What kind of physical device is an evil twin access point? what does the evil twin do after initial association when the victim client transmits? how are vpn s able to defeat evil twin attacks? explain in detail.

A PC such as a notebook computer.The evil twin gets the encrypted frame from the affected host,A VPN  encrypts a  frame with its own VPN key.

Explanation:

The evil twin after initial association when the victim client will establish a secure wireless connection with the victim client. The connection uses a key client-EF for encryption such that when the host transmits an encrypted frame it is transmitted to the evil twin. A VPN is an encrypted virtual private network used to access networks that are not trusted. The client encrypts a frame with a VPN key (Key Client-Server) which it shares with the server. The frame is further encrypted by the key it shares with the evil twin (Victim Client-ET) The evil twin will then receive a double encrypted frame. However, it will only be able to decrypt the Victim Client-ET key but not the VPN key hence it will not be able to read the message sent through the frame.