Access Authentication Control Commands - D-Link DGS-3700 Series Reference Manual

DGS-3700 Series Layer 2 Managed Gigabit Ethernet Switch CLI Reference Guide
A A
CCESS UTHENTICATION
Back to Section Header
The TACACS / XTACACS / TACACS+ / RADIUS commands allows secure access to the Switch using the
TACACS / XTACACS / TACACS+ / RADIUS protocols. When a 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+ / 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:
a) The server verifies the username and password, and the user is granted normal user privileges on the
Switch.
b) The server will not accept the username and password and the user is denied access to the Switch.
c) 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
C C
ONTROL OMMANDS
Page | 404