Since ownCloud 4.5 it’s possible to configure additional user backends in ownCloud’s configuration file (config/config.php) using the following syntax:

'user_backends'=>array(
  array(
    'class'=>...,
    'arguments'=>array(...)
  )
)

Currently the “External user support” (user_external) app supports the provides the following user backends:

IMAP

provides authentication against IMAP servers

Class: OC_User_IMAP
Arguments: a mailbox string as defined here
Example:

'user_backends'=>array(
  array(
    'class'=>'OC_User_IMAP',
    'arguments'=>array('{imap.gmail.com:993/imap/ssl}INBOX')
  )
)

 

SMB

provides authentication against Samba servers

Class: OC_User_SMB
Arguments: the samba server to authenticate against
Example:

'user_backends'=>array(
  array(
    'class'=>'OC_User_SMP',
    'arguments'=>array('localhost')
  )
)

FTP

provides authentication against FTP servers

Class: OC_User_FTO
Arguments: the FTP server to authenticate against
Example:

'user_backends'=>array(
  array(
    'class'=>'OC_User_FTP',
    'arguments'=>array('localhost')
  )
)