0429a11020
incus-user confines an incus-group user to their own project, but its
defaults miss box's contract three measured ways (Debian 13 / Incus 6.0.4):
a private UNHARDENED NAT bridge per user (ipv6.nat=true, no ACL, no DNS
isolation), snapshots blocked, and the box-net profile invisible to their
project. So the tier is an admin-run idempotent convergence:
box grant <user> # incus group; touch incus-user (the project is lazy);
# drop the private-bridge eth0 from their default
# profile; restricted.networks.access=boxnet — and ONLY
# boxnet, or the unhardened bridge stays one --network
# flag away; restricted.snapshots=allow; install the
# shipped box-net profile into their project
box revoke <user> # group removal closes the socket, boxes keep running
--purge # ...or delete their world, and assert the absence
box_tier() (live credentials, argless id -nG; byte-identical copy in
setup-host.sh) drives the tier-aware surface: new pre-flights the profile
and names the right fix per tier, expose refuses before any daemon call
(without the guard the failure is a lie — restricted certs cannot read
boxnet's redacted config, so box_net_ip claims a running box has no
address), setup-host exits 0 with the honest note, doctor judges only what
the caller can see.
Also fixed while the rehearsal exercised the lifecycle: box restore
dispatched 'incus restore', which does not exist in Incus 6 (it is
'incus snapshot restore') — the verb had never worked. Fixed for every tier.
Convergence survives incus-user restarts by that tool's own design (it
configures a project only at creation) — read in its source, then measured.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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|---|---|---|
| .. | ||
| doctor.sh | ||
| drill.sh | ||
| README.md | ||
| RUNS.md | ||
| wipe.sh | ||
The drill
An end-to-end rehearsal of box 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.
Something wrong with the host? bash drill/doctor.sh — it reports whether
the host is fit to drill (network, profile, ACL, leftover boxes, whether a box
can still resolve DNS), and --fix reverts what an aborted run left behind.
The drill mutates the host in phase D; an aborted run can leave a network that
mints boxes with no DNS.
Iterating on the drill? Read RUNS.md first — it is the run log: what the audit has answered so far, the bugs the drill has found in box, the traps this script has already fallen into (every one cost a run), how to diagnose a stall, and how to run a single probe by hand instead of paying for a whole run.
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 box 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
box 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
agent login (e.g. claude /login) — it's interactive by design, and the box is
creds-free by design. The drill confirms each coding-agent template's CLI is
installed and runnable; authenticating is yours.
If the host has no /dev/kvm, box 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.