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EX2500 Ethernet Switch Configuration Guide
14 Securing Access to the Switch
TACACS+ Authentication
The EX2500 switch supports authentication and authorization with networks using
the TACACS+ protocol. The EX2500 switch functions as the Network Access Server
(NAS) by interacting with the remote client and initiating authentication and
authorization sessions with the TACACS+ access server. The remote user is
defined as someone requiring management access to the EX2500 switch either
through a data port or a management port.
TACACS+ offers the following advantages over RADIUS:
TACACS+ uses TCP-based connection-oriented transport, whereas RADIUS is
UDP-based. TCP offers a connection-oriented transport, while UDP offers
best-effort delivery. RADIUS requires additional programmable variables such
as re-transmit attempts and time-outs to compensate for best-effort transport,
but it lacks the level of built-in support that a TCP transport offers.
TACACS+ offers full packet encryption, whereas RADIUS offers password-only
encryption in authentication requests.
TACACS+ separates authentication, authorization, and accounting.
How TACACS+ Authentication Works
TACACS+ works in much the same way as RADIUS authentication, as described on
page 11. The remote administrator connects to the switch and provides a
username and password.
1. Using Authentication/Authorization protocol, the switch sends a request to
authentication server.
2. The authentication server checks the request against the user ID database.
3. Using TACACS+ protocol, the authentication server instructs the switch to
grant or deny administrative access.
During a session, if additional authorization checking is needed, the switch checks
with a TACACS+ server to determine if the user is granted permission to use a
particular command.
TACACS+ Authentication Features in the EX2500 Switch
Authentication is the action of determining the identity of a user, and is generally
done when the user first attempts to log in to a device or gain access to its services.
The EX2500 switch supports ASCII inbound login to the device. PAP, CHAP, and
ARAP login methods; TACACS+ change password requests; and one-time
password authentication are not supported.
Authorization
Authorization is the action of determining a user’s privileges on the device, and
usually takes place after authentication.