Eap Authentication To The Network - Cisco M10-RM Software Manual

Understanding Authentication Types

EAP Authentication to the Network

This authentication type provides the highest level of security for your wireless network. By using the
Extensible Authentication Protocol (EAP) to interact with an EAP-compatible RADIUS server, the
access point helps a wireless client device and the RADIUS server to perform mutual authentication and
derive a dynamic unicast WEP key. The RADIUS server sends the WEP key to the access point, which
uses it for all unicast data signals that it sends to or receives from the client. The access point also
encrypts its broadcast WEP key (entered in the access point's WEP key slot 1) with the client's unicast
key and sends it to the client.
When you enable EAP on your access points and client devices, authentication to the network occurs in
the sequence shown in
Figure 11-3
Client
device
In Steps 1 through 9 in
use 802.1x and EAP to perform a mutual authentication through the access point. The RADIUS server
sends an authentication challenge to the client. The client uses a one-way encryption of the user-supplied
password to generate a response to the challenge and sends that response to the RADIUS server. Using
information from its user database, the RADIUS server creates its own response and compares that to
the response from the client. When the RADIUS server authenticates the client, the process repeats in
reverse, and the client authenticates the RADIUS server.
When mutual authentication is complete, the RADIUS server and the client determine a WEP key that
is unique to the client and provides the client with the appropriate level of network access, thereby
approximating the level of security in a wired switched segment to an individual desktop. The client
loads this key and prepares to use it for the logon session.
During the logon session, the RADIUS server encrypts and sends the WEP key, called a session key,
over the wired LAN to the access point. The access point encrypts its broadcast key with the session key
and sends the encrypted broadcast key to the client, which uses the session key to decrypt it. The client
and access point activate WEP and use the session and broadcast WEP keys for all communications
during the remainder of the session.
Cisco IOS Software Configuration Guide for Cisco Aironet Access Points
11-4
Figure 11-3:
Sequence for EAP Authentication
1. Authentication request
2. Identity request
3. Username
(relay to client)
5. Authentication response
(relay to client)
7. Authentication challenge
(relay to client)
9. Successful authentication
Figure 11-3, a wireless client device and a RADIUS server on the wired LAN
Wired LAN
Access point
or bridge
(relay to server)
4. Authentication challenge
(relay to server)
6. Authentication success
(relay to server)
8. Authentication response
(relay to server)
Chapter 11 Configuring Authentication Types
RADIUS Server
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