For a long time, securing an API meant putting something in front of it. A reverse proxy, a gateway, an agent in the request path. Every one of those choices buys you visibility at a cost: added latency, and a new component that can fail and take your API down with it. Teams accepted that trade because there was no obvious alternative. Now there is.
The problem with sitting inline
An inline component touches every request before it reaches your application. If it is slow, your API is slow. If it crashes, your API is down. If it is compromised, the attacker is now in the most sensitive position in your stack. Security that sits inline is security that can become the incident.
There is a quieter problem too. Inline tooling usually inspects requests with pattern matching, because anything heavier would add unacceptable latency. That keeps it fast, but it also keeps it blind to anything that does not match a known pattern.
What eBPF makes possible
eBPF lets safe, sandboxed programs run inside the Linux kernel and observe what the system is doing, including network traffic, without modifying the application. For API security, that unlocks a different shape entirely.
- See everything from the kernel. Capture requests across HTTP, WebSocket and gRPC at the point they cross the kernel, with no library to import and no code change.
- Copy, do not intercept. Mirror a copy of the traffic to an analysis engine that runs out of band. The live request never waits on the analyzer.
- Analyze without a latency budget. Because analysis is off the hot path, you can run behavioral models and reasoning that would never fit inline.
The live path and the analysis path are separated. A problem in the analyzer can never slow or break production, because production was never routed through it.
Out of band does not mean after the fact
A common worry is that watching out of band means you can only react late. In practice the copy reaches the analyzer in real time. Detection lands in a couple of milliseconds, fast enough to drive a kernel-level block on the offending connection while the live path keeps serving everyone else untouched. You get the safety of being off the hot path and the speed of being right next to it.
Why this is becoming the default
The same kernel-level observability that transformed networking and monitoring is now doing it for security. It removes the latency tax, removes the single point of failure, and frees detection to be as smart as the threat requires. As more teams adopt service meshes and polyglot protocols, the inline gateway looks more and more like the bottleneck it always was.
This is the architecture behind cyron.io. The iris agent is a single Docker container that taps traffic with eBPF, mirrors it out of band, and analyzes behavior across HTTP, WebSocket and gRPC, adding zero latency to your live requests.