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RADIUS & TACACS+ Authentication

Centralized AAA (Authentication, Authorization, Accounting) protocols for network device access control

AAA (Authentication, Authorization, Accounting)

AAA provides centralized access control for network devices, ensuring only authorized users can access network resources with appropriate privileges while maintaining detailed audit logs.

Authentication

"Who are you?"

  • Verify user identity
  • Username/password validation
  • Multi-factor authentication
  • Certificate-based auth
Authorization

"What can you do?"

  • Determine user privileges
  • Command-level access
  • Time-based restrictions
  • Resource-specific permissions
Accounting

"What did you do?"

  • Log user activities
  • Command tracking
  • Session monitoring
  • Compliance reporting
Why Use Centralized AAA?
  • Scalability: Manage hundreds of devices centrally
  • Consistency: Uniform access policies
  • Security: Centralized credential management
  • Compliance: Detailed audit trails
  • Efficiency: Single point of user management
  • Flexibility: Dynamic privilege assignment
  • Monitoring: Real-time access tracking
  • Recovery: Centralized backup and restore

Server Components Architecture

Authentication Database

Stores user credentials and authentication policies

Local usersLDAP/Active DirectorySQL DatabaseExternal authentication
Authorization Policies

Defines what resources users can access

Role-based accessAttribute-based policiesTime-based restrictionsDevice-specific rules
Accounting System

Logs and monitors user activities

Command loggingSession trackingResource usageCompliance reporting
Network Access Server (NAS)

Client device that forwards authentication requests

RoutersSwitchesWireless controllersVPN gateways

🔑 Protocol Quick Facts

RADIUS:
  • RFC 2865 (Authentication)
  • RFC 2866 (Accounting)
  • UDP-based protocol
  • Industry standard
TACACS+:
  • Cisco proprietary
  • TCP-based protocol
  • Full packet encryption
  • Granular authorization

Common Use Cases

Network Device Access

Router, switch, and firewall management

Wireless Authentication

Enterprise Wi-Fi access control

VPN Access

Remote access authentication

Physical Access

Door controllers and security systems