A small but effective tool (if you know the right way to use it..you might do wonders..)

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you need:

2 textboxes
1 listbox
3 commandbuttons
1 timer
1 winsock control
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Private Sub Command1_Click()
  Timer1.Enabled = True
End Sub

Private Sub Command2_Click()
  Timer1.Enabled = False
  Text2.Text = "0"
End Sub

Private Sub Command3_Click()
  List1.Clear
End Sub

Private Sub Timer1_Timer()
  On Error Resume Next
  Winsock1.Close
  Text2.Text = Int(Text2.Text) + 1
  Winsock1.RemoteHost = Text1.Text
  Winsock1.RemotePort = Text2.Text
  Winsock1.Connect
End Sub

Private Sub Winsock1_Connect()
 List1.AddItem Winsock1.RemotePort & " is open!"
End Sub

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Explanation:

text1 = IP to scan
text2 = starting port
list1 = list where all open ports are shown
command1 = start
command2 = stop and reset
command3 = clear port list
timer1 = will make the winsock control to try ports