sshd config

/etc/ssh/ssh_config and /etc/ssh/sshd_config

In the latter, set some to control remote ssh login.

I.e.

Port 22
Protocol 2
PermitEmptyPasswords no
PermitRootLogin no  # can't login as root
AllowUsers xxx        # nobody can login except for xxx

For the last 2, login from a remote host, the server'll say 

'Permission denied, please try again.'

As u didn't input the right password.