Compromising open authentication wireless networks

In my long experience of penetration testing and red team activities, I've often discovered open networks, also known as guest networks. These networks are usually designed to provide guests with internet access without having a password set to authenticate the wireless network. However, often, captive portals are implemented to authenticate customers or guests to the internet.

Captive portals are authentication portals that pop up when any user connects to an open authentication wireless network to enter the credentials provided by the owner. These captive portals are usually implemented in coffee shops, hotels, colleges, and so on.

Myth

Now, network administrators usually implement MAC filtering on open authentication networks; for example, they will take the MAC of the guest's phone or laptop and apply a filter on it as a security measure. Or, if there is a captive portal implemented, organizations will create...