Public MustInherit Class FtpClient
        Protected MustOverride Sub SetupSocket()
        Public Sub Login()
            SetupSocket()
        End Sub
    End Class
 
    Public Class PassiveClient
        Inherits FtpClient
        Protected Overrides Sub SetupSocket()
            'init Code 
        End Sub
    End Class
 
    Public Class SslClient
        Inherits FtpClient
        Protected Overrides Sub SetupSocket()
            'init Code 
        End Sub
    End Class

Those people who think they know everything are a great annoyance to those of us who do - Isaac Asimov