FileZilla transfers file through CONNECT method and bypasses below rule: acl FTP proto FTP acl PUT method PUT http_access deny FTP PUT squid.conf says: # acl aclname req_mime_type mime-type1 ... # # regex match against the mime type of the request generated # # by the client. Can be used to detect file upload or some # # types HTTP tunneling requests. # # NOTE: This does NOT match the reply. You cannot use this # # to match the returned file type. Is there any way to detect FileZilla FTP upload? If there's no other way, please let me know free Win32 ftp client program having "HTTP Proxy with FTP support" feature.