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.
netstat -abn or netstat -a -n -p tcp -o