Concept Guide
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 congured remote authorization, the system ignores the access class you have congured 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 congure the access-class from a TACACS+ server.
This conguration ignores the congured access-class on the VTY line. If you have congured 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 conguring a TACACS+ server host, you can set dierent communication parameters, such as the key password.
Example of Specifying a TACACS+ Server Host
DellEMC(conf)#
DellEMC(conf)#aaa authentication login tacacsmethod tacacs+
DellEMC(conf)#aaa authentication exec tacacsauthorization tacacs+
DellEMC(conf)#tacacs-server host 25.1.1.2 key Force
DellEMC(conf)#
DellEMC(conf)#line vty 0 9
DellEMC(config-line-vty)#login authentication tacacsmethod
DellEMC(config-line-vty)#end
Specifying a TACACS+ Server Host
To specify a TACACS+ server host and congure 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]
Congure the optional communication parameters for the specic 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 congured on the
TACACS+ server host. This parameter must be the last parameter you congure.
If you do not congure these optional parameters, the default global values are applied.
Example of Connecting with a TACACS+ Server Host
To specify multiple TACACS+ server hosts, congure the tacacs-server host command multiple times. If you congure multiple
TACACS+ server hosts, Dell EMC Networking OS attempts to connect with them in the order in which they were congured.
To view the TACACS+ conguration, use the show running-config tacacs+ command in EXEC Privilege mode.
To delete a TACACS+ server host, use the no tacacs-server host {hostname | ip-address} command.
freebsd2# telnet 2200:2200:2200:2200:2200::2202
Trying 2200:2200:2200:2200:2200::2202...
Connected to 2200:2200:2200:2200:2200::2202.
Escape character is '^]'.
Login: admin
Password:
DellEMC#
834
Security