What Is MIME Filtering


SecureSchool, ISBossBox, and LibraryDoor have the ability to filter content based on their "MIME Type".  This article aims to explain what exactly this filtering means and does.

Applies To

SecureSchool, ISBossBox, LibraryDoor

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SecureSchool's MIME Type filtering, located under "Content Filtering" -> "MIME Filtering" controls what types of files are allowed through the filter.  Sometimes File Extension Blocking is not adequate, which is why this feature exists.

A file can have any extension and still retain its original properties.  For example, if you rename a file from "MyWordFile.doc" to "MyWordFile.foo" and tell Microsoft Word to open the file, it will do so easily without asking you for any help identifying the file.  This is because most files have special markers in them identifying what type of file it really is.  There are many standardized MIME types, "image/jpeg" for example, for a jpeg / jpg image.  It's not required for a file to have a MIME type specified in it, but most common file types do.

The reason this level of filtering is important is to catch websites trying to slip forbidden content through.  For example, you may block the "mp3" file extension to prevent users from downloading music, but if a site has the file as "SomeSong.mus", the user simply has to rename the file to "SomeSong.mp3" after it downloads, and they got exactly what they wanted.  With MIME Filtering on, the MIME filter will catch that it's really a "audio/mpeg" file type, and will block it (if you've chosen to).

Mike Filtering is controlled by Filter Set, just like all other filtering features in SecureSchool.  To block a MIME Type, go to "Content Filtering" -> "MIME Filtering" -> select a Filter Set -> find the MIME type you want to block, and click on "Clock to Block MIME Type".

Alternatively, you can block groups of common MIME types from the Task Center.  For example, to block all MIME types related to streaming media, go to "Task Center" -> "Anti-Streaming Media Center", and check the box for "Block Streaming Media MIME Types".  This will block all MIME types related to streaming media.  If you want to selectively allow some streaming media and not other, you must uncheck this box and turn each MIME type on individually.



Posted 13 Years Ago, Updated 13 Years Ago