How To Monitor TCP/IP Ports in Use (194938)

MORE INFORMATION

1. Create a new Standard EXE project. Form1 is created by default.
2. Add 1 Timer, 2 Labels, 1 Listbox, 1 TextBox and 2 CommandButton controls to Form1. Position Label1 above Text1 and Label2 above List1.
3. Set the Sorted property of List1 to True.
4. Add the following code to the General Declarations section of Form1:

         Option Explicit
   
         Const PortsChecked = 200
   
         Private Sub Command1_Click()
            Timer1.Enabled = True
            Timer1.Interval = 1000
         End Sub
   
         Private Sub Command2_Click()
            Timer1.Interval = 0
            Timer1.Enabled = False
         End Sub
   
         Private Sub Timer1_Timer()
            Dim X As Integer
   
            List1.Clear
            For X = 1 To PortsChecked
               DoEvents
               Text1.Text = X
               WinSock1.LocalPort = X
               On Error Resume Next
               WinSock1.Listen  ' If we get an error, the port is busy.
               If Err.Number = 10048 Then
                  List1.AddItem X  ' Log Active port # to list box.
                  Err.Number = 0
               End If
   
               WinSock1.Close
            Next X
         End Sub
   
         Private Sub Form_Load()
            Label1.Caption = "Checking Port #"
            Label2.Caption = "Ports In Use"
            Command1.Caption = "Start"
            Command2.Caption = "End"
            Text1.Locked = True
         End Sub
   					

5. Run the program. If, for example, you have an active DCOM connection, you should see 135 displayed in the ListBox.
   
   To change the number of ports checked, modify the constant PortsChecked. To change the amount of time between samples modify the constant TimerInt.