All Direct Access traffic must be routed through the internal network.

From Windows 8 Security Technical Implementation Guide

Part of Direct Access – Route Through Internal Network

Associated with IA controls: ECSC-1

SV-48443r1_rule All Direct Access traffic must be routed through the internal network.

Vulnerability discussion

Routing all Direct Access traffic through the internal network allows monitoring and prevents split tunneling.

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Configure the policy value for Computer Configuration -> Administrative Templates -> Network -> Network Connections -> "Route all traffic through the internal network" to "Enabled: Enabled State".

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