IP6M uses Atftpd package for tftp service. Since Atftpd doesn't support IPv6, we need Xinetd to run it.
Installing atftpd:
sudo apt install atftpd
Xinetd configuration (/etc/xinetd.d/tftp) for Atftpd is the following:
service tftp
{
socket_type = dgram
protocol = udp
port = 69
wait = yes
user = www-data
server = /usr/sbin/in.tftpd
server_args = /var/www/drupal8/private/tftp
disable = no
}
Most interesting option is the "server_args" option, that points to the private files directory under the Drupal instance. This is where the Drupal application creates the cable modem configuration files, and atftpd serves them to cable modems.