RADIUS Explained: How It Works and What to Look For
RADIUS centralizes authentication, authorization and configuration for network access.
Published by Protocol Explorer · Reviewed
How RADIUS works
A network access server sends an Access-Request to a RADIUS server, which can respond with Access-Accept, Access-Reject or Access-Challenge.
What to look for in an exchange
Read the packet code, identifier and attributes. RADIUS is a client-server protocol between the access device and authentication service, not a browser login page.
Follow an example step by step
- Match the Access-Request identifier to the response from the RADIUS server.
- Inspect attributes that describe the user, access device and requested service where visible.
- Distinguish Access-Challenge from final Access-Accept or Access-Reject.
Common interpretation mistake
The network access device and the authentication server have different roles; the end user is not necessarily the RADIUS client.
Key point to remember
RADIUS deployment security depends on the transport and configuration as well as the protocol messages.
Explore the protocol
The RADIUS overview is free without an account. Its full interactive lesson is included in Protocol Explorer Pro, a one-time $4.99 purchase; an account is required to buy Pro and restore the licence across devices.
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Specification
Read the primary specification for RADIUS for the authoritative protocol details. The interactive scenario is a simplified teaching model, not a capture of your network.
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