd is done in /etc/inetd.conf, which has the following format:

service-name socket-type protocol wait-flag user server-program

Since services are specified in inetd.conf by service name rather than port, they must be listed in /etc/services in order to be eligible for handling by inetd.

Let's look at some common lines from /etc/inetd.conf. For example, the telnet and ftp services:

# grep ^telnet /etc/inetd.conf
telnet  stream  tcp     nowait  root    /usr/sbin/in.telnetd

# grep ^ftp /etc/inetd.conf
ftp     stream  tcp     nowait  root    /usr/sbin/in.ftpd -l -a

For both of these services, the configuration is to use the TCP protocol, and run the server (in.telnetd or in.ftpd) as the root user. For a complete explanation of the fields in /etc/inetd.conf, see the inetd(8) man page.