By default, the tracker is run in "private" mode using a whitelist access.
You need to explicitly list all of the torrent hashes that you want to announce
into the /etc/opentracker/whitelist.txt file.

If you want to switch to "public" mode, allowing to announce any torrent hash,
you must recompile the package. You need to comment the
FEATURES+=-DWANT_ACCESSLIST_WHITE option and uncomment the
FEATURES+=-DWANT_ACCESSLIST_BLACK option in the debian/rules file.

Switching to "public" mode is not recommended by the package maintainer.