Wikipedia
BackupPC is a free disk-to-disk backup software suite with a web-based frontend. The cross-platform server will run on any Linux, Solaris, or UNIX-based server. No client is necessary, as the server is itself a client for several protocols that are handled by other services native to the client OS. In 2007, BackupPC was mentioned as one of the three most well known open-source backup software, even though it is one of the tools that are "so amazing, but unfortunately, if no one ever talks about them, many folks never hear of them"
Data deduplication reduces the disk space needed to store the backups in the disk pool. It is possible to use it as D2D2T solution, if the archive function of BackupPC is used to back up the disk pool to tape. BackupPC is not a block-level backup system like Ghost4Linux but performs file-based backup and restore. Thus it is not suitable for backup of disk images or raw disk partitions.
BackupPC incorporates a Server Message Block (SMB) client that can be used to back up network shares of computers running Windows. Paradoxically, under such a setup the BackupPC server can be located behind a NAT'd firewall while the Windows machine operates over a public IP address. While this may not be advisable for SMB traffic, it is more useful for web servers running Secure Shell (SSH) with GNU tar and rsync available, as it allows the BackupPC server to be stored in a subnet separate from the web server's DMZ.
It is published under the GNU General Public License.