AAA stands for Authentication, Authorization, and Auditing. It is the access-control layer that confirms a user’s identity, decides what that user is allowed to do, and records activity for later review. In practice, AAA is often implemented by gateways, VPN concentrators, identity servers, and other front-door systems that sit between users and internal resources.
AAA matters because it protects the trust boundary. If authentication is bypassed, an attacker may gain entry without valid credentials. If authorization is weak, a legitimate user may reach systems beyond their role. If auditing is missing or incomplete, defenders lose visibility into misuse, lateral movement, and policy violations. In attacks, AAA weaknesses often appear as login bypasses, session abuse, or policy misbinding. In defense, strong AAA design depends on strict policy checks, least-privilege access, centralized logging, and regular review of authentication paths.