Private Function PortInUse(ByVal PortNumber As Integer) As _
   Boolean
*********************************************
PURPOSE: Determine if a TCP/IP port is in use
EXAMPLE:
    If PortInUse(21) Then
    MsgBox "The standard FTP port is in use on this machine"
    end if
**********************************************
Dim oSocket As Object
Dim bAns As Boolean

On Error Resume Next
Set oSocket = CreateObject("MSWinsock.Winsock.1")
   
    If Err.Number > 0 Then
        Err.Raise 30000, , "Could not create winsock object"
        Exit Function
    End If
   
Err.Clear

oSocket.LocalPort = PortNumber
oSocket.Listen

if we get this error, it means
port is busy
bAns = Err.Number = 10048
oSocket.Close
Set oSocket = Nothing
PortInUse = bAns

End Function