Upload a blank index.html file to the folder. The server will display that blank page instead of listing your files.
The exact date and time the server administrator last changed or uploaded the file. Intitle Index Of Mp3
If you want to explore further, let me know if you would like to look into: How to from directory listing Other advanced Google Dorking operators for research The history of early internet file sharing Share public link Upload a blank index
The days of massive, unprotected MP3 archives are numbered. Here is why: Intitle Index Of Mp3
However, the intent and actions of the user dictate the legality: