In addition to older and less-secure password-based authentication methods (which should be avoided), the built-in VPN solution uses Extensible Authentication Protocol (EAP) to provide secure authentication using both user name and password, and certificate-based methods. You can only configure EAP-based authentication if you select a built-in VPN type (IKEv2, L2TP, PPTP or Automatic).
Windows supports a number of EAP authentication methods.
Method
Details
EAP-Microsoft Challenge Handshake Authentication Protocol version 2 (EAP-MSCHAPv2)
User name and password authentication
Winlogon credentials - can specify authentication with computer sign-in credentials
EAP-Transport Layer Security (EAP-TLS)
Supports the following types of certificate authentication
Certificate with keys in the software Key Storage Provider (KSP)
Certificate with keys in Trusted Platform Module (TPM) KSP
Smart card certficates
Windows Hello for Business certificate
Certificate filtering
Certificate filtering can be enabled to search for a particular certificate to use to authenticate with
Filtering can be Issuer-based or Enhanced Key Usage (EKU)-based
Server validation - with TLS, server validation can be toggled on or off
Server name - specify the server to validate
Server certificate - trusted root certificate to validate the server
Notification - specify if the user should get a notification asking whether to trust the server or not
Server validation - with PEAP, server validation can be toggled on or off
Server name - specify the server to validate
Server certificate - trusted root certificate to validate the server
Notification - specify if the user should get a notification asking whether to trust the server or not
Inner method - the outer method creates a secure tunnel inside while the inner method is used to complete the authentication
EAP-MSCHAPv2
EAP-TLS
Fast Reconnect: reduces the delay between an authentication request by a client and the response by the Network Policy Server (NPS) or other Remote Authentication Dial-in User Service (RADIUS) server. This reduces resource requirements for both client and server, and minimizes the number of times that users are prompted for credentials.
Cryptobinding: By deriving and exchanging values from the PEAP phase 1 key material (Tunnel Key) and from the PEAP phase 2 inner EAP method key material (Inner Session Key), it is possible to prove that the two authentications terminate at the same two entities (PEAP peer and PEAP server). This process, termed "cryptobinding", is used to protect the PEAP negotiation against "Man in the Middle" attacks.
Tunneled Transport Layer Security (TTLS)
Inner method
Non-EAP
Password Authentication Protocol (PAP)
CHAP
MSCHAP
MSCHAPv2
EAP
MSCHAPv2
TLS
Server validation: in TTLS, the server must be validated. The following can be configured:
Server name
Trusted root certificate for server certificate
Whether there should be a server validation notification
For a UWP VPN plug-in, the app vendor controls the authentication method to be used. The following credential types can be used:
The following image shows the field for EAP XML in a Microsoft Intune VPN profile. The EAP XML field only appears when you select a built-in connection type (automatic, IKEv2, L2TP, PPTP).
