File System Filter Drivers
A file system filter driver intercepts requests targeted at a file system or another file system filter driver. By intercepting the request before it reaches its intended target, the filter driver can extend or replace functionality provided by the original target of the request. Examples of file system filter drivers include anti-virus filters, backup agents, and encryption products. To develop file systems and file system filter drivers, use the IFS (Installable File System) Kit, which is provided with the Windows Driver Kit (WDK).
Filter Manager and Minifilters Basics. The Filter Manager is a file system filter driver provided by Microsoft that simplifies the development of third-party filter drivers and solves many of the problems with the existing legacy filter driver model, such as the ability to control load order through an assigned altitude. A filter driver developed to the Filter Manager model is called a minifilter. Every minifilter driver has an assigned altitude, which is a unique identifier that determines where the minifilter is loaded relative to other minifilters in the I/O stack. Altitudes are allocated and managed by Microsoft.
IFS Plugfest. The IFS Plugfest is an event for file system filter driver ISVs organized by the File System Filters team at Microsoft where the developers work with the ISVs to solve interoperability issues among various vendor solutions and the Filter Manager. It is also been a place where the ISV community is informed of the roadmap and informative sessions are presented on filter-driver related issues. More...
Filter Manager and MiniFilter Information
 | Filter Manager [177 KB] Overview of the new file system Filter Manager and minifilter model from Driver DevCon 2003. |
| Filter Manager Overview [147 KB] |
| Filter Manager Support in User Mode [56 KB] |
| Loading and Unloading Minifilters [84 KB] |
| Minifilter Generated IO's [52 KB] |
File System and Filter Driver Developer Resources
 | IFS Kit - Installable File System Kit Build environment, interfaces, samples, and documentation for developing kernel-mode file systems and file system filter drivers for Windows. |
 | Reparse Point Request Obtain an ID for a filter driver that uses reparse points. |
 | NT File System Drivers newsgroup Subscribe to the NTFSD newsgroup for details about developing file systems and filter drivers. |
| Training for IFS Developers OSR's "Developing File Systems for Windows" seminar explores developing file systems and file system filter drivers. |
 | Minifilter Altitude Allocation Request How to request allocation of an altitude from Microsoft. |
File System Filter Driver Information
Resources
WDK Resources on MSDN
| File System Minifile Drivers
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