CISCO IOS in a Nutshell

Name

tacacs-server authenticate — global

Synopsis

tacacs-server authenticate connection [always] 
tacacs-server authenticate enable
tacacs-server authenticate slip [always] [access-lists]
no tacacs-server authenticate 

Configures

User authentication with TACACS and extended TACACS

Default

Disabled

Description

This command causes the router to contact the TACACS server and authenticate the user under the following conditions:

connection

When the user makes a TCP connection.

enable

When the user enters the enable command.

slip

When the user starts a SLIP or PPP connection.

For authenticating TCP or SLIP connections, the always keyword indicates that the router should always perform authentication even if the user is not logged in. Note that it is possible for a SLIP or PPP user to be connected, but not yet logged in. For authenticating SLIP connections, the access-lists keyword tells the router to check with the TACACS server to see if an access list needs to be installed for the user.

If you are using TACACS+, use the aaa authorization command instead of the tacacs-server authenticate command.