18.4.6 Ensure 'MSS: (KeepAliveTime) How often keep-alive packets are sent in milliseconds' is set to 'Enabled: 300,000 or 5 minutes (recommended)'

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Information

This value controls how often TCP attempts to verify that an idle connection is still intact by sending a keep-alive packet. If the remote computer is still reachable, it acknowledges the keep-alive packet.

The recommended state for this setting is: Enabled: 300,000 or 5 minutes (recommended).

Rationale:

An attacker who is able to connect to network applications could establish numerous connections to cause a DoS condition.

Impact:

Keep-alive packets are not sent by default by Windows. However, some applications may configure the TCP stack flag that requests keep-alive packets. For such configurations, you can lower this value from the default setting of two hours to five minutes to disconnect inactive sessions more quickly.

Solution

To establish the recommended configuration, set the following Device Configuration Policy to Enabled: 300,000 or 5 minutes (recommended):

To access the Device Configuration Policy from the Intune Home page:

Click Devices

Click Configuration profiles

Click Create profile

Select the platform (Windows 10 and later)

Select the profile (Administrative Templates)

Click Create

Enter a Name

Click Next

Configure the following Setting

Path: Computer Configuration/MSS (Legacy)
Setting Name: MSS: (KeepAliveTime) How often keep-alive packets are sent in milliseconds
Configuration: Enabled: 300,000 or 5 minutes (recommended)

Select OK

Continue through the Wizard to complete the creation of the profile (profile assignments, applicability etc.)

Note: More than one configuration setting from each of the Configuration profiles (ex: Administrative Templates, Custom etc.) can be added to each Device Configuration Policy.

Default Value:

7,200,000 milliseconds or 120 minutes.