On your machine
local $ ssh-keygen -t rsa
do not enter any keys, just hit Enter Enter. Next,
local $ scp ~/.ssh/id_rsa.pub root@ipaddress:/root/.ssh/authorized_keys local $ rm ~/.ssh/id_rsa.pub
local $ ssh root@ipaddress
that should guide you directly to the command prompt
UPD 20.04.2014: There is a great Linux program ssh-copy-id that does exactly everything mentioned above, but in one line instead!