Single sign-on (SSO)

Single sign-on (SSO) is an authentication scheme that allows a user to log in with a single ID and password to any of several related, yet independent, software systems. It is often accomplished by using the Lightweight Directory Access Protocol (LDAP) and stored LDAP databases on (directory) servers. A simple version of single sign-on can be achieved over IP networks using cookies but only if the sites share a common DNS parent domain.For clarity, a distinction should be made between Directory Server Authentication and single sign-on: Directory Server Authentication refers to systems requiring authentication for each application but using the same credentials from a directory server, whereas single sign-on refers to systems where a single authentication provides access to multiple applications by passing the authentication token seamlessly to configured applications.