EAP (Extensible Authentication Protocol) is a general protocol for authentication that supports multiple authentication methods. EAP doesn't specify the type of authentication to use, but rather the authentication steps
EAP consists of 4 packets:
- EAP Request: Authenticator sends the request packe to the supplicant.
- EAP Response: The suplicant sends the response packet to the authenticator and uses a sequence number to identify each request.
- One response could be NAK which means the authentication method is not supported
- EAP Success: The authenticator sends the success packet to the supplicant after a succesful authentication
- EAP Failure: The authenticator sends the success packet to the supplicant after a failed authentication
The most common forms of EAP are:
It is very secure but requires client certificates so a PKI infrastructure should be in place.
It requires only server side certificate and it is supported by Cisco and Microsoft. There are 2 implementations: PEAP-GTC (generic implementation) and PEAP-MS-CHAPv2 (works with Microsoft AD)
It aims to provide as much security as EAP-TLS but without the need to manage certificates on client or server side.