You want to add a new network service, controlled by inetd .
Add a new line to /etc/inetd.conf of the form:
SERVICE_NAME SOCKET_TYPE PROTOCOL THREADING USER /PATH/TO/SERVER ARGS
Then signal inetd to reread /etc/inetd.conf. [Recipe 3.4]
The values on the line are:
Service name. A service listed in /etc/services. If it's not, add an entry by selecting a service name, port number, and protocol. See services(5).
Socket type. Either stream, dgram, raw, rdm, or seqpacket.
Protocol. Typically tcp or udp.
Threading . Use wait for single-threaded, or nowait for multithreaded.
User. The service will run as this user.
Path to server executable.
Server arguments, separated by whitespace. You must begin with the zeroth argument, the server's basename itself. For example, for /usr/sbin/in.telnetd, the zeroth argument would be in.telnetd.
A full example is:
telnet stream tcp nowait root /usr/sbin/in.telnetd in.telnetd
A line in inetd.conf may contain a few other details as well, specifying buffer sizes, a local host address for listening, and so forth. See the manpage.
inetd(8), inetd.conf(5), services(5).