Every Linux tutorial I've ever read tells you about a command. None of them hand you a real, broken box and say "fix it." So I built one that does: tmpfs.tech — hands-on Linux and open-source challenges that run on a live, throwaway VM you actually control, right in your browser.
How it works
- Pick a challenge → you get a real Linux session in an in-browser terminal (or SSH).
- The task is a genuine scenario, not a quiz: repair broken nginx, write an nftables ruleset, debug a failing systemd unit, fix a storage mount, eradicate cron-based persistence after a breach.
- The VM is ephemeral — spun up just for you, torn down when you finish. Nothing touches your own machine.
- Your work is graded automatically against the actual system state, so a pass means you really fixed it.
What's in it
Hundreds of challenges across sysadmin, networking, firewall, systemd, security, web/deploy, bash, storage, Kubernetes, plus offensive and IR tracks.
- Offensive Lab — local privilege-escalation CTF (SUID/sudo/passwd misconfigs).
- Defense & IR — evict rogue UID-0 accounts, kill systemd/cron persistence, attribute a breach from auth.log.
A few things I'm proud of
- Zero signup to start. Guest play works the moment you land.
- Truly isolated. Each session is its own VM, no internet egress, auto-reaped on idle.
- A skill ladder, not a syllabus. A rating recommends the next challenge by difficulty gap.
I'd genuinely love feedback on the challenge design — which tracks feel right, what's missing, and what you'd want to learn-by-breaking next.
Try it here: https://tmpfs.tech
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