My UWP VPN app add to username another symbols

Question

I create vpn profile from my UWP app.

If I try to connect to a server, I see at server logs received EAP identity '?\test'.

My username credential transform from "test" to "?\test"

Sorry for my English :)

public async void connect()
        {
            string eapConfig = @"<EapHostConfig xmlns=""http://www.microsoft.com/provisioning/EapHostConfig""><EapMethod><Type xmlns=""http://www.microsoft.com/provisioning/EapCommon"">26</Type><VendorId xmlns=""http://www.microsoft.com/provisioning/EapCommon"">0</VendorId><VendorType xmlns=""http://www.microsoft.com/provisioning/EapCommon"">0</VendorType><AuthorId xmlns=""http://www.microsoft.com/provisioning/EapCommon"">0</AuthorId></EapMethod><Config xmlns=""http://www.microsoft.com/provisioning/EapHostConfig""><Eap xmlns=""http://www.microsoft.com/provisioning/BaseEapConnectionPropertiesV1""><Type>26</Type><EapType xmlns=""http://www.microsoft.com/provisioning/MsChapV2ConnectionPropertiesV1""><UseWinLogonCredentials>false</UseWinLogonCredentials></EapType></Eap></Config></EapHostConfig>";

            VpnNativeProfile profile = new VpnNativeProfile
            {
                ProfileName = "TestUWP",
                AlwaysOn = false,
                NativeProtocolType = VpnNativeProtocolType.IpsecIkev2,
                RememberCredentials = true,
                RequireVpnClientAppUI = true,
                RoutingPolicyType = VpnRoutingPolicyType.ForceAllTrafficOverVpn,
                TunnelAuthenticationMethod = VpnAuthenticationMethod.Eap,
                UserAuthenticationMethod = VpnAuthenticationMethod.Eap,
                EapConfiguration = eapConfig
            };
            profile.Servers.Add("test.test.com");

            var profileStatus = await windowsVpnManager.AddProfileFromObjectAsync(profile);
            Debug.Print($"profile status -> {profileStatus}\n");


            PasswordCredential credential = new PasswordCredential { UserName = "test", Password = "test123" };

            var connectionStatus = await windowsVpnManager.ConnectProfileWithPasswordCredentialAsync(profile, credential);

            Debug.Print($"connection status -> {connectionStatus}\n");
        }

Answer 1

I've just asked the VPN developer team about this. The short answer is that the code adds the "?" because that's what the Microsoft RRAS server is expecting to see. The Windows IKEv2 was designed to work as part of the entire Domain solution. Each user is part of some "Domain" -- in some companies, everyone is in one domain; in others people get put into different domains.

The VPN developers think that because you're providing a user name ("test") without a domain name, a dummy domain name ("?") is added along with the needed backslash.