Daily Backup Using RSYNC

Using these steps your system backup automatically using rsync.

Step 1: Generate a Public Key using ssh-keygen at Host machine.

root@home:~# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
19:44:5f:1c:92:27:26:25:9b:13:df:dc:89:71:f0:c1 root@home

Step 2: Insert the key to authorized_key at host machine
root@home:~# cd /root/.ssh/
root@home:/root/.ssh# ls
id_rsa id_rsa.pub known_hosts
root@home:/root/.ssh# cp id_rsa.pub authorized_keys
root@home:/root/.ssh# ls
authorized_keys id_rsa id_rsa.pub known_hosts
root@home:/root/.ssh#

Step 3: Copy the ~/.ssh/authorized_keys file to the remote(back) machine
As the backup machine storing backup of several machines, authorized_keys file already exits, just copy the line whole string from ~/.ssh/authorized_keys from host machine and append to the file at backup machine.

Step 4: Change permission of ~/.ssh/authorized_keys file, if needed.

#chmod 644 /.ssh/authorized_keys

Step 5: Create a script e.g backup and place in /etc/cron.daily/ and change permission to execute.

This will backup the whole machine, you can add specific files instead of /

#!/bin/sh
#
# backup
#
DEST=root@backup.yourdomain.com
RSYNC="rsync -aqP --delete -e ssh"

dpkg -l | cut -d' ' -f3 > /etc/deblist

$RSYNC / $DEST:/var/backups/.

(Optional)Step6: Change the time of /cron.daily from /etc/crontab file
So that your machines start syncing different time.

/etc/crontab
# m h dom mon dow user command
17 * * * * root cd / && run-parts --report /etc/cron.hourly
30 4 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6 * * 7 root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6 1 * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
#

Readings
http://www.scrounge.org/linux/rsync.html