Appendix A WiMAX Security

•Authorization

Determines the network services available to authenticated users once they are connected to the network.

•Accounting

Keeps track of the client’s network activity.

RADIUS is a simple package exchange in which your base station acts as a message relay between the MS/SS and the network RADIUS server.

Types of RADIUS Messages

The following types of RADIUS messages are exchanged between the base station and the RADIUS server for user authentication:

•Access-Request

Sent by an base station requesting authentication.

•Access-Reject

Sent by a RADIUS server rejecting access.

•Access-Accept

Sent by a RADIUS server allowing access.

•Access-Challenge

Sent by a RADIUS server requesting more information in order to allow access. The base station sends a proper response from the user and then sends another Access-Request message.

The following types of RADIUS messages are exchanged between the base station and the RADIUS server for user accounting:

•Accounting-Request

Sent by the base station requesting accounting.

•Accounting-Response

Sent by the RADIUS server to indicate that it has started or stopped accounting.

In order to ensure network security, the access point and the RADIUS server use a shared secret key, which is a password they both know. The key is not sent over the network. In addition to the shared key, password information exchanged is also encrypted to protect the network from unauthorized access.

Diameter

Diameter (RFC 3588) is a type of AAA server that provides several improvements over RADIUS in efficiency, security, and support for roaming.

Security Association

The set of information about user authentication and data encryption between two computers is known as a security association (SA). In a WiMAX network, the process of security association has three stages.

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WiMAX Device Configuration User’s Guide