onenetd is a single-port inetd. Invoke it as onenetd -h for options,
or see the included manual page.

onenetd was inspired by D. J. Bernstein's tcpserver program from
the ucspi-tcp suite, and is broadly compatible with it. Compared
to tcpserver, onenetd is missing support for access control, IDENT
lookups and DNS resolution, but adds IPv6 support and the ability
to refuse connections with a fixed response once the connection
limit is reached.