for captive portal login
read here:
http://www.arubanetworks.com/techdocs/ArubaOS_61/ArubaOS_61_UG/Firewall_Roles.php
Re-authentication Interval (optional)
Time, in minutes, after which the client is required to reauthenticate. Enter a value between 0-4096. 0 disables reauthentication.
Default: 0 (disabled)
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for 802.1x
read here:
http://www.arubanetworks.com/techdocs/ArubaOS_60/UserGuide/802.1x.php
use re-auth option: (u can apply it on any
Reauthentication
Select this option to force the client to do a 802.1x re-authentication after the expiration of the default timer for re-authentication. The default value of the timer (Reauthentication Interval) is 24 hours. If the user fails to re-authenticate with valid credentials, the state of the user is cleared.
If derivation rules are used to classify 802.1x-authenticated users, then the Re-authentication timer per role overrides this setting.
Default: disabled