If it's a standard OpenSSH server, the configuration file is /etc/ssh/sshd_config. Search that file for the variable "PermitRootLogin" under the "Authentication:" section. The allows variables are: yes, no, without-password. Without-password is used when you have a key-based setup involved...which is a good idea for some systems.

On the client box:

ssh-keygen -t rsa
(accept defaults)
sftp/rsync/etc. the file ~/.ssh/id_rsa.pub to the server as /root/.ssh/authorized_keys.

On the server box:

Change sshd_config as desired
/etc/init.d/sshd (or equivalent) restart

Then attempt an SSH session from client to server. If the keys are probably in place you will not be prompted for a password.