WMI
using System.Management;
//get infomation of MAC
//get infomation of MAC
myinfo1= new ManagementClass("WIN32_NetworkAdapterConfiguration");
my=myinfo1.GetInstances();
foreach( ManagementObject one in my)
{
if((bool)one["IPEnabled"]==true)
{
info=one["MacAddress"].ToString();
this.textBox2.Text=info;
break;
}