Linux does have directory server called OpenLDAP, but it requires good understanding and admin skills. Enterprise networks now have an alternative choice to Microsoft Active Directory (AD) servers, with the open source Samba project aiming for feature parity with the forthcoming release of version 4.
Every IT shop has a mix of Windows and Linux system. Sometime you need to authenticate your Linux desktop system against Microsoft Active Directory service. You can save time, effort and IT infrastructure by sharing authentication server. This article explains how to setup the Linux desktop computers with Active Directory using Samba and winbind.