O-RAN Interfaces (A1, E2, O1, O2)

In telecommunications, the O-RAN Alliance defines several open interfaces: A1 between Non-RT RIC and Near-RT RIC for policy and ML model lifecycle, E2 between Near-RT RIC and RAN nodes for near-real-time control, O1 between SMO and managed elements for FCAPS, and O2 between SMO and the cloud platform hosting RAN functions. Each interface introduces its own attack surface that must be hardened.

Categories: Radio Access NetworkSignalingThreats and Attacks

O-RAN Interfaces (A1, E2, O1, O2) in context

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

Signaling protocols carry the control-plane messages that set up calls, register subscribers 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 as top-tier telecom risk.

To place O-RAN Interfaces (A1, E2, O1, O2) in the wider telecom-security picture, review Lawful Interception Abuse Risk, Lawful Interception Architecture, Revenue Assurance, Telecom Penetration Testing, Chain of Custody and Bidding-Down Attack — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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