I need login into my application using MFA after I login with user ID and password. We have DUO (for login to our servers).

Do you have any sample code (VB) which I can use in my application?

Namespace Forza
    Partial Public Class pagGoogleAuthenticator
        Inherits System.Web.UI.Page
 
        Private Property AuthenticationCode As String
            Get
                If ViewState("AuthenticationCode") IsNot Nothing Then Return ViewState("AuthenticationCode").ToString().Trim()
                Return String.Empty
            End Get
            Set(ByVal value As String)
                ViewState("AuthenticationCode") = value.Trim()
            End Set
        End Property
 
        Private ReadOnly Property AuthenticationTitle As String
            Get
                Return "Ankush"
            End Get
        End Property
 
        Private Property AuthenticationBarCodeImage As String
        Private Property AuthenticationManualCode As String
 
        Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
            If Not Page.IsPostBack Then
 
                lblResult.Text = String.Empty
                lblResult.Visible = False
                GenerateTwoFactorAuthentication()
                imgQrCode.ImageUrl = AuthenticationBarCodeImage
                lblManualSetupCode.Text = AuthenticationManualCode
                lblAccountName.Text = AuthenticationTitle
            End If
        End Sub
 
        Protected Sub btnValidate_Click(ByVal sender As Object, ByVal e As EventArgs)
            Dim pin As String = txtSecurityCode.Text.Trim()
            Dim status As Boolean = ValidateTwoFactorPIN(pin)
 
            If status Then
                lblResult.Visible = True
                lblResult.Text = "Code Successfully Verified."
            Else
                lblResult.Visible = True
                lblResult.Text = "Invalid Code."
            End If
        End Sub
 
        Public Function ValidateTwoFactorPIN(ByVal pin As String) As Boolean
            Dim tfa As TwoFactorAuthenticator = New TwoFactorAuthenticator()
            Return tfa.ValidateTwoFactorPIN(AuthenticationCode, pin)
        End Function
 
        Public Function GenerateTwoFactorAuthentication() As Boolean
            Dim guid As Guid = guid.NewGuid()
            Dim uniqueUserKey As String = Convert.ToString(guid).Replace("-", "").Substring(0, 10)
            AuthenticationCode = uniqueUserKey
            Dim result As Dictionary(Of String, String) = New Dictionary(Of String, String)()
            Dim tfa As TwoFactorAuthenticator = New TwoFactorAuthenticator()
            Dim setupInfo = tfa.GenerateSetupCode("Complio", AuthenticationTitle, AuthenticationCode, 300, 300)
 
            If setupInfo IsNot Nothing Then
                AuthenticationBarCodeImage = setupInfo.QrCodeSetupImageUrl
                AuthenticationManualCode = setupInfo.ManualEntryKey
                Return True
            End If
 
            Return False
        End Function
    End Class
End Namespace

But I still can't understand what I have to do else. I have login page where I put user name and password and what I have to add after.

This is my code behind from login page:

Dim loginUsername As String = Login1.UserName
Dim loginPassword As String = Login1.Password
 
Dim strSQL As String = "SELECT ID AS VAL, UserName, Password FROM tblUser WHERE (UserName = '" & funCheckChar(loginUsername)
strSQL &= "') AND (Password='" & funCheckChar(loginPassword) & "')"
 
intUserID = Val(ExecSQLReturnVal(strSQL))
 
 If intUserID > 0 Then
    e.Authenticated = True
 Else
     e.Authenticated = False
  End If

As I understand I have to add something here: 

If intUserID > 0 Then
    e.Authenticated = True
   ' add MFA here
Else
   e.Authenticated = False
End If

Thanks

Alex