branderson
ed2a843406
Alerts now name the kind of change and the watched area it falls under, from a fixed list, and report lists each path as added, modified or removed. ignore_paths keeps a change in the report without alerting on it. dejima-guard expect opens a window that holds change and unreachable alerts, then accepts at its end. Critical paths and containment still alert, and a window never accepts a critical path. accept now runs a check afterwards so the heartbeat resumes, status summarises the guard's state, and bin/dejima-guard-docker runs any command in the container from any directory.
120 lines
5.4 KiB
YAML
120 lines
5.4 KiB
YAML
# The guard, as one service.
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#
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# AN EXAMPLE, not a compose file. Copy it to docker-compose.yml, edit it there,
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# and start that - the copy is gitignored so your host and your URLs do not end
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# up in a commit.
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#
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# Do not use it as an override. `docker compose up` reads docker-compose.yml
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# and docker-compose.override.yml together and merges them, so an override
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# leaves these example values in play rather than replacing them.
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#
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# As written it will not start: the host below is a placeholder the guard
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# refuses, so this can never become a live config by being copied and
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# forgotten.
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services:
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dejima-guard:
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# Built here, not pulled: there is no registry for this. Which makes
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# `--build` part of every command that starts it - `docker compose up -d`
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# alone reuses the image it already has, so after a `git pull` it would run
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# the old code and look like it had worked.
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build: .
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# image: gitbox.example.invalid/dejima/dejima-guard:latest
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container_name: dejima-guard
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# bin/dejima-guard-docker finds the container by this name. And an init,
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# because `dejima-guard expect` leaves a process waiting for the window's
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# end, which needs reaping once it is done.
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init: true
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restart: unless-stopped
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environment:
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# --- the machine being WATCHED, not the one this runs on ------------
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#
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# The devbox's hostname or address, as this container reaches it.
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# Replace the placeholder: the guard refuses to start on CHANGE-ME.
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DEJIMA_GUARD_DEVBOX_HOST: CHANGE-ME.example.invalid
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# The account ON THE DEVBOX to log in as. Not root, and there is no
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# default: the devbox runbook builds a machine with no root password
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# and expects sudo from an ordinary account. The guard connects as that
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# account and elevates for the two commands it runs.
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DEJIMA_GUARD_DEVBOX_USER: your-devbox-account
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# The private key, inside this container, to connect with. Mounted as a
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# secret below rather than baked into the image.
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DEJIMA_GUARD_SSH_KEY: /run/secrets/guard_key
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# Where the devbox's host key is remembered. On the state volume,
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# because a container filesystem is new every run - and without it,
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# every collection fails host-key verification and reports the devbox
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# unreachable. Already set in the image; here so it is visible.
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DEJIMA_GUARD_SSH_KNOWN_HOSTS: /var/lib/dejima-guard/known_hosts
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# --- where alerts go -----------------------------------------------
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#
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# Its OWN ntfy topic, not the one dejima pushes to. That URL lives on
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# the devbox, so root there can publish to it: a compromised box could
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# drown the topic or forge an all-clear. The token for this one goes in
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# the mounted config, not here.
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DEJIMA_GUARD_NTFY_URL: https://ntfy.example.invalid/devbox-alerts
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# --- the dead-man's switch ------------------------------------------
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#
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# NOT HERE. heartbeat_url goes in the mounted config beside ntfy_token,
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# because an Uptime Kuma push URL carries its token in the path: the URL
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# is the credential rather than the destination. `docker inspect` shows
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# everything in this block, and so does anything that can read /proc.
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#
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# What it grants is worth being plain about. Anyone holding that URL can
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# tell Kuma this guard is healthy, which suppresses the one signal that
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# reports a guard that has died - the single channel a compromised devbox
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# cannot reach.
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# --- this container --------------------------------------------------
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#
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# Seconds between collections. Sets the dead-man's switch granularity
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# and how long an intruder has to notice the monitoring and scrub.
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DEJIMA_GUARD_INTERVAL: "900"
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# The name of the machine this container runs on, so an alert says
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# where to go and run `dejima-guard report`. Optional.
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# DEJIMA_GUARD_GUARD_NAME: your-docker-host
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# Anything secret goes in the config file rather than here. Everything
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# above is visible in `docker inspect` and to anything that can read
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# /proc; a mounted secret is not. The guard reads the environment first
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# and the file second, so this is the value that overrides.
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DEJIMA_GUARD_CONF: /run/secrets/guard_config
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# Mounted at /run/secrets/<name>, which is why CONF points there rather
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# than at /etc. A `target:` naming an absolute path is a swarm feature and
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# does not do what it looks like it does under plain `docker compose`.
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secrets:
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- guard_key
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- guard_config
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volumes:
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# The baseline, the last report, and known_hosts. Losing this is not a
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# clean slate: it is a guard that compares clean against everything and
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# cannot verify the host it connects to.
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- guard-state:/var/lib/dejima-guard
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# It opens two outbound connections and writes one directory. Nothing here
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# is a hardship, and this container holds an SSH key to a machine whose
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# threat model says it may be owned.
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read_only: true
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tmpfs:
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- /tmp
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cap_drop: [ALL]
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security_opt:
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- no-new-privileges:true
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# NO PORTS. Not "none needed today" - the reason a container is an
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# acceptable home for this is that nothing can connect to it.
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volumes:
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guard-state:
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secrets:
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guard_key:
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file: ./secrets/guard_key # mode 0600, the private key
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guard_config:
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file: ./secrets/config # ntfy_token, and anything else secret
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