If you want to have a password-less access
edit in the home directory the $HOME/.rhosts
and add the nodes, from which access is allowed.
Better chmod 600
This approach works for root and user access.
If you really need root access,
edit the /etc/securetty
and add some lines with pts/0 ... pts/n
In principle, on can use netgroups, probided by NIS
Another way only works for user accounts.
Edit the /etc/hosts.equiv
add a line
This does not work for a root account!