VB.Net Tutorial/Socket Network/Socket Port

Port scan

<source lang="vbnet">Imports System.Net.Sockets Imports System.Net Imports System.Threading Imports System.Text Public Class Tester

   Public Shared Sub Main
       Dim intPortStart As Integer = 1
       Dim intPortEnd As Integer = 10
       Dim lngLoop As Long
       For lngLoop = intPortStart To intPortEnd
           Dim myTcpClient As New TcpClient()
           Try
               myTcpClient.Connect("127.0.0.1", lngLoop)
               Console.WriteLine("Port " + lngLoop.ToString() + "started")
               myTcpClient.Close()
           Catch ex As SocketException
               Console.WriteLine("Port " + lngLoop.ToString() + " Closed" + ex.Message)
           End Try
       Next
   End Sub

End Class</source>

Port 1 ClosedNo connection could be made because the target machine actively refused it
Port 2 ClosedNo connection could be made because the target machine actively refused it
Port 3 ClosedNo connection could be made because the target machine actively refused it
Port 4 ClosedNo connection could be made because the target machine actively refused it
Port 5 ClosedNo connection could be made because the target machine actively refused it
^CTerminate batch job (Y/N)? n