The reply_body_max_size directive prevents users from downloading very large files. The following configuration in Squid only allows download of size 15MB from IP range mentioned in the acl officelan. If the size is more it simply restricts the user with an error message. acl officelan src 192.168.1.0-192.168.1.54 reply_body_max_size 15 MB officelan Is there any way I can do something else instead of showing the error page to user when the size is more than 15MB. Something similar to the following: if ( reply_body_max_size > 15MB ) { // do this; } else { // do this; } Regards Supratik