All about RADIUS Server

 

 What Is a RADIUS Server?

RADIUS (Remote Authentication Dial-In User Service) is a network protocol and server that provides centralized Authentication, Authorization, and Accounting (AAA) for users connecting to a network. It is widely used to authenticate users for:

• VPN access
• Wi-Fi networks
• Network devices (routers/switches)
• Enterprise login systems

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 How RADIUS Works

1. User connects to a device (e.g., Wi-Fi AP, VPN).
2. The NAS (Network Access Server) forwards credentials to the RADIUS server.
3. RADIUS:
   • Authenticates user (usually via a database like LDAP, AD, or local file).
   • Authorizes access level (e.g., VLAN, firewall rules).
   • Logs usage/accounting data (e.g., session time, data used).
4. User is granted or denied access.

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 Key RADIUS Server Software

• FreeRADIUS (most popular open-source RADIUS server)
• Microsoft NPS (Network Policy Server)
• Cisco ISE
• Radiator
• TekRADIUS
• daloRADIUS (web frontend for FreeRADIUS)

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 Real-World Applications of RADIUS Server (50 Use Cases)

 Authentication for Network Access

1. Enterprise Wi-Fi authentication (802.1X)
2. VPN user login authentication
3. Wired network 802.1X port authentication
4. Multi-factor authentication (MFA) integration
5. SSH access control for Linux servers
6. Admin login to Cisco switches and routers
7. Authentication for wireless controllers
8. Guest Wi-Fi login portals
9. IoT device onboarding (with MAC address auth)
10. Access control for VoIP phones

 Enterprise & Identity Management

11. Single Sign-On (SSO) integration
12. LDAP or Active Directory integration
13. Dynamic VLAN assignment based on user role
14. Device fingerprinting and policy enforcement
15. BYOD (Bring Your Own Device) policy enforcement
16. MAC address authentication (for devices without login screens)
17. Eduroam (education roaming networks in universities)
18. Corporate laptop authentication on Wi-Fi
19. Role-based access control to network resources
20. Integration with Identity Providers (IdPs)

 ISP & Telecommunications

21. DSL, PPPoE, and fiber subscriber authentication
22. Bandwidth usage accounting and quota tracking
23. Time-based prepaid internet access
24. Wireless ISP customer authentication
25. Internet cafes and hotspot control
26. Metro Wi-Fi billing and authentication
27. User data logging for telecom compliance
28. Hotel guest internet login system
29. Multi-tenant broadband access systems
30. Prepaid or voucher-based network access

 Network Infrastructure Management

31. AAA for network admin access to firewalls
32. Logging admin commands via accounting
33. Session timeout and idle logoff policies
34. Admin authorization by role (e.g., read-only or config)
35. Failover authentication when LDAP/AD is down
36. Network usage analytics per user/device
37. Custom policies based on login time or location
38. Alerts for suspicious login behavior
39. Access restriction based on IP or location
40. Merging different directory sources (e.g., AD + SQL)

 Education & Public Networks

41. School or campus Wi-Fi login
42. University dorm network access control
43. Library internet usage tracking
44. Community center internet control
45. Municipal Wi-Fi access logging
46. Event Wi-Fi with user registration portals
47. High school laptop/Wi-Fi filtering
48. Student-to-staff network segregation
49. Time-limited access for exam environments
50. Staff BYOD policy enforcement with RADIUS

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 Summary

Feature	Benefit
Centralized AAA	Manage all network access from one point
Secure 802.1X	Prevent unauthorized Wi-Fi/wired use
Role-based access	Assign VLANs, permissions per user group
Logs + Compliance	Track usage, meet regulatory standards
Extensible	Supports AD, LDAP, SQL, OTP, MAC auth, etc.