Getting Started with eBPF: A Practical Introduction

If you’ve been following cloud native technologies, you’ve probably heard the buzz around eBPF. It’s been called everything from “the future of Linux” to “superpowers for system observability.” But what actually is it, and why should you care?

What is eBPF?

eBPF stands for “extended Berkeley Packet Filter.” The name is a bit misleading—while it evolved from packet filtering technology, modern eBPF is much more powerful. At its core, eBPF lets you run sandboxed programs inside the Linux kernel without modifying kernel source code or loading kernel modules.

Think about that for a moment. You can write custom code that runs at the kernel level, with direct access to system events, but in a safe, verified way. That’s a big deal.

Why It Matters

Traditional approaches to kernel-level observability required either:

1. Modifying kernel source code — Complex, slow, requires rebuilding the kernel
2. Loading kernel modules — Risky, can crash the system, difficult to maintain
3. Using existing kernel interfaces — Limited to what’s already exposed

eBPF changes the game by providing a safe, dynamic way to extend kernel functionality. Programs are verified before loading to ensure they can’t crash the kernel or cause security issues.

Real-World Applications

Observability

Tools like Cilium and Pixie use eBPF to provide deep observability into Kubernetes clusters. You can trace network packets, monitor system calls, profile CPU usage—all without instrumenting your application code.

Networking

eBPF enables high-performance packet processing. Cloudflare uses it to handle DDoS protection at scale. Facebook uses it for load balancing.

Security

Runtime security tools use eBPF to detect suspicious behavior at the system call level. You can create policies that alert on or block specific actions.

A Simple Example

Here’s a minimal eBPF program that traces execve system calls (when new programs are executed):

#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>

SEC("tracepoint/syscalls/sys_enter_execve")
int trace_execve(struct trace_event_raw_sys_enter *ctx)
{
    char comm[16];
    bpf_get_current_comm(&comm, sizeof(comm));
    bpf_printk("execve called by: %s", comm);
    return 0;
}

char LICENSE[] SEC("license") = "GPL";

This program attaches to the execve tracepoint and logs which process made the call. Simple, but it demonstrates the power—you’re running code inside the kernel!

Getting Started

If you want to explore eBPF, here are some resources:

1. libbpf-bootstrap — Minimal examples to get you started
2. BCC — Python and Lua bindings for eBPF
3. bpftrace — High-level tracing language
4. Learning eBPF by Liz Rice — Excellent book on the topic

What I’m Exploring

I’ve been building small eBPF tools to understand how systems behave under load. There’s something deeply satisfying about being able to answer questions like:

• Which processes are causing the most disk I/O?
• What’s the latency distribution of specific system calls?
• Who’s opening this file?

These questions used to require expensive commercial tools or tedious log analysis. With eBPF, you can write a targeted program and get answers in real-time.

Conclusion

eBPF represents a fundamental shift in how we can interact with the Linux kernel. For anyone interested in observability, performance, networking, or security, it’s worth investing time to understand.

I’ll be writing more about specific eBPF projects and use cases in future posts. If you have questions or want to discuss, find me on GitHub or Bluesky.