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WLAN security configuration
The terms AP and fat AP in this document refer to A-MSR900 and A-MSR20- 1 X routers with IEEE 802.1 1b/g
and A-MSR series routers installed with a SIC WLAN module.
The wireless security capabilities incorporated in 802.1 1 are inadequate for protecting networks containing
sensitive information. They do a fairly good job for defending against the general public, but not good
hackers. As a result, there is a need to implement advanced security mechanisms beyond the capabilities of
802.1 1.
Authentication modes
To secure wireless links, the wireless clients must be authenticated before accessing the AP, and only wireless
clients passing the authentication can be associated with the AP. 802.1 1 links define two authentication
mechanisms: open system authentication and shared key authentication.
Open system authentication
Open system authentication is the default authentication algorithm. This is the simplest of the available
authentication algorithms. Essentially it is a null authentication algorithm. Any client that requests
authentication with this algorithm can be authenticated. Open system authentication is not required to be
successful as an AP may decline to authenticate the client. Open system authentication involves a two-step
authentication process. In the first step, the wireless client sends a request for authentication. In the second
step, the AP determines whether the wireless client passes the authentication and returns the result to the
client.
Figure 11 Open system authentication process
Client
Authentication request
Authentication response
Shared key authentication
The following figure shows a shared key authentication process. The two parties have the same shared key
configured.
The client sends an authentication request to the AP.
1.
The AP randomly generates a challenge and sends it to the client.
2.
The client uses the shared key to encrypt the challenge and sends it to the AP.
3.
The AP uses the shared key to encrypt the challenge and compares the result with that received from
4.
the client. If they are identical, the client passes the authentication. If not, the authentication fails.
AP
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