[Unit]
Description=fast remote file copy program daemon
ConditionPathExists=/etc/rsyncd.conf
After=network.target
Documentation=man:rsync(1) man:rsyncd.conf(5)

[Service]
ExecStart=/usr/bin/rsync --daemon --no-detach
RestartSec=1

# Citing README.md:
#
#   [...] Using ssh is recommended for its security features.
#
#   Alternatively, rsync can run in `daemon' mode, listening on a socket.
#   This is generally used for public file distribution, [...]
#
# So let's assume some extra security is more than welcome here. We do full
# system protection (which makes /usr, /boot, & /etc read-only) and hide
# devices. To override these defaults, it's best to do so in the drop-in
# directory, often done via `systemctl edit rsync.service`. The file needs
# just the bare minimum of the right [heading] and override values.
# See systemd.unit(5) and search for "drop-in" for full details.

ProtectSystem=full
#ProtectHome=on|off|read-only
PrivateDevices=on
NoNewPrivileges=on

[Install]
WantedBy=multi-user.target