This policy setting allows you to specify whether to require user authentication for remote connections to the RD Session Host server by using Network Level Authentication (NLA). This policy setting enhances security by requiring that user authentication occur earlier in the remote connection process. If you enable this policy setting, only client computers that support Network Level Authentication can connect to the RD Session Host server.

LAN Manager (LM) is a family of early Microsoft client/server software that allows users to link personal computers together on a single network. Network capabilities include transparent file and print sharing, user security features, and network administration tools. In Active Directory if the Kerberos protocol is not negotiated for some reason, Active Directory will use LM, NTLM, or NTLMv2.

This policy setting allows you to control the redirection of supported Plug and Play devices, such as Windows Portable Devices, to the remote computer in a Remote Desktop Services session. By default, Remote Desktop Services allows redirection of supported Plug and Play devices.

IP source routing is a mechanism that allows the sender to determine the IP route that a datagram should take through the network. An attacker could use source routed packets to obscure their identity and location. Source routing allows a computer that sends a packet to specify the route that the packet takes.

Maximum log size should be set to any kind of event logs, as part of your security policy. This configuration’s value is highly important for detecting attacks and investigating their source. Allocating insufficient storage space will lead to information loss of what happened in the network, therefore breaches could remain undetected.

NTLM is Microsoft’s old mythological authentication protocol. Although new and better authentication protocol has already been developed, NTLM is still very much in use. NTLM protocol has proven to have many flaws that result in potential vulnerabilities. One caution measure that can be taken is auditing and logging any NTLM traffic events.

Specifies whether to prevent the sharing of clipboard contents (clipboard redirection) between a remote computer and a client computer during a Remote Desktop Services session. By default, Remote Desktop Services allows clipboard redirection. If the status is set to Enabled, users cannot redirect clipboard data.