c#中使用ARP获取mac地址

using System.Runtime.InteropServices;
using System.Text.RegularExpressions;
using System.Text; 

[DllImport("Iphlpapi.dll")]
private static unsafe extern int SendARP(Int32 dest,Int32 host,ref Int32 mac,ref Int32 length);

[DllImport("Ws2_32.dll")]
private static extern Int32 inet_addr(string ip); 

public string GetMACFromIP(string A_strIP)
{
string strRet = "Unknown";
string strIPPattern = @"^/d+/./d+/./d+/./d+$";
Regex objRex =new Regex(strIPPattern);
if(objRex.IsMatch(A_strIP) == true)
{
  Int32 intDest = inet_addr(A_strIP);
  Int32 [] arrMAC = new Int32[2];
  Int32 intLen = 6;
  int intResult = SendARP(intDest,0,ref arrMAC[0],ref intLen);
  if(intResult == 0)
    {
     Byte [] arrbyte = new Byte[8];
     arrbyte[5] = (Byte)(arrMAC[1] >> 8);
     arrbyte[4] = (Byte)arrMAC[1];
     arrbyte[3] = (Byte)(arrMAC[0] >> 24);
     arrbyte[2] = (Byte)(arrMAC[0] >> 16);
     arrbyte[1] = (Byte)(arrMAC[0] >> 8);
     arrbyte[0] = (Byte)arrMAC[0];
     StringBuilder strbMAC = new StringBuilder();
     for(int intIndex = 0 ;intIndex < 6;intIndex ++)
     {
     if(intIndex > 0) strbMAC.Append("-");
     strbMAC.Append(arrbyte[intIndex].ToString("X2"));
     }
     strRet = strbMAC.ToString();
     }//end of if // end of if objRex..

return strRet;

}