Windows Server Network Policy and Access Services (NPAS, more commonly called NPS) is a popular solution used in Always On VPN deployments to support Active Directory authentication for user-based VPN connections. NPS is integrated with Active Directory to perform certificate-based authentication. With additional configuration, NPS can apply specific settings to an individual connection by reading the properties of the user’s AD account.
Dial-In Properties
Administrators can allow or deny network access, assign a static IP address, or assign a static route on a per-user basis. This information is defined on the Dial-In tab of the user account in Active Directory Users and Computers (dsa.msc).
Register in AD
Registering the NPS server in Active Directory is strictly optional. It is not required to perform user authentication. However, administrators must register the NPS server in Active Directory to assign connection properties per user. Active Directory registration for NPS allows the NPS server to read the properties of individual Active Directory user accounts. Active Directory registration for NPS is accomplished in one of several ways.
NPS Management Console
On each NPS server, open the NPS management console (nps.msc), right-click the server, and choose Register server in Active Directory.
Command Line
Administrators can register the NPS server in Active Directory by opening an elevated command window and running the following command.
netsh.exe nps add registeredserver <domain> <host>
Where <domain> is the Active Directory domain where you want to add the NPS server to the RAS and IAS Servers security group, and <host> is the hostname of the NPS server to register.
For example:
netsh.exe nps add registeredserver lab.richardhicks.net nps1
ADUC
Registering an NPS server in Active Directory does nothing more than add the NPS server to the RAS and IAS Servers domain security group. Administrators can open ADUC and add NPS servers to the group directly if required.
Note: Registering an NPS server in Active Directory using the NPS console or the command line adds the NPS server to the RAS and IAS Servers group in the domain to which the NPS server belongs. If user accounts are in a different domain, NPS servers must also be added to the RAS and IAS Servers group in those domains.
NPS Policy
In addition to registering the NPS server in Active Directory, administrators must ensure that the option to Ignore user account dial-in properties on the Network Policy used for Always On VPN is not checked.
Additional Information
Always On VPN and NPS Server Load Balancing
