scp without password

ssh-keygen -t rsa (leave the passphrase empty). It will generate two files:

Your identification has been saved in /home/xxx/.ssh/id_rsa.
Your public key has been saved in /home/xxx/.ssh/id_rsa.pub.

ssh-copy-id dest-user@dest-host (it will add the key to ~/.ssh/authorized_keys@dest-host)

scp /path/to/local/file dest-user@dest-host:/path/of/remote/dir/