Winlogon vs. Minlogon

Winlogon vs. Minlogon

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This isn’t meant to be an all inclusive description of the pros and cons of Winlogon vs. Minlogon. But there is some confusion of why they conflict in your configuration and why some features have behavioral problems with Minlogon.

If you want details on Winlogon and all its responsibilities check out this good description on MSDN, otherwise here’s the condensed description of Winlogon from MSDN:

Winlogon
A component of the Windows operating system that provides interactive logon support. Winlogon is designed around an interactive logon model that consists of three components: the Winlogon executable, a Graphical Identification and Authentication dynamic-link library (DLL) referred to as the GINA, and any number of network providers.

Winlogon.exe has *many* dependencies, hence greater footprint. Minlogon.exe is a custom version of winlogon.exe with certain functions removed in order to reduce it’s number of static dependencies to other features. We took into account the functionality required by many of our customers and weighed the pros/cons of what to remove without hobbling the system too much.

You can bet that if there’s a service that leverages interactive logon, it will *not* function properly under Minlogon.exe. Take Terminal Services for instance. Of course it needs to authenticate the remote user (by design for security purposes) therefore if you force a runtime with TS to also have Minlogon, TS will not operate properly.

It would be unrealistic in most cases to ask Windows features to take Design Change Requests to support Minlogon for the purpose of removing security features required by the other 900 Million Windows PCs out there. So we pick and choose our battles, adding back some functionality to address overwhelming customer requests when possible. Take for instance the classic issue in the newsgroup regarding a regression in some Power Management functionality in Minlogon.exe that was recently resolved.

At MEDC, a customer asked why TD kept complaining about Winlogon and Minlogon conflicting when he would disable or delete Winlogon but the next time he runs “Check Dependency” Winlogon returns and causes a conflict.

Right, that’s because there’s a feature component in the config that has a component dependency on Winlogon, if you want to force Minlogon just turn off “Autoresolve” in Target Designer and satisfy all other dependencies other than that one. If you’re not concerned about footprint and some superfluous features winding up in the runtime, another trick is to leave winlogon in the config, remove Minlogon, satisfy all other dependencies. But before you build, disable Winlogon and manually add Minlogon back to the config; don't run check dep again, just build it.

This way the configuration will build with Minlogon, the downside is that the configuration will have additional dependencies from the original Winlogon component left over that increase the surface attack area of the runtime as well as bloat the footprint.

There’s lots more to discuss about Minlogon, but that’ll have to be for later.

Post comments if you have specific Minlogon questions you'd like to see addressed in a future post.

- Andy

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