Integrating some nodeBB communities?

[reaon]

What is the best way for integrating+authenticating two nodeBB forum?

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LDAP
http://en.wikipedia.org/wiki/Ldap
http://www.cmswiki.com/tiki-index.php?page=LDAP
Ex: http://drupal.org/project/ldap_integration

[julian]

Using a common OAuth2 provider would be your best bet