TACACS (Terminal Access Controller Access-Control System) is a network protocol that provides centralized authentication, authorization, and accounting services for network devices. By setting up a TACACS server, network administrators can control access to network resources and track user activity on the network. 

While TACACS can be a valuable tool for securing a network, it's essential to follow best practices to maximize security and minimize the risk of unauthorized access. Here are seven tips for using TACACS in a way that maximizes security.

1. Strong Passwords

Limit access to the TACACS server to authorized users only to protect against unauthorized access to your network during the authentication process. Use strong passwords for TACACS user accounts to prevent unauthorized access to the TACACS server and network resources. Use a mix of capital and lowercase letters, digits, and special characters to build a strong password.

2. Two-Factor Authentication 

By asking users to submit a second authentication method in addition to their password, two-factor authentication raises the level of security. This might be a one-time code texted or emailed to you, a tangible token like a security key, or both.

3. Role-Based Access Control

Implementing role-based access control (RBAC) can further restrict user access to certain parts of the network. These security measures ensure that only authorized users can access the TACACS server and the resources it protects.

4. Limit Privileges 

Users should only be able to view and work with the data or resources needed to do their job. Use TACACS to limit access to sensitive resources on the network. For example, you might grant access to the network's firewall only to a select group of users with a specific job function. This will help prevent unauthorized access to sensitive resources.

5. Monitor Activity

Use TACACS to track user activity on the network. This will help you identify any suspicious activity and take appropriate action. For example, if you notice that a user is accessing resources they don't usually have permission to access, you can investigate further to determine if there has been any unauthorized access.

6. Use Encryption

Use encrypted communication between the TACACS server and network devices. This helps prevent attackers from intercepting and viewing sensitive information transmitted between the TACACS server and the network devices. To enable encrypted communication, you can use Transport Layer Security (TLS) or Secure Sockets Layer (SSL) to secure the communication channel.

7. Patch Software

Keep the TACACS server software and the network's most recent security patches and updates installed on the devices. This will help ensure that the TACACS server and network devices are protected against known vulnerabilities and exploits. Be sure to regularly check for updates and apply them as soon as they are available.