Infrastructure & Operations › Linux & Servers

eBPF

Running safe, sandboxed programs inside the Linux kernel for tracing and networking.

Also known as: eBPF, extended Berkeley Packet Filter, bpf

eBPF lets you run small, sandboxed programs inside the Linux kernel without changing the kernel or loading a custom module. A program attaches to a hook — a system call, a network packet, a function entry — and runs when that event happens, with access to kernel data. A verifier checks each program before it loads to ensure it terminates and can’t crash or corrupt the kernel, which is what makes running code in the kernel safe.

event (syscall, packet, kprobe) → eBPF program → observe / filter / aggregate

Its uses fall into three areas:

• Observability — trace system calls, collect per-process metrics, profile CPU usage, see network connections, all with low overhead and without modifying the application.
• Networking — implement load balancing, packet filtering and routing in the kernel, fast and programmable.
• Security — enforce or monitor behaviour at the kernel boundary (see attack surface).

The appeal is visibility without recompiling anything. Conventional tools can see a process from the outside; eBPF can see inside the kernel’s view — which file descriptors, which connections, which latency — for the whole system at once, not one process at a time.

The classic mistakes:

• Assuming it’s universal. eBPF needs a reasonably modern kernel and the right privileges to load programs. Older kernels or locked-down environments may not support it, and distributions differ.
• Treating it as risk-free. The verifier makes it safe from crashing the kernel, not risk-free: a badly designed program can still add overhead or mis-observe. Test before production.
• Expecting it to replace application instrumentation. eBPF sees kernel-level events; it can’t know your business logic. It complements application-level tracing, not replaces it.
• Ignoring the privilege. Loading eBPF generally requires elevated rights. Who can run programs affects your attack surface, so treat the capability as privileged.
• Naming specific tooling versions. The ecosystem moves quickly; the concept is stable, the tools change.

When it matters: when you need deep, low-overhead, system-wide insight — performance analysis, security monitoring, or high-performance networking — that normal tooling can’t provide. It’s a powerful, advanced part of the Linux observability and networking toolbox, and increasingly the engine behind modern tooling.