UNIX and Linux System Administration Handbook, 5th Edition

17	Single Sign-On

Both users and system administrators would like account information to magically propagate to all an environment’s computers so that a user can log in to any system with the same credentials. The common term for this feature is “single sign-on” (SSO), and the need for it is universal.

SSO involves two core security concepts: identity and authentication. A user identity is the abstract representation of an individual who needs access to a system or an application. It typically includes attributes such as a username, password, user ID, and email address. Authentication is the act of proving that an individual ...