user logs in to the Switch or tries to access the administrator level privilege, he or she is prompted for a password. If TACACS / XTACACS / TACACS+ /

RADIUS authentication is enabled on the Switch, it will contact a TACACS / XTACACS / TACACS+ / RADIUS server to verify the user. If the user is verified, he

or she is granted access to the Switch.

There are currently three versions of the TACACS security protocol, each a separate entity.The Switch's software supports the following versions of TACACS:

•

TACACS (Terminal Access Controller Access Control System) —Provides password checking and authentication, and notification of user actions for

security purposes utilizing via one or more centralized TACACS servers, utilizing the UDP protocol for packet transmission.

•

Extended TACACS (XTACACS) — An extension of the TACACS protocol with the ability to provide more types of authentication requests and more

types of response codes than TACACS.This protocol also uses UDP to transmit packets.

•

TACACS+ (Terminal Access Controller Access Control System plus) — Provides detailed access control for authentication for network devices.

TACACS+ is facilitated through Authentication commands via one or more centralized servers.The TACACS+ protocol encrypts all traffic between

the Switch and the TACACS+ daemon, using the TCP protocol to ensure reliable delivery.

The Switch also supports the RADIUS protocol for authentication using the Access Authentication Control commands. RADIUS or Remote Authentication Dial

In User Server also uses a remote server for authentication and can be responsible for receiving user connection requests, authenticating the user and returning

all configuration information necessary for the client to deliver service through the user. RADIUS may be facilitated on this Switch using the commands listed in

this section.

In order for the TACACS / XTACACS / TACACS+ security function to work properly, a TACACS / XTACACS / TACACS+ server must be configured on a device

other than the Switch, called a server host and it must include usernames and passwords for authentication.When the user is prompted by the Switch to enter

usernames and passwords for authentication, the Switch contacts the TACACS / XTACACS / TACACS+ server to verify, and the server will respond with one of

three messages:

The server verifies the username and password, and the user is granted normal user privileges on the Switch.

The server will not accept the username and password and the user is denied access to the Switch.

The server doesn't respond to the verification query.At this point, the Switch receives the timeout from the server and then moves to the next

method of verification configured in the method list.

The switch has four built-in server groups, one for each of the TACACS, XTACACS,TACACS+ and RADIUS protocols.These built-in server groups are used to

authenticate users trying to access the Switch.The users will set server hosts in a preferable order in the built-in server group and when a user tries to gain

access to the Switch, the Switch will ask the first server host for authentication. If no authentication is made, the second server host in the list will be queried,

and so on.The built-in server group can only have hosts that are running the specified protocol. For example, the TACACS server group can only have TACACS

server hosts.

The administrator for the Switch may set up 6 different authentication techniques per user-defined method list (TACACS / XTACACS / TACACS+ / RADIUS /

local / none) for authentication.These techniques will be listed in an order preferable, and defined by the user for normal user authentication on the Switch, and

may contain up to eight authentication techniques.When a user attempts to access the Switch, the Switch will select the first technique listed for authentication.

If the first technique goes through its server hosts and no authentication is returned, the Switch will then go to the next technique listed in the server group for

authentication, until the authentication has been verified or denied, or the list is exhausted.

Please note that user granted access to the Switch will be granted normal user privileges on the Switch.To gain access to admin level privileges, the user must

enter the enable admin command and then enter a password, which was previously configured by the administrator of the Switch.

Note:

TACACS, XTACACS and TACACS+ are separate entities and are not compatible.The switch and the server must be configured exactly the

same, using the same protocol. (For example, if the Switch is set up for TACACS authentication, so must be the host server.).

The Access Authentication Control commands in the Command Line Interface (CLI) are listed (along with the appropriate parameters) in the following table.

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