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18.6.9.1 Ensure 'Turn on Mapper I/O (LLTDIO) driver' is set to 'Disabled'

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Information

This policy setting changes the operational behavior of the Mapper I/O network protocol driver.

LLTDIO allows a computer to discover the topology of a network it's connected to. It also allows a computer to initiate Quality-of-Service requests such as bandwidth estimation and network health analysis.

The recommended state for this setting is: Disabled.

To help protect from potentially discovering and connecting to unauthorized devices, this setting should be disabled to prevent responding to network traffic for network topology discovery.

Solution

To establish the recommended configuration via GP, set the following UI path to Disabled :

Computer Configuration\Policies\Administrative Templates\Network\Link-Layer Topology Discovery\Turn on Mapper I/O (LLTDIO) driver

Note: This Group Policy path is provided by the Group Policy template LinkLayerTopologyDiscovery.admx/adml that is included with all versions of the Microsoft Windows Administrative Templates.

Impact:

Some real-time applications could have issues with short network disconnections. For more information visit: Network disconnection after configuring the LLTDIO and RSPNDR group policy objects - Windows Server | Microsoft Learn https://learn.microsoft.com/en-us/troubleshoot/windows-server/group-policy/network-disconnection-after-configuring-lltdio-rspndr-gpos.

See Also

https://workbench.cisecurity.org/benchmarks/25708

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, CSCv7|5.1

Plugin: Windows

Control ID: f7f7bbc3ed3cc146a203af61f37ec40144f2d8dfc4b43bddff4629ac6d06f053