Authentication service (AS)

A service that usually runs on the same host as the Kerberos Key Distribution Center (KDC). The AS issues tickets for a requested service. The tickets are in turn given to users for access to the service. The AS answers requests from clients that do not send credentials with a request. The AS is generally used to gain access to the ticket-granting service (TGS) by issuing a ticket-granting ticket (TGT).