Imports System.Net.Sockets
 
Public Class Form1
    Dim sck_Server_TcpListener As TcpListener
    Private _clients As New List(Of TcpClient)
    Dim sck_Server_NWS As NetworkStream
    Dim bytes() As Byte
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As  _
      System.EventArgs) Handles MyBase.Load
        sck_Server_TcpListener = New TcpListener(System.Net.IPAddress.Parse(0), _
        44000)
        sck_Server_TcpListener.Start()
        sck_Server_TcpListener.BeginAcceptTcpClient(AddressOf OnConnect, New _
          Object)
    End Sub
    Private Sub OnConnect(ByVal data As System.IAsyncResult)
 
        'TcpClient holen der zu dieser Verbindung gehört.
        Dim client As TcpClient = sck_Server_TcpListener.EndAcceptTcpClient( _
          data)
        'In Liste merken
        _clients.Add(client)
 
 
        MsgBox("Connected")
        Dim info As New ReadDataState(client, bytes)
        'ReDim bytes(sck_ServerTcpClient.ReceiveBufferSize)
        Dim ns As NetworkStream = client.GetStream()
        ns.BeginRead(info.ReceiveBuffer, 0, info.ReceiveBuffer.Length, _
          AddressOf _
          OnDataArrival, info)
 
 
 
    End Sub
 
    Private Sub OnDataArrival(ByVal data As System.IAsyncResult)
        Dim clientdata As String = System.Text.Encoding.ASCII.GetString(bytes)
        Dim info As ReadDataState = CType(data.AsyncState, ReadDataState)
 
 
        Dim ns As NetworkStream = info.Client.GetStream()
        Dim numBytesRead = ns.EndRead(data)
 
        Dim message As String = System.Text.Encoding.ASCII.GetString( _
          info.ReceiveBuffer)
        MsgBox(message)
        ns.BeginRead(info.ReceiveBuffer, 0, info.ReceiveBuffer.Length, _
          AddressOf _
          OnDataArrival, info)
 
    End Sub
End Class
 
Public Class ReadDataState
    Public Sub New(ByVal client As TcpClient, ByVal bytes As Byte())
        Me.Client = client
        Me.ReceiveBuffer = bytes
    End Sub
    Public Client As TcpClient
    Public ReceiveBuffer As Byte()
End Class

 ns.BeginRead(info.ReceiveBuffer, 0, info.ReceiveBuffer.Length, AddressOf _
       OnDataArrival, info)