Unixcop published a tutorial about how to turn off directory browsing on Apache and Nginx.

How to Turn Off directory browsing on Apache and Nginx

The directory content listing enabled by default when you install Apache web server, This may_be a desirable features in some scenarios, but it’s a potential security hole in others. It’s easy enough to turn this setting on or off for each website (virtual host) that you have set up. 

How to Turn Off directory browsing on Apache and Nginx - Unixcop the Unix / Linux the admins deams