Originally posted by adapter ok thank u but do u think that this solution is more secure of my actual one?
Well I don't claim to be security expert, but I would say that using a private key/ shared key pair for passwordless logins is less secure than typing in your password manually. Unless you have your password on a sticky note posted on your monitor
But I still use for automated rsync server to server backups and feel that it is secure enough as long as it is used in conjunction with other appropriate security measures.
I'd disagree. It's definitely more secure, as what authenticates you (the key) is never actually transmitted over the network. You must use a passphrase on your key if you want it to be secure, but if you do, it should be quite a bit more secure than using a password.
You now need two separate things to log in to your machine; the passphrase and the key, wheras you only needed one before. When you log in, rather than sending your key across the network, there is a challenge process that happens that has your private key on your local machine encrypt some random data from the server. If the server can then decrypt that back to what it sent using your private key, it's a valid login.
The advantage is that a man in the middle attack of the encrypted channel won't reveal enough information for the attacker to log in as you, whereas with a password it would.