Kerberos V5 specifies a variety of name types ([RFC4120] section 7.5.8) for specifying the name of the server during a TGS request.

KILE uses service principal names (SPNs) (2) to identify servers in TGS-REQs. An SPN (2) is a single-string representation of a Kerberos principal name as defined in [RFC1964] section 2.1.1, that identifies the server. The Directory Service attribute servicePrincipalName, as defined in [MS-ADA3] section 2.252, is a multi-value attribute on a user or computer object that contains a list of SPNs (2), with each list item corresponding to a string representation of a Kerberos name that can be used to identify the server.

An SPN (2) is a string of the following format.

SPN = serviceclass "/" hostname [":"port] ["/" servicename]

 serviceclass = alphanum
 servicename = alphanum


Note: <alphanum> element is defined in [RFC2396] section 1.6.

An application can supply a name of the form "RestrictedKrbHost/<hostname>" when its callers have provided the hostname but not the correct SPN for the service. Applications MAY<24> use "RestrictedKrbHost/<hostname>" with awareness of the security considerations described in section 5.1.2. Applications calling GSS-API directly MUST provide a target name that is an SPN for their service applications for Kerberos authentication.