Add user filtering with AllowUsers option in sshd_config file:
AllowUsers johndoe@192.168.1.* admin2@192.168.1.* otherid1 otherid2
This allows johndoe and admin2 only from 192.168.1.* addresses and otherid1, otherid2 from anywhere.
Checking Local Root Account Status Run sudo passwd -S root : Look for the status letter in the output. An L means the account is locked (...