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.