Authentication protocols play a critical role in securing network access, and two of the most widely used protocols are TACACS (Terminal Access Controller Access-Control System) and RADIUS (Remote Authentication Dial-In User Service) tacacs vs radius . In this blog, we’ll delve into the intricacies of TACACS and RADIUS, exploring their differences in terms of authentication, authorization, encryption, use cases, and more.

TACACS vs RADIUS
Table of Contents
Authentication and Authorization ( tacacs vs radius )
TACACS: TACACS stands out for its separation of authentication and authorization processes. This modularity allows for more granular control over user access permissions. TACACS+ (an updated version of TACACS) introduces additional features, including command-level authorization, offering administrators fine-tuned control over users’ actions on network devices.
RADIUS: In contrast, RADIUS combines the authentication and authorization processes into a single step. While it provides a simpler approach, it may lack the granularity offered by TACACS. RADIUS is often used in scenarios where a broader stroke of access control is sufficient.
Encryption
TACACS: TACACS provides robust encryption for the entire authentication and authorization process. This emphasis on security makes it a preferred choice in environments where protecting sensitive data during transmission is paramount.
RADIUS: While RADIUS does incorporate encryption, it generally uses weaker encryption compared to TACACS. The security level is still robust, but organizations with higher security requirements might lean towards TACACS.
Port Numbers and Packet Structure
- TACACS: TACACS communication occurs over TCP using port 49. It adopts a packet-oriented structure, enabling a more detailed and nuanced exchange of information between the client and the server.
- RADIUS: RADIUS communication is typically carried out over UDP, with ports 1812 for authentication and 1813 for accounting. Its packet structure is simpler, emphasizing efficiency in communication.
Use Cases
- TACACS: TACACS has traditionally found its niche in network device management scenarios. Its ability to provide detailed command-level access control makes it particularly suitable for securing access to routers, switches, and other networking devices.
- RADIUS: RADIUS is versatile and commonly used in various scenarios, such as remote user access, network access control, and Virtual Private Networks (VPNs). Its broad applicability makes it a preferred choice in diverse networking environments.
Vendor-Specific Attributes (VSAs) and Security
TACACS and RADIUS: Both protocols support Vendor-Specific Attributes (VSAs), allowing for the incorporation of proprietary extensions. This feature enhances flexibility in implementation and supports vendor-specific functionalities.
In terms of security, TACACS is often considered more secure due to its distinct processes for authentication and authorization. RADIUS, while secure, may be perceived as less secure because of its combined nature.
Tacacs vs Radius ?
Feature | TACACS | RADIUS |
---|---|---|
Authentication | Provides separate processes for authentication, authorization, and accounting. | Combines authentication and authorization into a single process. Accounting is a separate process. |
Encryption | Supports encryption for the entire authentication and authorization process. | Typically uses weaker encryption compared to TACACS. |
Port Numbers | Uses TCP port 49 for communication. | Uses UDP ports 1812 (authentication) and 1813 (accounting). |
Packet Structure | Uses a packet-oriented structure for communication, allowing for more granular control. | Uses a simpler packet structure, with a focus on simplicity and efficiency. |
User Access Control | Offers more granular control over user access permissions through command-level authorization. | Generally provides a broader stroke of access control compared to TACACS. |
Application Support | Historically used more in network device management scenarios (routers, switches). | Commonly used for network access scenarios, including dial-up and VPNs. |
Vendor Specific Attributes | Supports Vendor-Specific Attributes (VSAs) for extended functionality. | Also supports VSAs for proprietary extensions. |
Security | Generally considered more secure due to the separation of authentication and authorization. | Offers good security but may be considered less secure due to the combined nature of authentication and authorization. |
Use Cases | Well-suited for scenarios where detailed control over command-level access is required, such as network device management. | Often used in scenarios like remote user access, network access control, and VPNs. |