D-Link xStack DGS-3420 Series Reference Manual page 65

xStack® DGS-3420 Series Layer 2 Managed Stackable Gigabit Switch CLI Reference Guide
•
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+ / RADIUS security function to work properly, a
TACACS / XTACACS / TACACS+ / RADIUS 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+ / RADIUS 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 five 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.
Note: 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.
60