This guide describes the process to configure a Raspberry Pi Model B or Beaglebone Black to as a backup server to backup Windows or Linux machines using rsnapshot and then to sync those backups across multiple backup servers using rsync.

This guide was written for Linux and tested under Ubuntu 13.04.

Considerations

The backup drives used will be formated as ext4 which Windows cannot understand by default. You can install a Windows ext4 driver.

Required Hardware

Raspberry Pi Model B

• Raspberry Pi Model B
• 2GB+ SD Card
• 2 Amp USB Micro power adapter
• USB hard drive with external power supply
• Optionaly a case to protect the Raspberry Pi

Beaglebone Black

• Beaglebone Black
• 2GB+ micro SD card
• 2 Amp 5 Volt power adapter for the Beaglebone Black
• USB hard drive with external power supply
• Optionaly a case to protect the Beaglebone Black

Setup Guide

• Install Arch Linux ARM on your device: (Click the Installation tab and follow the instructions)
  • Raspberry Pi
  • Beaglebone Black
    • When you extract the bootloader tarball onto the FAT16 partition of the micro SD card you will get permission errors. This is fine, keep going.
    • Make sure you install Archlinux Arm onto the eMMC! If you only install it onto the micro SD card, the next time your Beaglebone Black looses power and powers back up it will boot back into its original operating system.
• Connect your device to a network using an ethernet cable and power it up. You will need to find the IP address it was assigned by the DHCP server on your network. The default hostname is alarm.

• Once you have the IP you need to ssh in to the device: $ ssh root@ipaddress ssh will issue a warning about the key fingerprint. Type yes and pressEnter. When prompted for the password type in root and hit Enter.

• Lets start by changing the root password: $ passwd root Type in your new password twice when prompted. Make sure to choose a strong password, this device will store all your backup data!

• Next lets change the hostname to something more meaningful: $ nano /etc/hostname Replace the current hostname of alarm with one of your choosing. Be descriptive.

  Press Ctrl+O, Enter, Ctrl+X to save and exit. The hostname will be updated the next time the device boots up.

• Update the system and install the packages we will need: $ pacman -Syu rsnapshot rsync sudo When asked if you want to proceed with the installation type Y and press Enter.

• Now lets add the backup user: $ useradd -m backup

• Create a password for the backup user: $ passwd backup The process is identical to when we changed the password for root.

• Create a sudo group and add the backup user to it: $ groupadd sudo $ usermod -aG sudo backup

• Next we need to allow users in the sudo group to use the sudo command: $ visudo This command will open the sudo configuration file in vi. Add the following line to the end of the file and save and exit: %sudo ALL=(ALL) ALL

• Now that we have a new user with sudo privilidges it is time to secure the ssh server. We will do this by disabling root login and password authentication. This means that you will only be able to login to your backup server using a ssh key. Make sure to keep it safe!

• You can either use an existing ssh key or generate a new one. If you need to generate a key this guide from Github can help.

• Now lets login as backup: $ su backup

• Next we need to copy the public key over to the backup server. To start with we need to create a .ssh directory in the backup users home directory: $ cd $ mkdir .ssh $ chmod 0700 .ssh

• To actually copy the public key we need to copy it from your local machine to the backup server. Exit the ssh session: $ exit

• Now you should be in a shell on your local machine. Navigate to the folder containing your public key and then use the following command to copy it over to your backup server. Replace ipaddress with the actual IP address of your backup server. Your public key might also have a different filename. $ scp id_rsa.pub backup@ipaddress:.ssh/authorized_keys

• That’s all it takes to enable ssh key login to your backup server. Lets make sure it works correctly. SSH into your backup server as the backup user. You should not be asked to enter a password! If you have to enter a password, something went wrong. $ ssh backup@ipaddress

• Once you have ssh key authentication working correctly, it is time to disable password authentication. This helps improve the security of the ssh server. Edit /etc/ssh/sshd_config: $ sudo nano /etc/ssh/sshd_config Add the following lines to the bottom of the file and save and exit: PermitRootLogin no PermitEmptyPasswords no PasswordAuthentication no

• Now we have to restart the ssh server to activate the changes. Your existing ssh session will survive the restart but if something went wrong you may not be able to establish new sessions. Do not close your current ssh session until you are sure the changes to the ssh server configuration were successful. Restart the ssh server: $ sudo service ssh restart

• Now open a new local shell and try to ssh into your backup server. If you can still login, you have successfully updated the sshd server settings.

• Restart?
• enable iptables?
• install fail2ban?
• configure usb drive
• configure rsnapshot

• configure rsync?

• http://spenserj.com/blog/2013/07/15/securing-a-linux-server/
• https://wiki.archlinux.org/index.php/Users_and_Groups
• https://help.github.com/articles/generating-ssh-keys#platform-linux