802.1X Authentication Procedure - H3C S5100-SI Operation Manual

Figure 1-6 The format of an EAP-message field
0
Type
The Message-authenticator field, whose format is shown in
unauthorized interception to access requesting packets during authentications using CHAP,
EAP, and so on. A packet with the EAP-message field must also have the
Message-authenticator field. Otherwise, the packet is regarded as invalid and is discarded.
Figure 1-7 The format of an Message-authenticator field

802.1x Authentication Procedure

A H3C S5100-SI/EI series Ethernet switch can authenticate supplicant systems in EAP
terminating mode or EAP relay mode.
EAP relay mode
This mode is defined in 802.1x. In this mode, EAP packets are encapsulated in higher level
protocol (such as EAPoR) packets to enable them to successfully reach the authentication
server. Normally, this mode requires that the RADIUS server support the two newly-added
fields: the EAP-message field (with a value of 79) and the Message-authenticator field
(with a value of 80).
Four authentication ways, namely EAP-MD5, EAP-TLS (transport layer security),
EAP-TTLS (tunneled transport layer security), and Protected Extensible Authentication
Protocol (PEAP), are available in the EAP relay mode.
EAP-MD5 authenticates the supplicant system. The RADIUS server sends MD5 keys
(contained in EAP-request/MD5 challenge packets) to the supplicant system, which in
turn encrypts the passwords using the MD5 keys.
EAP-TLS allows the supplicant system and the RADIUS server to check each other's
security certificate and authenticate each other's identity, guaranteeing that data is
transferred to the right destination and preventing data from being intercepted.
EAP-TTLS is a kind of extended EAP-TLS. EAP-TLS implements bidirectional
authentication between the client and authentication server. EAP-TTLS transmit
message using a tunnel established using TLS.
PEAP creates and uses TLS security channels to ensure data integrity and then
performs new EAP negotiations to verify supplicant systems.
Figure 1-8 describes the basic EAP-MD5 authentication procedure.
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EAP packets
Figure
1-6
1-7, is used to prevent