windows-itpro-docs/windows/device-security/security-policy-settings/network-security-minimum-session-security-for-ntlm-ssp-based-including-secure-rpc-clients.md
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---
title: Network security Minimum session security for NTLM SSP based (including secure RPC) clients (Windows 10)
description: Describes the best practices, location, values, policy management and security considerations for the Network security Minimum session security for NTLM SSP based (including secure RPC) clients security policy setting.
ms.assetid: 89903de8-23d0-4e0f-9bef-c00cb7aebf00
ms.prod: w10
ms.mktglfcycl: deploy
ms.sitesec: library
ms.pagetype: security
author: brianlic-msft
ms.date: 07/27/2017
---
# Network security: Minimum session security for NTLM SSP based (including secure RPC) clients
**Applies to**
- Windows 10
Describes the best practices, location, values, policy management and security considerations for the **Network security: Minimum session security for NTLM SSP based (including secure RPC) clients** security policy setting.
## Reference
This policy setting allows a client device to require the negotiation of 128-bit encryption or NTLMv2 session security. These values are dependent on the **Network security: LAN Manager Authentication Level policy** setting value.
### Possible values
- Require NTLMv2 session security
The connection fails if the NTLMv2 protocol is not negotiated.
- Require 128-bit encryption
The connection fails if strong encryption (128-bit) is not negotiated.
### Best practices
Practices in setting this policy are dependent on your security requirements.
### Location
Computer Configuration\\Windows Settings\\Security Settings\\Local Policies\\Security Options
### Default values
The following table lists the actual and effective default values for this policy. Default values are also listed on the policys property page.
| Server type or GPO | Default value |
| - | - |
| Default Domain Policy | Not defined|
| Default Domain Controller Policy| Not defined|
| Stand-Alone Server Default Settings | Require 128-bit encryption|
| DC Effective Default Settings | Require 128-bit encryption|
| Member Server Effective Default Settings | Require 128-bit encryption|
| Client Computer Effective Default Settings | Require 128-bit encryption|
 
## Policy management
This section describes features and tools that are available to help you manage this policy.
### Restart requirement
None. Changes to this policy become effective without a device restart when they are saved locally or distributed through Group Policy.
### Policy conflicts
The settings for this security policy are dependent on the **Network security: LAN Manager Authentication Level policy** setting value. For info about this policy, see [Network security: LAN Manager authentication level](network-security-lan-manager-authentication-level.md).
## Security considerations
This section describes how an attacker might exploit a feature or its configuration, how to implement the countermeasure, and the possible negative consequences of countermeasure implementation.
### Vulnerability
Network traffic that uses the NTLM Security Support Provider (NTLM SSP) could be exposed such that an attacker who has gained access to the network can create man-in-the-middle attacks.
### Countermeasure
Enable all options that are available for the **Network security: Minimum session security for NTLM SSP based (including secure RPC) clients policy** setting.
### Potential impact
Client devices that enforce these settings cannot communicate with older servers that do not support them.
## Related topics
- [Security Options](security-options.md)