How to detect the original MAC address after it has been spoofed?

Question

We are using the following code for retrieving active MAC address of a windows pc.

private static string macId()
{
    return identifier(\"Win32_NetworkAdapt         


        

Answer 1

I wish to give an alternative. I don't know if it really answer to 'a way to uniquely identify any computer'.
However, this method query the Win32_BIOS class in System.Management and return a string with high chances to be unique. (Waiting to be disavowed!!)

/// 

/// BIOS IDentifier
/// 
/// 
public static string BIOS_ID()
{
    return    GetFirstIdentifier("Win32_BIOS", "Manufacturer")
            + GetFirstIdentifier("Win32_BIOS", "SMBIOSBIOSVersion")
            + GetFirstIdentifier("Win32_BIOS", "IdentificationCode")
            + GetFirstIdentifier("Win32_BIOS", "SerialNumber")
            + GetFirstIdentifier("Win32_BIOS", "ReleaseDate")
            + GetFirstIdentifier("Win32_BIOS", "Version");
}

/// 

/// ManagementClass used to read the first specific properties
/// 
/// Object Class to query
/// Property to get info
/// 
private static string GetFirstIdentifier(string wmiClass, string wmiProperty)
{
    string result = string.Empty;
    ManagementClass mc = new System.Management.ManagementClass(wmiClass);
    ManagementObjectCollection moc = mc.GetInstances();
    foreach (ManagementObject mo in moc)
    {
        //Only get the first one
        if (string.IsNullOrEmpty(result))
        {
            try
            {
                if (mo[wmiProperty] != null) result = mo[wmiProperty].ToString();
                break;
            }
            catch
            {
            }
        }
    }
    return result.Trim();
}