you can follow the steps:
https://doc.pfsense.org/index.php/SquidGuard_package#Block_download_by_Extension
and remember must click SAVE and go to "Proxy filter –> General Settings" click APPLY! ;)
[image: SG_blockextention.JPG]
[image: SG_blockextention.JPG_thumb]
[image: mp3_block_rule.png]
[image: mp3_block_rule.png_thumb]
[image: mp3_blocked_page.png]
[image: mp3_blocked_page.png_thumb]