In Raspberry Pi from version Jessie onwards the “root” login for SSH sessions (via Putty Login) has been disabled by default. It can be enabled by just editing “sshd_config” file and then restarting “ssh” service.
To start with login to raspi via ssh using the default “pi” credentials. Then elevate yourself to super user “sudo”
# sudo -i
Then edit “/etc/ssh/sshd_config” and update the field “PermitRootLogin”
# vi /etc/ssh/sshd_config
And then restart ssh service for the changes to take effect.
# /etc/init.d/ssh restart
You can also change the password for the root account by following these steps.
Login to raspi via ssh using the default “pi” credentials and the elevate yourself as super user “sudo” and run “passwd” to change the password.
# sudo -i # passwd root
root@raspi-quad:~# passwd root Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully