This approach is very easy to bypass by any knowledgable hacker.
Since you said your WiFi is open, the only thing that needs to be done is fire up the aircrack-ng airdump and sniff, there I would see your MAC, in the clear. Then I could set my own to it or select any other mac I have seen connecting to for a longer while ,and use it and access your router and add my other mac on its whitelist.
Since you said your WiFi is open, the only thing that needs to be done is fire up the aircrack-ng airdump and sniff, there I would see your MAC, in the clear. Then I could set my own to it or select any other mac I have seen connecting to for a longer while ,and use it and access your router and add my other mac on its whitelist.