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