Always On VPN Certificate Requirements for IKEv2

Always On VPN Certificate Requirements for IKEv2Internet Key Exchange version 2 (IKEv2) is one of the VPN protocols supported for Windows 10 Always On VPN deployments. When the VPN server is Windows Server 2016 with the Routing and Remote Access Service (RRAS) role configured, a computer certificate must first be installed on the server to support IKEv2. There are some unique requirements for this certificate, specifically regarding the subject name and Enhanced Key Usage (EKU) configuration. In addition, some deployment scenarios may require a certificate to be provisioned to the client to support IKEv2 VPN connections.

Server Certificate

The IKEv2 certificate on the VPN server must be issued by the organization’s internal private certification authority (CA). It must be installed in the Local Computer/Personal certificate store on the VPN server. The subject name on the certificate must match the public hostname used by VPN clients to connect to the server, not the server’s hostname. For example, if the VPN server’s hostname is VPN1 and the public FQDN is vpn.example.net, the subject field of the certificate must include vpn.example.net, as shown here.

Always On VPN Certificate Requirements for IKEv2

In addition, the certificate must include the Server Authentication EKU (1.3.6.1.5.5.7.3.1). Optionally, but recommended, the certificate should also include the IP security IKE intermediate EKU (1.3.6.1.5.5.8.2.2).

Always On VPN Certificate Requirements for IKEv2

Client Certificate

Client certificate requirements vary depending on the type of VPN tunnel and authentication method being used.

User Tunnel

No certificates are required on the client to support IKEv2 when using MSCHAPv2, EAP-MSCHAPv2, or Protected EAP (PEAP) with MSCHAPv2. However, if the option to verify the server’s identity by validating the certificate is selected when using PEAP, the client must have the certificates for the root CA and any subordinate CAs installed in its Trusted Root Certification and Intermediate Certificate Authorities certificate stores, respectively.

User Tunnel with Certificate Authentication

Using certificate authentication for the user tunnel is the recommended best practice for Always On VPN deployments. A client certificate must be installed in the Current User/Personal store to support PEAP authentication with smart card or certificate authentication. The certificate must include the Client Authentication EKU (1.3.6.1.5.5.7.3.2).

Always On VPN Certificate Requirements for IKEv2

Device Tunnel

A computer certificate must be installed in the Local Computer/Personal certificate store to support IKEv2 machine certificate authentication and the Always On VPN device tunnel. The certificate must include the Client Authentication EKU (1.3.6.1.5.5.7.3.2).

Always On VPN Certificate Requirements for IKEv2

More information about configuring the Always On VPN device tunnel can be found here.

Additional Information

Always On VPN with Trusted Platform Module (TPM) Certificates

Always On VPN Protocol Recommendations for Windows Server 2016 RRAS

Always On VPN and Windows Server RRAS

Always On VPN Training

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