Hi,

After I tried to add Public Key Authentication, then I added the pubic key to the new remote user following by changing the permitrootlogin to "NO" as this tutorial said :
https://www.digitalocean.com/community/tutorials/initial-server-setup-with-centos-7

when I tried to reload the ssh to apply the new setting, it doesn't and I got this error :

Redirecting to /bin/systemctl restart  ssh.service
Failed to restart ssh.service: Unit ssh.service failed to load: No such file or directory.

I tried to restart it using these both commands

systemctl reload sshd
&
service ssh restart

but it didn't get restarted. When I checked it's status, I found that it's active and running. so what's the solution to solve that and restart it ?

Thanks