Imports System.Net.Sockets
Imports System.IO
Imports System.Net
Imports System.Text
Public Class Form1
    Dim stream As NetworkStream
    Dim streamw As StreamWriter
    Dim server As TcpListener
    Dim client As New TcpClient
    Dim ipendpoint As IPEndPoint = New IPEndPoint(IPAddress.Any, 1581)
    Dim t As New Threading.Thread(AddressOf Main)
    Dim datastring As String = Nothing
    Public bbsdata As String = Nothing
    Public bbsdataprevious As String = Nothing
 
    Sub Main()
        Try
            server = New TcpListener(ipendpoint)
            server.Start()
            client = server.AcceptTcpClient
            client.ReceiveBufferSize = 1024
            Dim ns As NetworkStream = client.GetStream
            Dim data(client.ReceiveBufferSize) As Byte
            datastring = ""
            '---read incoming stream; Read() is a blocking call---
            Dim numBytesRead As Integer = ns.Read(data, 0, CInt( _
              client.ReceiveBufferSize))
            Dim z As Integer = 0
            While (numBytesRead <> 0)
                datastring = Encoding.ASCII.GetString(data, 0, numBytesRead)
                System.Diagnostics.Debug.WriteLine(Encoding.ASCII.GetString( _
                  data, 0, numBytesRead))
                SetTextBoxInfo(datastring)
            End While
        Catch
        End Try
    End Sub
    Public Sub SetTextBoxInfo(stringValue As String)
        If stringValue <> bbsdataprevious Then
            bbsdataprevious = stringValue
            Me.BeginInvoke(Sub() Me.TextBox2.Text = stringValue)
            datastring = ""
            client.Close()
            stream.Close()
        Else
        End If
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        If Button1.Text = "Start" Then
            t.Start()
            Button1.Text = "Stop"
        Else
            client.Close()
            stream.Close()
 
            Button1.Text = "Start"
        End If
    End Sub
End Class