Using rsync in a cronjob when a password is needed

Question

Basically I have a bash script that fetches data from my server to perform a backup.

As it is now I have to start that script manually, enter the password, and then wait for it to finish.

I would like to set up a cronjob that handles the backup.

But I really don't know how to handle the password in a cronjob.

Also I can't use keys for this, because my provider does not provide the mechanisms I need to configure them.

I have SSH access to my home folder, but in my home folder I don't have write access except for the http(s)docs directory. So I cant create the necessary ~/.ssh/ directory and its contents for login via keys.

Answer 1

This is the command I use to backup to another machine:

rsync -av -e "ssh -i /root/ssh-rsync-valhalla-key" \
  --exclude lost+found \
  --delete-before \
  /mnt/backup/ \
  user@192.168.1.99:/cygdrive/r/\!Backups/Niflheim &

So you can use the -i to pass a keyfile to ssh. Of course, in your example, that means the keyfile itself will be sharable via HTTP if anybody ever figures out the filename.

Answer 2

Are you able to start a daemon and keep it running? You could run rsync in daemon mode if so.

Then on the client you would connect with an rsync:// url. For authorisation you could limit it to just your IP, I don't think there's an equivalent of SSH keys for it.

You need an rsyncd.conf, which can be anywhere, with something like:

[backup]
    path = /path/you/want/to/sync
    read only = true
    hosts allow = 1.2.3.4

Then start the daemon..

rsync --daemon --config=rsyncd.conf

And then you can try to sync from it:

rsync -av rsync://server.ip/backup /local/backup/dir