Execute the command (replace the IP address with the IP address of your target server):
dd if=/dev/hda | ssh username@127.0.0.1 "dd of=/directory_of_backups_on_ssh_server/backupfile.iso"
On Linux, to determine the device name for your source disk, use the following command:
sudo fdisk -l
On OpenSolaris or Solaris, to determine the device name for your source disk, use the following command:
pfexec format < /dev/null