Linux Passwordless SSH

# ssh without passwords, useful for unattended automatic scp/rsync-over-ssh copies etc
# www.fduran.com

# Create public key without password in origin server:
ssh-keygen -t rsa

# if ssh target port is not 22, add it (ex: -p 2020) in ssh-copy-id after 'ssh':
# nano /usr/bin/ssh-copy-id

# Upload public key to remote target server:
# using password (you need in the target server's sshd config file: ChallengeResponseAuthentication Yes )
ssh-copy-id -i /home/user/.ssh/id_rsa.pub remote_ip

# or add public key of origin (do in origin server: ssh-keygen -y) in target's /home/user/.ssh/authorized_keys

# test:
ssh -p 2020 remote_ip