The original 802.11 standard has two choices in authenticating a client, Open Authentication and WEP (Wired Equivalent Privacy)
Open Authentication offers open access to a wireless network. The only requirement is that a 802.11 authentication request must be made before it attempts to associate with an access point.
Any 802.11 can authenticate to gain access to an open network, with no security challenge in order for access. All authentication does is validate that the client utilises the 802.11 protocol for joining a wireless network.
Creating an Open Authentication Network
To create a wireless network with open authentication on a Cisco wireless controller, create a wireless network and map it to the correct VLAN.
Next, go to the general tab and enter the name of the SSID and apply the appropriate controller interface. Remember to change the status to enabled.
Finally go the security tab and configure the wireless network security and user authentication settings. Select the Layer 2 tab and select None to enable open authentication.