If your gnatsd will be started by inetd (the "internet daemon"), add the following entry to your /etc/inetd.conf:
# port userid program support stream tcp nowait gnats /usr/local/libexec/gnats/gnatsd gnatsd
and to /etc/services:
support 1529/tcp # GNATS
(You may need to use tabulator characters to separate the fields of
/etc/services.) Then send inetd a hangup signal
kill -HUP pid-of-inetd).
You may want to use another port instead of 1529 (see Port Number).