Directory services r standard feature of any medium to large corporate network. It is a type of database containing descriptives information of entries. Though dirs r most commonly used to store info about the users of an application / store group definitions / access controls /configuration parameters / user preferences. There r some tools for providing dir services for a network on Linux server like OpenLdap / Samba and also IBM released ver 5.1 for the same. See for more info:
www.daasi.de/staff/nk/thesis.pdf