#На клиенте:
ssh-keygen -t rsa
ssh-copy-id -i ~/.ssh/id_rsa.pub youruser@remote.server.host
#На сервере отредактировать файл /etc/ssh/sshd.conf
# Should we allow Identity (SSH version 1) authentication?
RSAAuthentication yes
# Should we allow Pubkey (SSH version 2) authentication?
PubkeyAuthentication yes
# Where do we look for authorized public keys?
# If it doesn't start with a slash, then it is
# relative to the user's home directory
AuthorizedKeysFile .ssh/authorized_keys