Cyber Showdown CTF on One Nix Flake: The Little Things Nobody Warns You About

I recently played Cyber Showdown CTF on a pure Nix setup, and it convinced me that Nix is one of the best things to happen to my CTF workflow. It also broke a few binaries in ways that taught me more about how Linux actually loads a program than any blog post ever did. So this is two things at once. It is a practical guide to running a CTF lab on Nix: how to set it up, the everyday commands, and the advanced moves most people never find. And it is an honest field report of the friction, with real terminal output as proof, because a guide that only shows the happy path is lying to you. If you have never touched Nix, do not worry. I will explain the mental model before the machinery, and every command has a reason attached. Before any of the technical detail: my team, TU-2026-Team-08 (team motto, "win win win"), finished first, 17 of 24 flags for 12150 points. Every one of those flags came out of the Nix shell this post is about, so take the rest as proof the setup holds up under real…