• Diniz Martins

Cisco Nexus9000 | TACACS

Updated: Nov 19, 2020

This post describes how to configure the Terminal Access Controller Access Control System Plus (TACACS+) protocol on Cisco NX-OS devices.


About TACACS+:


The TACACS+ security protocol provides centralized validation of users attempting to gain access to a Cisco NX-OS device. TACACS+ services are maintained in a database on a TACACS+ daemon running, typically, on a UNIX or Windows NT workstation. You must have access to and must configure a TACACS+ server before the configured TACACS+ features on your Cisco NX-OS device are available.


TACACS+ provides for separate authentication, authorization, and accounting facilities. TACACS+ allows for a single access control server (the TACACS+ daemon) to provide each service—authentication, authorization, and accounting—independently. Each service can be tied into its own database to take advantage of other services available on that server or on the network, depending on the capabilities of the daemon.


The TACACS+ client/server protocol uses TCP (TCP port 49) for transport requirements. Cisco NX-OS devices provide centralized authentication using the TACACS+ protocol.


TACACS+ Advantages:


TACACS+ has the following advantages over RADIUS authentication:

  • Provides independent AAA facilities. For example, the Cisco NX-OS device can authorize access without authenticating.

  • Uses the TCP transport protocol to send data between the AAA client and server, making reliable transfers with a connection-oriented protocol.

  • Encrypts the entire protocol payload between the switch and the AAA server to ensure higher data confidentiality. The RADIUS protocol only encrypts passwords.


Commands script:

That’s all there is to it. With that guide NX-OS TACACS+ setup really isn’t difficult. Keep this guide in mind and perhaps create a template for future device setups.


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