Protip: systemctl disable: disable from launching at boot time. If you want to make sure a service cannot be started at all, what you want is systemctl mask.
e.g., if the (insecure) rsync daemon could be running at the moment, these three should have you covered:
sudo systemctl stop rsync
sudo systemctl disable rsync
sudo systemctl mask rsync
(PS. Yeah, you really shouldn’t be running the rsync daemon. And you don’t need it to use rsync over ssh.)
@aral systemd systemctl tip:
enable, disable, and mask all accept "--now" to also apply the setting to the running system at the same time.
So, to mask rsync, it can be shortened to one command:
sudo systemctl mask --now rsync
@aral (Personally, I think systemd state and similar things, such as firewalld, shouldn't have a distinction between doing something and having it persist across reboots. It should all be in sync. Anyway…)