Linux with winbind, disable local users while AD is available?

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http://serverfault.com – Routers and switches with RADIUS authentication can be configured such that login is disabled for locally configured users as long as the RADIUS server is available. If the RADIUS server becomes unavailable, they fall back to allowing login as a locally configured user. Is it possible to achieve the same effect with Linux machines using winbind to authenticate Active Directory users? I have a feeling it could be done with the right PAM configuration, but I'm not very far along on the PAM learning curve... (HowTos)