Linux for air-gapped Bitcoin cold storage. A kernel that cannot network. Free, open source, byte-reproducible. Offline by design. Sovereign by default
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Joined August 2026
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## Thread (15 posts)
**1/** We built a Linux distro whose kernel *cannot* network. Not "firewall rules". Not "just don't plug it in". The networking code isn't compiled in — at all. It's called COLDIRON OS, it's free, and here's the proof. 🧵
You can test COLDIRON without hardware: QEMU boots the ISO in 10 minutes and coldiron-check runs on boot. No USB stick, no laptop to sacrifice. Found a bug? It goes on the wall of fame, not into a bounty spreadsheet. Community-built, publicly credited.
What does "the kernel cannot network" actually mean? No network drivers compiled in. No module subsystem to load them later. IPv4 and IPv6, both gone. Not a firewall rule you can flip back: there is no stack left to enable. The property is structural, not configured.
Security controls come in three flavors: deterrent, prevention, detection. A policy ("we keep it offline") is a deterrent — it stops honest people and nobody else. Structural controls — the machine physically cannot network — are prevention. Design for prevention, not promises.
Stuxnet (2010) took out air-gapped centrifuges — via a USB stick. Not the internet, not a firewall: a USB stick. That's why cold storage needs a machine where "plugging things in" can't become a pivot. No drivers, no modules, nothing to load.
Three ways an "offline" machine actually gets owned: 1) a network it shouldn't have — Wi-Fi, phone tethering, a cable; 2) storage that walks in — USB, SD, a charger that isn't one; 3) the human, social-engineered. An air gap only exists when all three are structurally impossible.
Every self-custody setup has one weak point: the machine that signs. It's *supposed* to stay offline. "Supposed to" is not a security control — it's a hope. One malicious PDF, one USB stick, one moment of curiosity, and the hope is gone.
**14/** v0.3.0 is the launch release. v0.4.0 is next: Secure Boot + a fresh signing key — the "trust-anchor release". The roadmaps are public, the builds are public, the failures will be public too.
**15/** Try it. Star it. Fork it. Break it. Report it. That's the whole pitch — we'll keep shipping receipts either way.
github.com/rurogge/coldiron-…
rurogge.github.io/coldiron-o…
