Juniper Networks EX2500 manual How TACACS+ Authentication Works

EX2500 Ethernet Switch Configuration Guide

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.

14„ Securing Access to the Switch