TACACS+ Remote Authentication
The system takes the access class from the TACACS+ server. Access class is the class of service that restricts
Telnet access and packet sizes.
If you have configured remote authorization, the system ignores the access class you have configured for the
VTY line and gets this access class information from the TACACS+ server. The system must know the
username and password of the incoming user before it can fetch the access class from the server. A user,
therefore, at least sees the login prompt. If the access class denies the connection, the system closes the
Telnet session immediately. The following example demonstrates how to configure the access-class from a
TACACS+ server. This configuration ignores the configured access-class on the VTY line. If you have
configured a deny10 ACL on the TACACS+ server, the system downloads it and applies it. If the user is found
to be coming from the 10.0.0.0 subnet, the system also immediately closes the Telnet connection. Note, that
no matter where the user is coming from, they see the login prompt.
When configuring a TACACS+ server host, you can set different communication parameters, such as the key
password.
Example of Specifying a TACACS+ Server Host
Dell(conf)#
Dell(conf)#aaa authentication login tacacsmethod tacacs+
Dell(conf)#aaa authentication exec tacacsauthorization tacacs+
Dell(conf)#tacacs-server host 25.1.1.2 key Force
Dell(conf)#
Dell(conf)#line vty 0 9
Dell(config-line-vty)#login authentication tacacsmethod
Dell(config-line-vty)#end
Specifying a TACACS+ Server Host
To specify a TACACS+ server host and configure its communication parameters, use the following command.
• Enter the host name or IP address of the TACACS+ server host.
CONFIGURATION mode
tacacs-server host {hostname | ip-address} [port port-number] [timeout seconds]
[key key]
Configure the optional communication parameters for the specific host:
• port port-number: the range is from 0 to 65535. Enter a TCP port number. The default is 49.
• timeout seconds: the range is from 0 to 1000. Default is 10 seconds.
• key key: enter a string for the key. The key can be up to 42 characters long. This key must match a
key configured on the TACACS+ server host. This parameter must be the last parameter you
configure.
If you do not configure these optional parameters, the default global values are applied.
Example of Connecting with a TACACS+ Server Host
To specify multiple TACACS+ server hosts, configure the tacacs-server host command multiple times. If
you configure multiple TACACS+ server hosts, Dell Networking OS attempts to connect with them in the
order in which they were configured.
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