VB.NET : Port Scanner

Imports System.Net.Sockets
Imports System.Net
Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.CheckForIllegalCrossThreadCalls = False 'Now you can Add items through a thread
        For i As Integer = NumericUpDown1.Value To NumericUpDown2.Value
            Dim tmpThread As New System.Threading.Thread(AddressOf ScanPort)
            tmpThread.IsBackground = True
            tmpThread.Start(i) 'i represents the current port 
        Next
    End Sub
    Private Sub ScanPort(ByVal port As Integer)
        Try 'Always put your code [or more complicated code] in a Try Catch Block :]
            Dim tmpClient As New TcpClient()
            Dim tmpEndPoint As New IPEndPoint(IPAddress.Parse(TextBox1.Text), port)
            tmpClient.Connect(tmpEndPoint)
            Threading.Thread.Sleep(50) '50 is the Timeout in ms.
            If tmpClient.Connected = True Then
                ListBox1.Items.Add("Open Port: " & port) 'If Connected then it will be an open port
            End If
        Catch ex As Exception
        End Try
    End Sub
End Class