RADIUS vs TACACS: What To Choose For Your Enterprise?

RADIUS vs TACACS: What To Choose For Your Enterprise?
RADIUS vs TACACS: What To Choose For Your Enterprise?

As cyber threats grow more advanced, securing enterprise networks has become mission-critical. A robust authentication framework ensures only authorised users can access sensitive systems and data. This is where AAA (Authentication, Authorisation, and Accounting) protocols like RADIUS and TACACS+ prove pivotal.

But between the two, which one should your business implement? In this blog, we will analyse the key differences between RADIUS vs TACACS+ in terms of architecture, security, flexibility and use cases to help inform strategic decisions suitable for your infrastructure and organisation requirements in the ever-evolving cyber risk landscape.

Authentication in Enterprise Networks

To understand why RADIUS and TACACS+ matter, let's first examine why rigorous authentication is vital in enterprise environments.

As companies digitise operations and adopt cloud computing, their networks grow increasingly complex. More users, devices, applications, and data mean more potential entry points for cyberattacks.

From advanced malware to insider threats, businesses need resilient safeguards. Compromised credentials represent a major vulnerability. According to 2022 Verizon's Data Breach Investigations Report, over 80% of hacking-related breaches involved stolen or brute-forced credentials.

This is where the "Authentication" component of AAA protocols comes into play. By verifying each user's identity, RADIUS and TACACS+ establish the first line of defence.

What is RADIUS?

A popular networking protocol, RADIUS (Remote Authentication Dial-In User Service), centralises device authentication, authorisation, and accounting (AAA) administration.

RADIUS authenticates and controls clients connecting to servers or network resources via dial-up, wireless, and VLAN. Users' profiles and verification information are stored on RADIUS servers to verify identities and set network device access rights.

How RADIUS Works

Operating on a client-server model, RADIUS requires the user device to act as a client that initiates authentication requests to the RADIUS server. The centralised server then checks the user credentials against its database and returns an access-accept or access-reject response.

RADIUS can facilitate various authentication methods like passwords, tokens, and biometrics.

Advantages and Disadvantages of RADIUS


  • Interoperable with multiple devices and vendors, allowing centralised authentication across heterogeneous networks
  • Fast performance and reduced latency by using connectionless UDP transport
  • Simple to scale across large enterprise networks with multiple RADIUS servers
  • Cost-effective to implement compared to proprietary solutions
  • Flexible support for various authentication methods beyond just passwords


  • Only encrypts the password field in RADIUS packets, leaving other information unencrypted
  • Lacks the reliability features of TCP protocols, with no built-in retransmission of lost packets
  • No separation of authentication and authorisation functions; less flexible access control
  • Potential single point of failure if only one RADIUS server is deployed
  • Sensitive to latency and interoperability issues if improperly configured

What is TACACS+?

The authentication, authorisation, and accounting (AAA) protocol TACACS+ centralises network device and user access control with strong security. Separating AAA services into modules allows granular control over each aspect. Multipacket encryption with AES or MD5 hashing secures all client-server connections in TACACS+. Detailed accounting/audit records, dependable TCP transports, and customisable authentication mechanisms are key.

How TACACS+ Works

TACACS+ utilises a client-server model where network devices act as clients requesting access that is then authorised or denied by the TACACS+ server. It separates authentication, authorisation, and accounting into distinct processes for more modular security services. Entire packet contents are encrypted using MD5 hashing between clients and servers.

Advantages and Disadvantages of TACACS+


  • Robust AES or MD5 encryption for secure transport of all communications
  • Granular access control and custom user permissions for authorisation
  • Detailed logging and reporting for auditing user activity
  • Flexible to customise authentication, authorisation, and accounting services
  • Multifactor and multifunction authentication capabilities beyond passwords
  • Separation of authentication, authorisation, and accounting functions
  • Reliability from the use of TCP protocols and sequencing of packets


  • Complex configuration management with three distinct services to maintain
  • Increased processing overhead due to reliable TCP transports
  • Tight coupling architecture demands properly functioning servers
  • Less standardised than other AAA protocols like RADIUS
  • Typically more resource-intensive and expensive solution to implement
  • Encryption limits visibility into user communications for troubleshooting

TACACS+ vs RADIUS - Key Differences

Authentication and Authorisation Methods

A core difference lies in authentication and authorisation handling - RADIUS combines them into one process during user login, while TACACS+ separates these into distinct modular services for added flexibility. TACACS+ allows customising each independently.

