How a RADIUS server works

A RADIUS server utilizes a central database to authenticate remote users. RADIUS functions as a client-server protocol, authenticating each user with a unique encryption key when access is granted. How a RADIUS server works depends upon the exact nature of the RADIUS ecosystem. Below is an overview of how RADIUS servers work.

  1. First, the user initiates authentication to the network access server (NAS).

  2. The network access server then requests either a username and password or a challenge (CHAP).

  3. The user replies.

  4. Upon receiving the user’s reply, the RADIUS client sends the username and the uniquely encrypted password to the RADIUS server.

  5. The RADIUS server accepts or rejects the user.

RADIUS servers are well known for their AAA capabilities — Authentication, Authorization, and Accounting. The main advantage of the centralized AAA capabilities of a RADIUS server are heightened security and better efficiency. RADIUS servers provide each business with the ability to preserve the privacy and security of both the system and each individual user.