This article will help you if you have local server running and somebody needs to root ssh login only from your local network.
Open a terminal.
Edit the ssh config file located /etc/ssh/sshd_config
$ sudo vim /etc/ssh/sshd_config
Search for '# Authentication:' line and add the below lines inside that section.
# the following overrides the general config when conditions are met. Match Address 192.168.0.* PermitRootLogin yes
This will only allows root login from ips that are inside 192.168.0.* subnet.
Restart the ssh server
sudo service ssh restart