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mechanism, retransmission mechanism, and slave server mechanism. Figure 4 shows the RADIUS
packet format.
Figure 4
RADIUS packet format
Descriptions of the fields are as follows:
1.
The Code field (1-byte long) indicates the type of the RADIUS packet. Table 1 shows
potential values and their meanings.
Table 1
Main values of the Code field
Code Packet
type
Description
1 Access-Request
From the client to the server. A packet of this type carries
user information for the server to authenticate the user. It
must contain the User-Name attribute and can optionally
contain the attributes of NAS-IP-Address, User-Password,
and NAS-Port.
2 Access-Accept
From the server to the client: If all the attribute values
carried in the Access-Request are acceptable (the
authentication succeeds), the server sends an Access-
Accept response.
3 Access-Reject
From the server to the client. If any attribute value
carried in the Access-Request is unacceptable, the server
rejects the user and sends an Access-Reject response.
4 Accounting-Request
From the client to the server: A packet of this type carries
user information for the server to start/stop accounting
for the user. It contains the Acct-Status-Type attribute,
which indicates whether the server is requested to start
the accounting or to end the accounting.
5 Accounting-Response
From the server to the client: The server sends the client
a packet to notify client that it has received the
Accounting-Request and has started recording the
accounting information.
2.
The Identifier field (1-byte long) matches request packets and response packets and detects
retransmitted request packets. The request and response packets of the same type have the
same identifier.
