LDAP policy backend

[chillout2k]

Facts:

• an own LDAP-schema extension (auxiliary) would be nice but not necessary
• It should be possible to reuse an existing/custom LDAP-schema (attribute mapping)
• custom search base is a must
• custom domain query (with macros like %d = domain) should be possible, like: (domain_name=%d)
• mandatory attributes:
  • tenant_id
  • dkim_enabled
  • dkim_alignment_enabled