Właśnie doczytałem, że nie chodzi Ci o zablokowanie listowania katalogu, więc ten pusty index.html -to nieważne.
Może Ci nie działać, bo w konfigu serwera jest ustawione, że nie możesz nadpisywać Allo czy deny, sprawdź w manualu coś o AllowOverride, np:
<Directory "/srv/www/htdocs">
# Possible values for the Options directive are "None", "All",
# or any combination of:
# Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews
#
# Note that "MultiViews" must be named explicitly --- "Options All"
# doesn't give it to you.
#
# The Options directive is both complicated and important. Please see
# http://httpd.apache.org/docs-2.2/mod/core.html#options
# for more information.
Options All
# AllowOverride controls what directives may be placed in .htaccess files.
# It can be "All", "None", or any combination of the keywords:
# Options FileInfo AuthConfig Limit
AllowOverride All
# Controls who can get stuff from this server.
Order allow,deny
Allow from all
</Directory>