Which VMware Single Sign-On component handles STS authentication requests?

The Identity Management Service validates user credentials against configured identity sources such as Active Directory or LDAP when an STS authentication request is received, enabling the STS to issue a SAML security token upon successful validation.

The Administration Server manages SSO configuration and administrative operations but is not involved in processing live authentication requests.

The VMware Directory Service (vmdir) is an LDAP-compatible directory used to store SSO users and configuration data, but it does not directly handle or route STS authentication requests.

The Security Token Service issues SAML tokens as output after authentication succeeds; the actual processing of the incoming authentication request is performed by the Identity Management Service, not the STS itself.