How to get client machine MAC address

public static string GetClientIPAddress(System.Web.HttpRequest httpRequest)

{

    string OriginalIP = string.Empty; 

    string RemoteIP = string.Empty;



    OriginalIP = httpRequest.ServerVariables["HTTP_X_FORWARDED_FOR"]; //original IP will be updated by Proxy/Load Balancer.



    RemoteIP = httpRequest.ServerVariables["REMOTE_ADDR"]; //Proxy/Load Balancer IP or original IP if no proxy was used



    if (OriginalIP != null && OriginalIP.Trim().Length > 0)

    {

        return OriginalIP + "(" + RemoteIP + ")"; //Lets return both the IPs.

    }

    

    return RemoteIP;

}