Encryption and Security Levels

RADIUS offers basic data security via encrypting only the password in access request packets sent from client to server. TACACS+ enables robust security by encrypting the entire packet contents for all communications between client and server using AES or MD5 hashing algorithms.

Transport Protocols and Reliability Tradeoffs

RADIUS leverages connectionless UDP for faster packet transfer yet lacks reliability assurances provided by TCP handshaking, which TACACS+ uses. This leads to a classic speed vs reliability tradeoff between the two protocols.

Architectural Complexity and Integration

RADIUS uses a simple client-server access model, while TACACS+ entails a more complex modular architecture separating AAA services, necessitating tighter integration and coupling with servers during implementation.

Authorisation Granularity and Control

A major advantage of TACACS+ includes finer-grained authorisation controls allowing command/feature level access and enhanced custom permissions, which RADIUS does not provide natively, resulting in all-or-nothing access.

Interoperability Considerations

RADIUS offers broad cross-platform and multi-vendor operability. TACACS+ provides deep Cisco environment integration but can lack versatility across heterogeneous infrastructure, impacting legacy support.

RADIUS suits the needs of small and medium businesses, while large banks and enterprises with advanced security use cases tend to utilise the strong protections of TACACS+ more substantially due to regulatory compliance and risk management needs.

Which One Is Right for Your Business?

  • Simplicity and Interoperability: If ease of implementation across diverse devices is critical, RADIUS is likely the better fit with broad cross-platform support and a more straightforward centralised architecture.
  • Budget Concerns: RADIUS servers are typically cheaper to purchase and manage compared to the more advanced TACACS+ setup.
  • Granular Access Control: TACACS+ enables fine-grained authorisation tuning to user roles and groups. Its command authorisation facilitates tighter access policies.
  • Regulatory Compliance: Healthcare, finance, or other highly regulated industries benefit from TACACS+ detailed logging, strong encryption, and customisable access controls to address compliance needs.
  • Cisco-Centric Environments: Organisations using predominantly Cisco networking equipment integrate better with native TACACS+ implementations for routing infrastructure and device management security.
  • Elevated Security Posture: For organisations facing high cyber threats, TACACS+ multifactor authentication, reliable TCP transport, modular architecture and encryption capabilities provide robust AAA services.


When it comes to the TACACS+ vs RADIUS debate, both provide robust authentication mechanisms. However, selection depends on individual and organisational priorities around risk, compliance, support needs, and infrastructure.

As networks continue expanding, it becomes even more critical to implement cybersecurity solutions tailored to enterprise environments through ongoing assessments.

We offer strategic AAA security with leading Multi-Factor Authentication capabilities, enhancing network visibility and control while meeting complex policy and technology demands.

With Instasafe's solutions safeguarding access, companies can drive innovation with confidence.

Frequently Asked Questions (FAQs)

1. When would you recommend using TACACS+ over RADIUS?

TACACS would be recommended over RADIUS when more granular control and multifactor authentication are needed, as TACACS separates authentication, authorisation, and accounting while RADIUS combines them.

2. What is RADIUS? What advantage does it have over TACACS+?

RADIUS is a common network protocol used for remote user authentication and access control. A key advantage over TACACS is wider vendor support across network devices.

3. Which two features are included by both the TACACS+ and RADIUS protocols chosen?

Features included by both TACACS+ and RADIUS protocols are a client/server model for user authentication, support for multiple authentication methods like one-time passwords, and the ability to centrally manage access policies.