RADIUS The system is commonly used for the purpose of centralizing authentication, authorization and accounting of network access. VPN, on Wi-Fi business and 802.1X ; the server usually receives requests fromAuthentication on UDP 1812 and must recognize the network client and its shared secret.
Simple definition
RADIUS centralizes authentication, authorisation and accounting of many network accesses.
Technical definition
RemoteAugination Dial-In User Service exchange AAA queries between network equipment and identity server.
Separate network, policy and identity in RADIUS
Test in this order: arrival of the request on the server, client recognition RADIUS and secret, policy selection, then validation of the user or certificate. This method avoids changing the directory when the server receives nothing, or the firewall while NPS explicitly rejects the policy. Keep an identical test after each change to compare the result.
What is it used for?
authenticate VPN, Wi-Fi company, 802.1X and certain administrative equipment.
Practical example
one firewall validate accounts VPN with an NPS/ serverRADIUS.
How to diagnose authentication RADIUS ?
Start by checking that the server RADIUS receives a request from theIP address of the network client declared.Then, check the Shared secret, the port used — often UDP 1812 for authentication — then the rules or policies that determine whether the request is accepted. Server logs, for example NPS on Windows Server, often indicate whether the failure is networked, policy or identity.
Common issues
An incorrect shared secret may look like a lack of response, while an NPS policy or a non-compliant group produces a rejection after receiving the request. 802.1X, certificates and EAP type add an extra layer. A translation NAT or a bad source address may also make the request appear as coming from a client RADIUS Undeclared.
FAQ — RADIUS
Which ports RADIUS Are the most common?
UDP 1812 is commonly used for authentication and UDP 1813 for accounting; some historical environments use other ports.
What is a customer RADIUS ?
It’s the equipment that sends the request to the server RADIUS, e.g. a firewall, a controller Wi-Fi or switch.
RADIUS Does it encrypt all user traffic?
No. RADIUS transports AAA exchanges; encryption of user traffic depends on the VPN, Wi-Fi, of 802.1X or the relevant access protocol.