CGI script web frontend for BackupPC installed.
an extra config file has been added to your apache2 installation 
as well as an init script (http-backuppc.conf and apache2-backuppc2-backuppc)
Please have a look at the config file and modify it according to your
needs (Allow section in particular if you want to filter access)

To allow a user to access the web interface, create a flat-file :
# htpasswd2 -c /etc/BackupPC/htpasswd.users admin

Then to add or modify a user :
# htpasswd2 /etc/BackupPC/htpasswd.users $user