Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Try
            Dim ssl As String = "ssl://gateway.push.apple.com:2195"
            'Create a TCP/IP client socket
            Dim client2 As New TcpClient
            client2.Connect("gateway.push.apple.com", 2195)
            Dim b As Boolean = client2.Connected
            Dim sslStream2 As New SslStream(client2.GetStream, False, New RemoteCertificateValidationCallback(AddressOf ValidateServerCertificate), New LocalCertificateSelectionCallback(AddressOf SelectLocalCertificate))
sslStream2.AuthenticateAsClient(ssl)
Catch ex As AuthenticationException
            Throw New AuthenticationException(ex.ToString())
        Catch ex As Exception
        End Try
    End Sub

Public Shared Function SelectLocalCertificate(ByVal sender As Object, _
                                                  ByVal targetHost As String, _
                                                  ByVal localCertificates As X509CertificateCollection, _
                                                  ByVal remoteCertificate As X509Certificate, _
                                                  ByVal acceptableIssuers() As String) As X509Certificate
        Console.WriteLine("Client is selecting a local certificate.")

        If acceptableIssuers IsNot Nothing AndAlso acceptableIssuers.Length > 0 AndAlso localCertificates IsNot Nothing AndAlso localCertificates.Count > 0 Then
            'use the first certificate that is from an acceptable issuer.
            For Each certificate As X509Certificate In localCertificates
                Dim issuer As String = certificate.Issuer
                If Array.IndexOf(acceptableIssuers, issuer) <> -1 Then
                    Return certificate
                End If
            Next certificate
        End If
        If localCertificates IsNot Nothing AndAlso localCertificates.Count > 0 Then
            Return localCertificates(0)
        End If

        Return Nothing
    End Function