3Com 10014299 manual Request Authenticator Adopts 16-byte random code

532CHAPTER 38: CONFIGURING AAA AND RADIUS PROTOCOL

Figure 167 RADIUS packet structure

Code

Identifier

Length

Authenticator

Attribute

The Identifier field is used to match request packets and response requests. It varies with the Attribute field and the valid received response packets, but remains unchanged during retransmission. The Authenticator field (16 bytes) is used to authenticate the request transmitted by the RADIUS server, and it can also be used on the password hidden algorithm. There are two kinds of Authenticator packets:

■Request Authenticator: Adopts 16-byte random code.

■Response Authenticator: Is the result of performing the MD5 algorithm on Code, Identifier, Request Authenticator, Length, Attribute and shared-key.

The Code field decides the type of RADIUS packets, as shown in Table 597.

Table 597 The Type of Packets Decided by Code Field

Code	Packet type	Explanation of the packet
1	Access-Request	Direction: Client -> Server.
		The Client transmits the user information to Server to decide
		whether or not to allow the user to access.
		The packet must contain User-Name attribute, and may
		contain such attributes as NAS-IP-Address, User-Password or
		NAS-Port.
2	Access-Accept	Direction: Server->Client.
		If all the Attribute values in the Access-Request packets are
		acceptable (i.e., the authentication is successful), this type of
		packet can be transmitted.
3	Access-Reject	Direction: Server->Client.
		If none of the Attribute values in the Access-Request packet is
		acceptable (i.e., the authentication has failed), this type of
		packet can be transmitted.
4	Accounting-Request	Direction: Client->Server.
		Client transmits the user information to Server and request
		accounting. The Acct-Status-Type attribute in this packet
		differentiates accounting start request and accounting stop
		request. The attributes in this packet is almost the same as
		those in Access-Request packet.
5	Accounting-Response	Direction: Server->Client.
		Server informs Client that the Accounting-Request packet is
		received and the accounting information is correctly recorded.
		The packet includes inbound/outbound bytes,
		inbound/outbound packets and session time on the interface.

The Attribute field carries special AAA information, and provides the configuration details of request and response packets in the triplet form of type, length, and value. Table 598 lists the explanation of Attribute fields defined by RFC.