Terminal Access Controller Access-Control System Plus (TACACS+) is a protocol developed by Cisco and released as an open standard beginning in 1993. Although derived from TACACS, TACACS+ is a separate protocol that handles authentication, authorization, and accounting (AAA) services.
tac_plus server is a major rewrite of the original Cisco source code.
For more information see http://www.shrubbery.net/tac_plus/, a reference manual for the configuration file is available at http://manpages.ubuntu.com/manpages/trusty/man5/tac_plus.conf.5.html .
An easier TACACS+ configuration can be done with
The appliance includes
to manage the password file