Operation Manual – 802.1x-System Guard
H3C S3100 Series Ethernet Switches Chapter 1 802.1x Configuration
1-8
z Upon receiving the packet from the switch, the RADIUS server retrieves the user
name from the packet, finds the corresponding password by matching the user
name in its database, encrypts the password using a randomly-generated key,
and sends the key to the switch through an RADIUS access-challenge packet.
The switch then sends the key to the 802.1x client.
z Upon receiving the key (encapsulated in an EAP-request/MD5 challenge packet)
from the switch, the client program encrypts the password of the supplicant
system with the key and sends the encrypted password (contained in an
EAP-response/MD5 challenge packet) to the RADIUS server through the switch.
(Normally, the encryption is irreversible.)
z The RADIUS server compares the received encrypted password (contained in a
RADIUS access-request packet) with the locally-encrypted password. If the two
match, it will then send feedbacks (through a RADIUS access-accept packet and
an EAP-success packet) to the switch to indicate that the supplicant system is
authenticated.
z The switch changes the state of the corresponding port to accepted state to allow
the supplicant system to access the network.
z The supplicant system can also terminate the authenticated state by sending
EAPoL-Logoff packets to the switch. The switch then changes the port state from
accepted to rejected.
 Note:
In EAP relay mode, packets are not modified during transmission. Therefore if one of
the four ways are used (that is, PEAP, EAP-TLS, EAP-TTLS or EAP-MD5) to
authenticate, ensure that the authenticating ways used on the supplicant system and
the RADIUS server are the same. However for the switch, you can simply enable the
EAP relay mode by using the dot1x authentication-method eap command.
II. EAP terminating mode
In this mode, EAP packet transmission is terminated at authenticator systems and the
EAP packets are converted to RADIUS packets. Authentication and accounting are
carried out through RADIUS protocol.
In this mode, PAP or CHAP is employed between the switch and the RADIUS server.
Figure 1-9 illustrates the authentication procedure (assuming that CHAP is employed
between the switch and the RADIUS server).
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