How to monitor and capture data in a specific port in VB / 2005

Posted: July 8, 2008 in Non Insteon Programming
Tags: , , , , , , , , , , ,

In one of my  previous post I had shown how to capture the Caller Id info of a modem.  So what do I do this the information??

In my case I notify all the PC in the house a particular caller / number is ringing by sending data on a specific port.  So they know who it is before picking up or even looking at the phone for the caller Id info. Below is the code on how to monitor a port for data.

In this case it will open and monitor port 81.  Since there is no event for the TCPListener Im using the VB timer control, then check the port for any pending data ever 1000ms , if data is pending it will read it and show it in a pop-up in the icon tray. 🙂

To keep it simple here, and Not shown here, I actually FTP back via code (Will setup another post for this) to the server and grab the image of the person which is then displayed on the client on another window.

Like all code here, is all in VB 2005. For setup: Note that for this  to work you do need to open port 81 (TCP) on the client.

Just create a basic form with the following controls (All are default names)

A Notify object called “NotifyIcon1”
A timer object called “Timer1”

‘—————— setup my Import variables, some may not be needed.

Imports System.Web
Imports System.Net
Imports System.Net.Sockets
Imports System.IO
Imports System
Imports System.ComponentModel
Imports System.Threading
Imports Microsoft.VisualBasic

'----------------------- Here is the main class which loads the form.
Public Class Form1
    Public WithEvents OpenPort As TcpListener '--------- I setup the TCPListner object, There really isnt no events for it so I have to check using a timer.

'--------- GET THE CLIENT ip FROM THE ENVIRONMENT This will return ina array the IP of the client in the case of XP the first ip(0) should be fine, in the case
'--------- vista you have to search for it. I just looked for the first octet to be the same as my internal network.

    Public ip() As System.Net.IPAddress = System.Net.Dns.GetHostEntry(Environment.MachineName).AddressList
    Public IPAdresstxt As String

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        'ip(0) = IPAddress.Parse(Microsoft.VisualBasic.Interaction.Command()) '---- Un-comment for XP

'------- for Vista the first item of the array can be anything, so I loop thru the values looking for the same network of my home network
        Dim ip_count As Integer
        or ip_count = 0 To ip.Length - 1
            If ip(ip_count).ToString.Contains("192") = True Then
                OpenPort = New TcpListener(ip(ip_count), 81)  '--------- Here we set the IP (My PC) and the port to monitor in this case 81
                IPAdresstxt = ip(ip_count).ToString
            End If

        OpenPort.Start() ' - Open and monitor
        NotifyIcon1.Visible = True
        NotifyIcon1.BalloonTipTitle = "Caller ID"
        NotifyIcon1.BalloonTipIcon = ToolTipIcon.Info
        NotifyIcon1.BalloonTipText = "Caller ID Running, window will close in 3 seconds"
        NotifyIcon1.ShowBalloonTip(2500)  '----------------- Hide my Icon popup after 2500 MS
        Me.Hide() '----------- This will hide my form and only leave the icon on the tray.  :)

    End Sub

'------------------ This is my main timer1 which is enabled and checked every 1 sec.
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        '-------------- CHECK PORT 81 IF GOT DATA
        If My.Computer.Network.IsAvailable = True Then  '----- If data is present then read data and pharse it.
            If OpenPort.Pending = True Then
                Dim bytes(1024) As Byte
                Dim data As String = Nothing
                Dim client As TcpClient = OpenPort.AcceptTcpClient()
                Dim stream As NetworkStream = client.GetStream()
                Dim i As Int32
                ' Loop to receive all the data sent by the client.
                i = stream.Read(bytes, 0, bytes.Length)
                While (i <> 0)
                    data = data + System.Text.Encoding.ASCII.GetString(bytes, 0, i)
                    data = data.ToUpper()
                    Dim msg As Byte() = System.Text.Encoding.ASCII.GetBytes(data)
                    i = stream.Read(bytes, 0, bytes.Length)
                End While

                data = LCase(data).Trim
                ShowCallerID(data)  '---------------------- Call the function to update the Notify-Icon
                Msgbox "Data received is"+data
         End If
        End If
    End Sub

'---------------------- Function to update the Notify-Icon
    Public Function ShowcallerID(number as Integer) As Boolean
        NotifyIcon1.BalloonTipText = "Incomming call from " + name + vbCrLf + " From # " + number.ToString
        IncommingCallWindow.txtName.Text = name
        If number.ToString.StartsWith("1") = True Then
            number = Val(Mid$(number, 2, number.ToString.Length - 1))
        End If

    End Function

End Class

  1. thermo_ll says:

    what is IncommingCallWindow.txtName.Text = name for how can i do it

    • lgarcia4617 says:

      Hi, that is the .. which will hold the response returned when data is collected from the serial port.

  2. […] Recent Comments beachbody on Insteon / X10 Home Automation…lgarcia4617 on Grabbing individual files via …george lewycky on Grabbing individual files via …lgarcia4617 on My first Insteon Motion Sensor…lgarcia4617 on How to monitor and capture dat… […]

  3. Ben says:

    It doesnt work online between two distant pc . I was wondering If is there a way to port forward with vb 2008 . Or open a port like you did but Online. Like a chat.

  4. vb2005AvdW says:


    I’m using your code to capture data from a tcp connection. It works great! Thanks!
    But now i have a problem, maybe you could help me a little bit.

    I use a TCPServer who receive a photo and a barcode. I can read the barcode so that’s oke.
    But i want to receive the photo also, the data wich is send by the client consist of 4 x 4 bytes of information (pic. name, pic, size etc.) about the picture(JPG). So the first thing i had to do is split the stream in data and image. And then i need to get the picture in a picturebox.

    Could you give me some hint or maybe code?

    I working with visual basic 2005.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s