맥어드래스 가저오는 클래서 MAC Adress using System.Management;

 
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Threading;
using System.Management; // 어셈블리에서 참조를 걸어야 나옴

namespace WindowsApplication3
{
    public partial class MAINFM : Form
    {
        public MAINFM()
        {
            InitializeComponent();
            GetClientAdress();
        }

        public void GetClientAdress()
        {
            ManagementClass mc = new ManagementClass("Win32_NetworkAdapter");

   foreach (ManagementObject mo in mc.GetInstances())
            {
                string macAddr = mo["MACAddress"] as string;
                if (macAddr != null && macAddr.Trim() != "")
                   TextBox1.Text = macAddr.ToString();  // 텍스트 박스에 찍어주기
            }
        }
 }
}