Tacacs+ (Terminal Access Controller Access Plus) is a protocol that implements scalable AAA security solution for a network. You can install and configure Tacacs+ server to manage access to your network resources for every type of user (packet and char. mode).
Cisco has two products that implements tacacs+. One is Cisco secure and other is a unix tacacs+ deamon available free of cost but unsupported by cisco. Cisco secure is latest product with new feautres, easy GUI based configuration and its also supported by cisco.
For more information about tacacs+ read Cisco IOS security configuration guide available on CCO.
