how to block certain file format?

[seachen]

i found out that some of my users upload some ilegal music file in mp3 format.

it is hard for me to search all user data 1 by 1.

may i know how to block the mp3 format.

is it possible to make it user unable to upload file in *.mp3 format?

if possible, how do i make it?

 

[chatwizrd]

Are they uploading with file manager or ftp?

 

[seachen]

i think is with ftp. any way to prevent it?