La migliore è la WPA usata PSK(definita da te) o generata (ci vuole un server che la rigeneri penso) non dovrebbe fare differenza (se non chè generata è difficile da una tipo "ciao" o simili...)
open e shared stanno ad indicare il metodo di autenticazione di una chiave wep...
Ti posto le info che trovi sulla pagina di help del router
"SSID Broadcast
Select Disabled if you would not like the SSID of your wireless network to be broadcasted by the DI-624. If this option is Disabled, the SSID of the DI-624 will not be seen by Site Survey utilities so your wireless clients will have to know the SSID of your DI-624 in order to connect to it.
Authentication
For added security on the wireless network, when enabling Encryption, the Authentication type can also be selected. If Shared Key is selected, the Access Point will not be seen on the wireless network except to the wireless clients that share the same WEP key with MAC Addresses allowed access as specified in Filter List. If Open System is chosen, only the wireless clients with the same WEP key will be able to communicate on the wireless network, but the Access Point will be visible to all devices on the network. The default value for Authentication is set to "Open System".
WEP
Wired Equivalent Protocol (WEP) is a wireless security protocol for Wireless Local Area Networks (WLAN). WEP provides security by encrypting the data that is sent over the WLAN. The DI-624 supports 2 levels of WEP Encryption: 64Bit encryption and 128Bit encryption. WEP is disabled by default. The WEP setting can be changed to fit an existing wireless network or to customize your wireless network.
Key Type
The Key Types that are supported by the DI-624 are HEX (Hexadecimal) and ASCII (American Standard Code for Information Interchange.) The Key Type can be changed to fit an existing wireless network or to customize your wireless network.
KEYS
Keys 1-4 allow you to easily change wireless encryption settings to maintain a secure network. Simply select the specific key to be used for encrypting wireless data on the network.
WPA
Wi-Fi Protected Access authorizes and authenticates users onto the wireless network. WPA uses stronger security than WEP and is based on a key that changes automatically at a regular interval. This mode requires a RADIUS server in the network.
WPA-PSK
Pre-Shared Key mode means that the wireless client and the router must have the same passphrase in order to establish the wireless connection. A RADIUS server is not required with PSK."
Non è un inglese troppo difficile.. spero.. altrimenti, armato di dizionario e buona pazienza puoi tradurlo! ^^
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