Authentication from multi source in Plone 4?

How can I authent开发者_开发问答icate user from multiple source altogether ? For example local (ZODB or ldap), facebook and openid.

Do I need to write a new PAS plugin ? Or We can achieve this the existed products ?

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There's no need to do anything.

The authentication is already done from all sources at the same time. For ex, if you configure the ldap plugin, Plone's local users can still do login.