In today’s increasingly complex network environments, the need to secure administrative access to routers, switches, firewalls, and wireless controllers is critical. One of the most effective tools in a network security professional’s arsenal is TACACS+ (Terminal Access Controller Access-Control System Plus)—a protocol that provides centralized authentication, authorization, and accounting (AAA) for network devices.
But enabling TACACS+ is only the first step. To get the most security value out of it, organizations must apply a set of best practices to ensure it’s properly implemented, monitored, and scaled.
Below are key TACACS+ authentication best practices that every organization should follow to strengthen their infrastructure and minimize the risk of unauthorized access.
Use Unique User Accounts for Authentication
Avoid shared logins like admin or cisco. One of the primary benefits of TACACS+ is the ability to enforce individual user authentication, so that every action on the network is tied back to a specific person. This greatly improves accountability, traceability, and compliance posture.
Best practice: Integrate your TACACS+ implementation with an identity provider (IdP) like Azure AD, Okta, or LDAP to streamline account provisioning and deprovisioning.
Enforce Role-Based Access Control (RBAC)
TACACS+ allows you to assign users to different privilege levels (0–15 in Cisco IOS), enabling granular control over what each user can do on network devices.
- Level 1: Basic monitoring (e.g., help desk)
- Custom Levels (2–14): Task-specific roles (e.g., VLAN changes, interface config)
- Level 15: Full administrative control (senior engineers only)
Using privilege levels enforces least privilege access, which is critical for both security and operational efficiency.
3. Enable Full Command Accounting
TACACS+ doesn’t just authenticate users—it can also log every command they run. This is essential for:
- Auditing: Understanding who made changes to critical devices.
- Compliance: Proving enforcement of security policies for standards like HIPAA, PCI-DSS, and NIST.
- Incident Response: Quickly identifying malicious or mistaken configuration changes.
Best practice: Forward accounting logs to a centralized SIEM or syslog server for monitoring and retention.
4. Implement Multi-Factor Authentication (MFA) – or better yet, passwordless authentication
While TACACS+ itself doesn’t support MFA natively, many modern implementations allow for MFA integration through external identity providers. This is especially important for users with higher privilege levels.
By enforcing MFA, you add a critical second layer of defense—even if credentials are compromised.
Portnox Cloud TACACS+, for example, makes it easy to integrate with identity platforms to protect admin logins and implement certificate-based authentication.
5. Use Secure Communication Channels
Ensure all device connections use SSH instead of Telnet, and that the TACACS+ server itself is accessed over secure protocols like TLS/HTTPS for management.
Additionally:
- Place your TACACS+ server on a dedicated management VLAN
- Limit access using firewall rules or ACLs
- Consider high availability (HA) and backup options to avoid authentication outages
6. Simplify Policy Enforcement with Cloud-Based TACACS+
Traditional TACACS+ implementations often require manual configuration, local server maintenance, and siloed logs. That’s why many organizations are moving to cloud-native NAC platforms that offer built-in TACACS+ support.
Portnox Cloud TACACS+ delivers:
- Centralized user and role management
- Easy integration with modern identity systems
- Agentless enforcement on all managed and unmanaged network devices
- Real-time logging and command tracking
- Scalability across remote offices, data centers, and cloud environments
This simplifies the complexity of policy enforcement while strengthening your security posture across the board.
TACACS+ remains one of the most powerful and flexible tools for securing administrative access to network infrastructure. But like any tool, its effectiveness comes down to how it’s used.
By following best practices—centralizing identity, enforcing RBAC, enabling accounting, securing communication, and integrating MFA—you can transform TACACS+ from a simple login protocol into a cornerstone of your access security strategy.
And with solutions like Portnox Cloud TACACS+, you can implement these best practices faster, more securely, and at scale.