how to login linux without password

a@A:~> ssh-keygen -t rsa
a@A:~> ssh b@B mkdir -p .ssh
b@B's password:
a@A:~> cat .ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'
b@B's password:

sumber http://linuxproblem.org/art_9.html