The hosts.hfaxd file entry in the spooling area will be symlinked to the location given here. This file must exist and be readable only by the uucp user. See hosts.hfaxd(5) for details. This configuration permits access for all users:
environment.etc."hosts.hfaxd" = {
mode = "0600";
user = "uucp";
text = ".*";
};
Note that host-based access can be controlled with config.systemd.sockets.hylafax-hfaxd.listenStreams; by default, only 127.0.0.1 is permitted to connect.