claude-hdb
aba7015e53
The drill covered the CLI surface and basic egress but never probed the one claim everything hinges on: it only ever had one box running, so sibling isolation — #12's central, never-reproduced finding — went untested. Phase C now clones a peer and probes box-to-box reachability (with a listener, so "refused" cannot masquerade as "dropped"), DNS enumeration, IPv6-off, and host-to-box inbound. A new phase D applies the exact changes #16 proposes (dns.mode=none, NIC filtering, @internal) and watches what breaks — a FAIL there is a design veto caught before the code is written. The run ends with an answers block to paste into issue #15. Also: defaults now install heavy-duty/claudebox@main (the old default pointed at a fork branch that stopped moving when #13 merged), the version check compares against the installed VERSION file instead of a hardcoded 0.3.0, and the blind sleep after start became an agent poll. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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The drill
An end-to-end rehearsal of claudebox against a real Incus: install the CLI, set up the host, mint boxes, drive the whole surface, check that the isolation actually holds — and run the full #15 audit, including a live rehearsal of the hardening #16 proposes. It ends with a block of audit answers to paste into #15.
⚠ It rearranges the host it runs on. Incus, a systemd unit, a network, an ACL, a profile, rewritten firewall rules — and, in the last phase, deliberate mutations to the network and profile. Run it on a machine you can format — a spare server, a cloud VM you'll destroy, a VM on your laptop. Not your workstation.
git clone https://github.com/heavy-duty/claudebox && cd claudebox
bash drill/drill.sh --yes # run and forget; omit --yes to be asked first
Useful flags: --ref <branch> (drill a branch rather than main),
--keep-boxes (leave the boxes up to poke at — note the last phase's network
and profile mutations stay applied with them).
Exit 0 means every check passed. Roughly 20 minutes, most of it the cold box.
Why it exists
The repo has no tests and no CI, and the CLI is a shell script that shells out to
incus. That means the interesting failures are not in the bash — they are in
what Incus actually does, which is exactly what unit tests would stub out and get
wrong. The drill runs the real thing.
What it checks
A. Incus semantics. The assumptions claudebox is built on, probed directly:
that incus config get <inst> user.claudebox returns 1 (this is on the path of
every box command — if it lies, everything fails closed); that the
user.claudebox=1 list filter selects our instances and excludes an untagged
one; that --columns nstS gives four clean CSV fields; that the state column
reads RUNNING; that incus rename really does refuse a running instance; that
snapshot-list's first CSV field is the label; that an unset config key reads
as empty with exit 0 (#15 B4); and that incus copy preserves user.* keys
(#15 B2 — the whole template-metadata design in #17 rests on it).
B. The surface. Mint, list, info, snapshot, clone-from-a-snapshot-of-a-
renamed-box, rename (running must refuse, stopped must work), the escape hatch
and its isolation warning, the rm confirmation guard, and the CLI contract
(typo'd command, typo'd flag, list <box>).
The boundary gets its own treatment: the drill launches an instance
claudebox did not mint, aims down, rm and the escape hatch at it, and
requires all three to refuse — and the instance to still be standing afterwards.
C. Isolation baseline (#15 section A). From inside a real box: public egress works; the box cannot reach a listener on the host's claudenet gateway; RFC1918 is dropped; a sibling box is unreachable (a listener runs on the peer so "refused" — the packet arrived — cannot masquerade as "dropped"); whether DNS enumerates the sibling is recorded (#12 predicts it leaks today; that is audit data, not a failure); IPv6 is off; and the host cannot connect into a box.
D. Hardening rehearsal (#15 section B). The host is disposable, so the drill
applies the exact changes #16 proposes and watches what breaks: dns.mode=none
(must kill sibling resolution, must not kill egress), security.mac_filtering +
security.ipv4_filtering on the NIC (the box and its in-box Docker must keep
working), and @internal as an ACL drop destination on a bridge network (if
accepted and egress survives, #16's sibling drop is renumber-proof by
construction; if not, #16 derives the subnet instead). A FAIL in this phase is
a design veto for #16, caught before the code is written.
What it does not check
claude /login — it's interactive by design, and the box is creds-free by
design. The drill confirms Claude Code is installed and runnable; authenticating
is yours.
If the host has no /dev/kvm, claudebox falls back to container mode. The drill
still runs, but it says loudly that the VM trust boundary was not validated
rather than passing quietly on a weaker one.