TACACS+ (Terminal Access Controller Access Control System Plus) and RADIUS (Remote Authentication Dial-In User Service) are two commonly used network authentication protocols, which are used to manage user authentication and access control of network devices.
TACACS+ is a TCP/IP-based authentication protocol implemented by using a client/server architecture. It uses a separate authentication, authorization, and accounting (AAA) process to allow network devices (such as routers, switches) to establish a secure connection with a TACACS+ server. The specific implementation steps are simply divided into 4 steps.
| step1 | The device receives an authentication request from the user |
| step2 | Device sends authentication request to TACACS+ server |
| step3 | The TACACS+ server authenticates the user and compares the user name and password |
| step4 | If the authentication is successful, the server will return authorization information to the device, allowing or denying the user's access request |
RADIUS is a UDP-based authentication protocol that also uses a client/server model. RADIUS servers are usually used in conjunction with network devices, such as wireless access points (APs) and virtual private network (VPN) servers.
| step1 | The device receives an authentication request from the user |
| step2 | Device sends authentication request to RADIUS server |
| step3 | The RADIUS server authenticates the user, verifying the username and password |
| step4 | If the authentication is successful, the RADIUS server returns authorization information to the device, allowing or denying the user's access request |
Whether it is TACACS+ or RADIUS, their implementation requires the following components:
- Client (network device): initiates an authentication request, sending user credentials to the authentication server.
- Authentication Server: Receives and processes authentication requests, and verifies user credentials according to appropriate policies.
- User database: stores user information and credentials for the authentication process with the authentication server.
- Authentication Protocol: Determines the format and exchange rules for messages during the authentication process.
However, as network authentication protocols, TACACS+ and RADIUS do not support the encryption function, that is to say, the identity authentication data is transmitted in plain text, and there are certain security risks. It can be combined with security protocols such as SSL/TLS if encrypted communication is required.