ssh-keygen / passwordless login for sh/php script

I am trying to create a backup script that will send the backup to an external server. I need to be able to do this securely also.

I'm running into a problem with sending the password for scp, and I know there is a way to create a public/private key for the two servers, but from what I've read the keys need to be created without a password. I'm not sure what the security risks are for doing this. Offhand it sounds dangerous.
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Of course it is more unsecure, however you can restrict the login for the key to specific commands
see e.g
or here


I strongly recommend you read this on how to setup public and private keys
Better still read this one....:

It shows you how to do the backups securely....and with a password to protect the keys (using agents). If you're going to do this, then you might as well do it properly.


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ShroderAuthor Commented:
Thank you!
I'll take a peek. :)
ShroderAuthor Commented:
I'm not sure what I'm doing wrong. The keys generated fine. Moved them to the remote server. Set the permissions. Primed the agent. Attached the agent. But it still asks me for a password.
Who's guide did you follow? also did you edit the sshd_config file
Here's a small howto.

From the client, type this command to generate the certificate. Leave all the question by default.
> ssh-keygen -t dsa

Take the file named from the client and put the content in the file /root/.ssh/authorized_keys2 on the server using this synthax:
from="client_ip", ssh-dss ...
Ensure that the file is 600 to make sure that no one can read it. The line "from=..." will allow the connection only from the provided IP.

Now, from the client, do a "ssh root@server_ip" and accept the authentication. It should only ask once.

You can replace the "root" username by any username you want. Just make sure it has a shell access.

If you have a problem connecting, you can try to put the line "PermitRootLogin without-password" in your /etc/ssh/sshd_config. If it still doesn't work, look at the log in /var/log/messages or /var/log/secure and post the content. It could help find the exact reason.
ShroderAuthor Commented:
ok. I can try that shortly.

One thing I noticed is the from contains something like from= should I change this to from= root@
Using the hostname or IP should not make any differences since the server will do a lookup for it.
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