利用IP位置取得對方的Mac

要取得本機的MAC位置我們可以利用WMI或是.Net framework提供的相關功能來作，例如下面這兩篇

• 請問在 VB2005 中, 如何得知對方 MAC Address
  
• vb.net 2005如何獲取本機以下信息

那如果要得知遠端的MAC位址應該怎麼做，雖然可以利用arp的指令並將結果輸出到文字檔，但這樣有點麻煩，找了些參考資料後，我們可以用下面的程式碼來取得
首先是一些參考資料

• RtlMoveMemory
• SendARP Function
• How to get mac address with input ip address

下面是測試的程式碼

Private Const No_ERROR = 0

     _
    Private Shared Function inet_addr(ByVal s As String) As Integer
    End Function

     _
    Private Shared Function SendARP(ByVal DestIp As Integer, _
                                    ByVal ScrIP As Integer, _
                                    ByRef pMacAddr As Long, _
                                    ByRef PhyAddrLen As Long) As Integer
    End Function

     _
    Private Shared Sub CopyMemory(ByVal dst As Byte(), ByRef src As Long, ByVal bcount As Integer)
    End Sub

    Private Function GetRemoteMACAddress(ByVal sRemoteIP As String, ByRef sRemoteMacAddress As String) As Boolean
        Dim dwRemoteIp As Integer
        Dim pMacAddr As Long = 0
        Dim bpMacAddr() As Byte
        Dim PhyAddrLen As Long = 0
        Dim cnt As Long
        Dim tmp As String = ""

        dwRemoteIp = inet_addr(sRemoteIP)
        If dwRemoteIp <> 0 Then
            PhyAddrLen = 6
            If SendARP(dwRemoteIp, 0&, pMacAddr, PhyAddrLen) = No_ERROR Then
                If pMacAddr <> 0 And PhyAddrLen <> 0 Then
                    ReDim bpMacAddr(0 To PhyAddrLen - 1)
                    CopyMemory(bpMacAddr, pMacAddr, PhyAddrLen)
                    For cnt = 0 To PhyAddrLen - 1
                        tmp &= Hex(bpMacAddr(cnt) + 256).Substring(1, 2) & "-"
                    Next

                    If Len(tmp) > 0 Then
                        sRemoteMacAddress = tmp.Substring(0, tmp.Length - 1)
                        GetRemoteMACAddress = True
                    End If

                    Exit Function
                Else
                    GetRemoteMACAddress = False
                End If
            Else
                GetRemoteMACAddress = False
            End If
        Else
            GetRemoteMACAddress = False
        End If
    End Function