RADIUS (Remote Authentication Dial In User Service)

Remote Authentication Dial-In User Service (RFCs 2865/2866) is the long-standing AAA protocol used for network access authentication, accounting, and authorisation, Wi-Fi 802.1X, VPN, and many enterprise systems. RADIUS uses a shared secret and is being progressively replaced by Diameter in carrier-class deployments and by RadSec (RADIUS over TLS) for transport security.

Categories: Radio Access NetworkSignalingSecurity Controls

RADIUS in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

Signaling protocols carry the control-plane instructions that set up calls, register subscribers, hand over sessions and route SMS. SS7, Diameter, GTP-C and SIP are the four dominant families, and interconnect exposure of any of them is treated by GSMA FS.11 / FS.19 / FS.20 as a top-tier telecom risk.

To place RADIUS in the wider telecom-security picture, review RTP, Diameter, IPsec, PSTN, Service-Based Architecture (SBA) Security and SIP.

Related terms

Equipment

Authentication servers (AUSF, 3GPP AAA, HSM)

Articles in the P1 mobile network security guide

Related topic hubs

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.