---
title: "eBPF on Hard Mode"
url: https://daily.dev/posts/ebpf-on-hard-mode-xc9nqtwhy
source_url: https://feyor.sh/blog/ebpf-on-hard-mode/
type: article
source: "Lobsters"
published: 2026-02-21T13:58:18.282Z
updated: 2026-02-21T13:58:42.566Z
tags: ["linux", "zig"]
reading_time: 20
upvotes: 0
comments: 0
language: en
---

> ## Documentation Index
> Fetch the complete documentation index at: https://daily.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# eBPF on Hard Mode

**[Lobsters](https://daily.dev/sources/lobsters)** · 20 min read · 0 upvotes · 0 comments

## Summary

A deep dive into writing eBPF programs at the raw bytecode level without libbpf, LLVM, or GCC, using Zig as the host language. Covers the full workflow: loading programs via the bpf() syscall, using eBPF maps for kernel-userspace data sharing, writing socket filter and sk_skb programs, and constructing BTF (BPF Type Format) objects manually to satisfy the verifier for features like subprograms, callbacks (bpf_loop), and KFuncs (bpf_strcmp). Includes working code examples for a packet filter that drops packets containing 'foobar', privilege requirements (CAP_BPF, CAP_NET_ADMIN, CAP_PERFMON), and parsing btf_vmlinux to look up KFunc BTF IDs at runtime. A Nix flake for running the examples in QEMU is also provided.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://feyor.sh/blog/ebpf-on-hard-mode/>

## Similar posts on daily.dev

- [eBPF the Hard Way](https://daily.dev/posts/ebpf-the-hard-way-ru1cateai) · Lobsters · 1 upvotes · 0 comments

---

Tags: [#linux](https://daily.dev/tags/linux), [#zig](https://daily.dev/tags/zig)

[View this post on daily.dev](https://daily.dev/posts/ebpf-on-hard-mode-xc9nqtwhy)