2. Click the Access tab. The Access form appears.
3. To restrict access to o ne or more users or to a group of users, ente r previously defined user
or group names in th e Authorized Users/Groups field , with names separated by co mmas.
4. To deny access t o one or more users or grou ps, preface the user or group names with an
exclamationp oint (!).
5. Click Done.
6. Click apply changes.
Authenticationmethods and fallback mechanism
The following table provides a b rief description of the authent ication methods. W hen an
authenticati on method is configured to be performed by an authenticat ion serversu ch as
Kerberos, LDAP, RADIUS or TACACS+ , the user can get access denial if either th e
authenticati on serveris do wn or it does not authenticate. An auth entication fallback mechanism
can be defined in case th e first authenticatio n level fails. The follo wing table de scribes the
authenticati on methods and fallbac kmechanisms.
Authent ication Type Definition
None N o authentication.
Kerberos Authentication is perfor med using a Kerber os server.
Kerberos/Local Kerberosauthen ticationis tried fir st, switchingto Local if unsuccessful.
KerberosDownLocal Localauthentication isper formed only when the Kerbe ros server is down.
LDAP Authenticationis performed against an LDAP database using an LDAPserver.
LDAP/Local LDAP aut henticationis tried first, switching to Local if unsuccessful.
LDAPDownLocal Localauthent icationis perfor med only when the LDAP server is down.
Local Authent icationis perfor med locally.F or example, using the /etc/passwd file.
Local/Radius Authenticationisper formed locally first, switchingto Radius if unsuccessful.
Local/TACACS+ Authenticationisperform ed locallyfirst, switching to TAC ACS+ ifunsuccessful.
Local/NIS Authentication is performe d locallyfirst, switching to NIS if un successful.
NIS NISauthenticationis perfor med.
NIS/Local NIS au thenticationis tr ied first, switchingt o Local if unsuccessful.
Table 9.5: Expert - Authent ication Metho ds and Fallbac k Mechanisms
Chapter 9: Ports Men u and Forms 113