File Blocking tab

Click the File Blocking tab in the policy to configure file download blocking for categories that users are allowed to access according to your settings in the Web Categories tab. This capability allows your organization to restrict access to particular files from websites in some or all permitted categories, based on true file type, file extension, or size. For example, you could permit the category Sports, but block multimedia (audio and video) files from sites in the Sports category.

Under Advanced Options, you can block the upload of executable files, or define file download size limits, or size limits per category.

The following file blocking options are available:

• True file type blocking: True file types are detected during security analysis. Several predefined groups of file types (for example, common image files) are included on the File Blocking tab for ease of selection.

  For example:

  1. The General Email category has the Allow access action, but file type blocking is enabled for multimedia files in the category.
  2. An end user attempts to download a file with a known extension (for example, “movie.mpeg”) or unknown extension (for example, “myfile.111”).
  3. If analysis determines that the file is classified as multimedia, the user receives a block page indicating that the download was blocked.
  4. If analysis determines that the file is not a multimedia file, the download request is permitted as long as the file is not categorized as another blocked file type.

  For more details, see Blocking by file type.

• File extension blocking: This blocks files based solely on file extensions that you specify.

  For example:

  1. The General Email category has the Allow access action, but the file extensions “.zip” and “.rar” are blocked for the category.
  2. An end user attempts to download a file with a file with a .zip extension (for example, “myfile.zip”).
  3. The user receives a block page indicating that the download was blocked by file extension, because the “.zip” file extension is specifically blocked for this category.

  For more details, see Blocking by file extension.

  Important: Archived/compressed files are not extracted to determine if the contents contain a file that should be blocked based on the type or extension. However, they are inspected for malware. Archived and compressed files can be blocked, if needed, in which case, all files contained in those archived files are blocked.
• Executable file upload blocking: This blocks the upload of any file identified as an executable. For more details, see Blocking executable file uploads.
• File size blocking: This blocks files based on the maximum size that you specify. You can block all files based on the following:
  • The file type and size.
  • The file type and size in a specific category or categories.
  • The file extension and size.
  • The file extension and size in a specific category or categories.
  • File size alone.
  • File size and category. See Block file downloads based on size, or size and category.