Setup Warning “Login Banner”
Banner is nothing just a warning message or displays some message about the device. If you try to login remote machine, you can set some message before login the device.
Check Out : SSH Password less login Using SSH Keygen
Create a file under /etc directory
Type some authorised message here in this file
Go to /etc/ssh/sshd_config file to set this banner path.
Check Out : Create SSh Key
Restart the service of sshd
systemctl restart sshd
Now login remotely, You will see this message