88 BigIron RX Series Configuration Guide
53-1002253-01
Configuring TACACS and TACACS+ security
4
Identifying the TACACS and TACACS+ servers
To use TACACS and TACACS+ servers to authenticate access to adevice, you must identify the 
servers to the device.
For example, to identify three TACACS and TACACS+ servers, enter commands such as the 
following.
BigIron RX(config)# tacacs-server host 207.94.6.161
BigIron RX(config)# tacacs-server host 207.94.6.191
BigIron RX(config)# tacacs-server host 207.94.6.122
Syntax: tacacs-server host <ip-addr> |ipv6<ipv6-addr> |<hostname> [auth-port <number>] 
The <ip-addr> |<hostname> parameter specifies the IP address or host name of the server. You 
can enter up to eight tacacs-server host commands to specify up to eight different servers.
To specify the server's host name instead of its IP address, you must first identify a DNS server using 
the ip dns server-address <ip-addr> command at the global CONFIG level.  
If you add multiple TACACS and TACACS+ authentication servers to the device, the device tries to 
reach them in the order you add them. For example, if you add three servers in the following order, 
the software tries the servers in the same order.
1. 207.94.6.161
2. 207.94.6.191
3. 207.94.6.122
You can remove a TACACS and TACACS+ server by entering no followed by the tacacs-server 
command.  For example, to remove 207.94.6.161, enter the following command.
BigIron RX(config)# no tacacs-server host 207.94.6.161
If you erase a tacacs-server command (by entering “no” followed by the command), make sure you 
also erase the aaa commands that specify TACACS and TACACS+ as an authentication method. 
(Refer to “Configuring authentication-method lists for TACACS and TACACS+” on page 90.) 
Otherwise, when you exit from the CONFIG mode or from a Telnet session, the system continues to 
believe it is TACACS and TACACS+ enabled and you will not be able to access the system.
The auth-port parameter specifies the UDP (for TACACS) or TCP (for TACACS+) port number of the 
authentication port on the server.  The default port number is 49.
Specifying different servers for individual AAA functions
In a TACACS+ configuration, you can designate a server to handle a specific AAA task.  For example, 
you can designate one TACACS+ server to handle authorization and another TACACS+ server to 
handle accounting. You can set the TACACS+ key for each server.
To specify different TACACS+ servers for authentication, authorization, and accounting.