Block downloading in Squid Proxy

In this tutorial i am going to block the downloading in squid proxy server.

#acl rule to block downloading
acl blockfiles urlpath_regex "/etc/squid/blockfiles"

#apply rule
http_access  allow limited_user !socialsites !blockfiles

Create file in server and paste the syntax
#vim /etc/squid/blockfiles
\.[Aa][Vv][Ii]$
\.[Mm][Pp][Gg]$
\.[Mm][Pp][Ee][Gg]$
\.[Mm][Pp]3$
\.[Mm][Pp]4$
\.3[Gg][Pp]$
\.mid
\.mp3$
\.3gp$
\.avi$
\.mp4$
\.mpg$
\.ram$
\.cab\?.*$
\.rm\?.*$
\.mp\?.*$
\.mpg\?.*$
\.mpeg\?.*$
\.mp3\?.*$
\.wmv\?.*$
\.wma\?.*$
\.mov\?.*$
\.avi\?.*$

#service squid reload