accesslimiting

Access limiting refers to techniques that regulate how, when, and by whom a resource can be accessed. It encompasses mechanisms that cap throughput, restrict access to certain users or endpoints, and enforce time-based or quota-based constraints. It is distinct from authentication and authorization, focusing on limiting usage patterns and risk exposure rather than identifying users.

Common approaches include rate limiting, quotas, and access control lists. Rate limiting restricts the number of operations over a sliding window or token bucket; quotas set a maximum amount over a period. Access control models such as ACLs, RBAC, and ABAC define which principals may request resources and under what conditions.

Implementation often occurs at multiple layers. Network elements like firewalls, reverse proxies, and API gateways can enforce limits at the edge; application logic can enforce per-user or per-session controls. Techniques include IP-based throttling, user-based limits, concurrency caps, and token-based authentication with time-bound credentials. CAPTCHAs or challenges may be used to deter automated abuse.

Common use cases include protecting APIs from abuse, preventing login brute force, managing billing and service quotas in cloud platforms, and reducing load on backend systems during traffic spikes.

Key considerations include balancing security with usability, handling legitimate bursts, monitoring and logging for anomaly detection, privacy implications of traffic analysis, and ensuring scalable, low-latency enforcement. Misconfigurations can cause denial of legitimate access or permit abuse.