Terminal Access Controller Access-Control System (TACACS+) is a remote authentication protocol used to communicate with an authentication server commonly used in UNIX networks. TACACS+ is a security application that provides centralized validation of users attempting to gain access to a router or network access server. TACACS+ services are maintained in a database on a TACACS+ daemon, typically on a UNIX workstation. The goal of TACACS+ is to provide a methodology for managing multiple network access points from a single management service.