网络上有讲获得Mac address的方法有如下：

1. 发送ARP命令，利用返回的Mac Address缓冲区得到

2. 用NetworkInterface.GetAllNetworkInterfaces()获得所有网卡（包括虚拟网卡），从而获得相应的Mac address

3. 还有是从本机的注册表中获得：

    ManagementObjectSearcher managementObjectSearcher = new ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration");
    ManagementObjectCollection managementObjectCollection = managementObjectSearcher.Get();
    bool flag = false;
    using (ManagementObjectCollection.ManagementObjectEnumerator enumerator = managementObjectCollection.GetEnumerator())
    {
     while (enumerator.MoveNext())
     {

这三种方法第1，2种比较好，当本机有多块网卡，或虚拟网卡时，第三种在Win8下是不准确的。第1，2种都可以根据给定的参数IP值来准确定位对应的Mac Address.

第二种代码如下：

            string macAddress = "" ;
            NetworkInterface[] nics = NetworkInterface.GetAllNetworkInterfaces(); 
            foreach (NetworkInterface adapter in nics) 
            { 
                if (!adapter.GetPhysicalAddress().ToString().Equals("")) 
                { 
                    macAddress = adapter.GetPhysicalAddress().ToString(); 
                    for (int i = 1; i < 6; i++) 
                    { 
                        macAddress = macAddress.Insert(3 * i - 1, ":"); 
                    } 
                    break; 
                } 
            }

第一种方法如下：

        public static string GetMac(string p_Id)
        {
            IPAddress _Address;
            if (!IPAddress.TryParse(p_Id, out _Address)) return "";
            uint DestIP = System.BitConverter.ToUInt32(_Address.GetAddressBytes(), 0);
            ulong pMacAddr = 0;
            uint PhyAddrLen = 6;
            uint error_code = SendARP(DestIP, 0, ref pMacAddr, ref PhyAddrLen);
            byte[] _Bytes1 = BitConverter.GetBytes(pMacAddr);
            return BitConverter.ToString(_Bytes1, 0, 6);
        }

        [DllImport("Iphlpapi.dll")]
        public static extern uint SendARP(uint DestIP, uint SrcIP, ref ulong pMacAddr, ref uint PhyAddrLen);