Unable to get MAC Address when installed on Web Server in ASP.Net

I want to capture MAC address of Client in Web Application and Store Data for that MAC address. How can I acheive this.

I have tried this but it capture Address of server where it is hosted.

 protected void Page_Load(object sender, EventArgs e)
        {
            lblMAC.Text = GetMACAddress();
        }

        public string GetMACAddress()
        {
            NetworkInterface[] nics = NetworkInterface.GetAllNetworkInterfaces();
            String sMacAddress = string.Empty;
            foreach (NetworkInterface adapter in nics)
            {
                if (sMacAddress == String.Empty)// only return MAC Address from first card  
                {
                    IPInterfaceProperties properties = adapter.GetIPProperties();
                    sMacAddress = adapter.GetPhysicalAddress().ToString();
                }
            } return sMacAddress;
        }