ccna on udemy

ccna on udemy.EAP R /I d titChapter 20 Network Security and Monitoring .389.1 When a client has a need to access the network, open the IEEE802.lx client program and initiate a connection request (EAPOL-Start), which starts an authentication process.2 After the device side receives the data frame requesting authentication, it will send a request frame (EAP-Request/Identity) asking the client program to send the entered user name.3 The client program responds to the request from the device side and sends the user name information to the device side via an EAP-Response/Identity frame. The device side sends the data frame sent by the client to the authentication server for processing by encapsulating the RADIUSAccess-Request frame.4 After the RADIUS server receives the username information forwarded from the device side, it compares this information with the username in the database, finds the password information corresponding to this username, encrypts it with a randomly generated cryptographic word, and sends this cryptographic word to the device side via the RADIUSAccess-Challenge frame, which is forwarded to the client program.5 After the client program receives the EAP-Request/MD5Challenge frame containing the cryptographic word from the device side, it uses the cryptographic word to encrypt the password part, generates the EAP-Response/MD5 Challenge and passes it to the authentication server via the device side.6 The RADIUS server compares the received encrypted RADIUSAccess-Request frame with the local encrypted password information, and if they are the same, it considers the user as a legitimate user and feeds back the authentication passed message (RADIUS Access-Accept frame and EAP-Success frame).7 The device changes the port to the authorized state after receiving an authentication pass message, allowing the user to access the network through the port. During this period, the device side monitors the online status of the user by sending handshake packets to the client periodically. In other cases, if both handshake request packets are not answered by the client, the device side will let the user go offline to prevent the user from going offline for abnormal reasons that the device cannot sense.8 The client can also send an EAPOL-Logoff frame to the device side to actively request to go offline. The device side changes the port state from authorized to unauthorized and sends an EAP-Failure frame to the client.