API security: OAuth 2.0, gateway, rate limiting, DDoS

OAuth 2.0 for Network APIs

Securing network APIs is critical because they expose sensitive capabilities — location tracking, QoS modification, and subscriber data queries. 5G network exposure uses OAuth 2.0 as the primary authorization framework. The AF first registers with the NRF or an external authorization server and obtains client credentials. Before each API call, the AF requests an access token by presenting its credentials and specifying the desired scope — for example, event-exposure or traffic-influence. The NEF validates the token on every request, checking expiration, scope, and audience claims before…