Directory Services

Intro
Directory services are software programs that link directly into core databases to manage the identities and security of users on a network. They are crucial to many medium and large organisations. Directory services were part of an Open Systems Interconnection (OSI) initiative to get everyone in the industry to agree to common network standards to provide multi-vendor interoperability.

Usages:
There have been numerous forms of directory service implementations from different vendors. Systems developed before the advent of X.500 include:
 * Domain Name System: (DNS), the first directory service on the Internet, which is still used everywhere today.
 * Hesiod: was based on DNS and used at MIT's Project Athena.
 * Network Information Service: (NIS), originally named Yellow Pages (YP), was Sun Microsystems' implementation of a directory service for Unix network environments. It served a similar role as Hesiod.
 * NetInfo: was developed by NeXT in the late 1980s for NEXTSTEP. After being acquired by Apple, it was released as open source and used as the directory service for Mac OS X before being deprecated in favor of the LDAP-based Open Directory. Support for NetInfo was completely removed with the release of 10.5 Leopard.
 * Banyan VINES: was the first scalable directory services offering.
 * NT Domains: was developed by Microsoft to provide directory services for Windows machines prior to the release of the LDAP-based Active Directory in Windows 2000. Windows Vista continues to support NT Domains, but only after relaxing the minimum authentication protocols it supports.

Examples:
Active Directory is a very good example of this. It authenticates and authorizes all users and computers in a Windows domain type network—assigning and enforcing security policies for all computers and installing or updating software. For example, when a user logs into a computer that is part of a Windows domain, Active Directory checks the submitted password and determines whether the user is a system administrator or normal user.

Advantages:
·     Enables users to sign in using usernames and passwords that are used elsewhere.

·     Computer policies can be created to automatically update and secure workstations.

·     It is more secure than other directory services

Disadvantages:
·     Ongoing costs due to high maintenance

·     If the Active Directory goes down so does your network.