Detect Machines on a Network

P

Phreak

Regular
Joined
Jun 7, 2002
Messages
62
Location
Iowa, United States
Can anyone tell me how to quickly detect how many machines are on a particular subnet? Say I want to scan the network address 192.168.1.0 for all systems on that network/subnet. Right now I'm using a timer that goes off every 1ms. Here is the code I'm using:

Visual Basic: 
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        strFixedNetAddr = IP

        If iCounter < 255 Then
            bIPScan = True
            iCounter = iCounter + 1
            strFixedNetAddr = strFixedNetAddr & iCounter
            frmProgress.Show()
            frmProgress.ProgressBar1.Value = ((iCounter / 255) * 100)
            Try
                tcpClient.Connect(strFixedNetAddr, 27960)
            Catch ex As System.Exception
                If ex.Message.ToString = "No connection could be made because the target machine actively refused it" Then
                    arrIPsToSend(iIPCounter) = strFixedNetAddr
                    iIPCounter += 1
                Else
                    'no machine found so continue
                End If
                'MsgBox(arrIPsToSend(iIPCounter))
                lblFound.Text = iIPCounter
            End Try
        Else
            'we've sent 255 packets, and are done waiting.

            bIPScan = False
            iCounter = 0
            Timer1.Enabled = False
        End If

        btnSend.Enabled = True
    End Sub

Right now it's taking forever to detect the machines, what I really want to know is if a machine is NOT at a specific address, to just skip it right away and move on to the next address. Because now I'm waiting for it to timeout which takes forever.

Thanks.
 
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