# The REST API

Everything the web UI and the CLI do goes through this API, under
`/api/v1`. Requests and answers are JSON.

## Authentication

* **API tokens**: `Authorization: Bearer housecarl_...`. Make one in the
  web UI (your account), with `hc token create NAME`, or with `housecarld
  user token USER NAME` on the server.
* **Sessions**: `POST /auth/login` with `{"username", "password"}` sets a
  cookie and returns `csrf_token`. Requests other than GET must send it as
  `X-CSRF-Token`.
* **The local socket** (`/run/housecarl/housecarl.sock`): root and
  housecarld's own user need nothing; others send a token. Changes made
  through it aren't on probation.

Failed logins and token attempts are rate limited per address and per
user name. [permissions.md](permissions.md) has what each call needs.

## Errors

```json
{"error": {"code": "validation", "message": "rule input #31: there is no set trusted",
           "problems": [{"severity": "error", "code": "unknown_set", "message": "from: there is no set trusted", "object": "rule input #31"}]}}
```

| Status | Code | |
|---|---|---|
| 400 | `bad_request` | the request can't be read |
| 401 | `unauthenticated`, `session_expired`, `login_failed` | |
| 403 | `forbidden`, `csrf` | |
| 404 | `not_found` | |
| 409 | `conflict` | e.g. undoing a change after the objects changed again; a takeover or closing connections in shadow mode ([shadow.md](shadow.md)) |
| 422 | `validation` | the change would make the configuration invalid; `problems` lists why ([validation.md](validation.md)) |
| 422 | `firewall` | nftables refused the ruleset (`nft -c`), or applying it failed; the message has nftables' words. Nothing was changed |
| 429 | `rate_limited` | |

## Changes

Calls that change the configuration answer:

```json
{"applied": true, "history_id": 7,
 "changes": [{"kind": "rule", "id": 31, "label": "input #31 (SSH from home)", "after": {...}}],
 "warnings": [{"severity": "warning", "code": "set_empty", "message": "...", "object": "..."}],
 "object": {...},
 "confirm_by": "2026-10-19T10:02:00Z"}
```

* `confirm_by`: the change is on probation, and is rolled back at that
  time unless `POST /confirm` comes first. Missing for changes made
  through the socket, and in shadow mode ([shadow.md](shadow.md)).
* `confirm_token`: the client that made the change can confirm it by
  itself with `POST /confirm {"token"}`, from the same address, as the
  same user and token, over a new connection (the answer closes this
  one). Missing when a person must confirm (`manual_confirm`).
* `?dry_run=1` checks the change, with nftables too, and returns what it
  would do, with `"applied": false, "dry_run": true`, and `diff`: the
  ruleset's unified diff.
* `?changeset=ID` (or the header `X-Housecarl-Changeset: ID`) stages the
  change in that changeset instead ([Changesets](#changesets)): the answer
  has `"staged": true`, `changes` (this operation's) and `changeset`.
* `before` is missing for a create and `after` for a delete.
* `warnings` are the problems the change brings; older ones are in
  `/status`.
* `object` is the created or changed object.

Creating answers 201, other changes 200.

## Endpoints

### Status

| | |
|---|---|
| `GET /healthz` | `ok`, `version`, `firewall` (`applied`, `unconfigured`, `fallback`, `missing`), `mode` (`enforcing`, or `shadow`: the ruleset blocks nothing, [shadow.md](shadow.md)), `probation` (changes waiting to be confirmed), `warnings` (codes); HTTP 503 unless `ok`. Without authentication; read at most every five seconds ([operations.md](operations.md#monitoring)) |
| `GET /status` | `build`, `started`, `mode` (`enforcing` or `shadow`), `shadow_position` (`after` or `before`, in shadow mode), `applied` (the ruleset is in force), `apply_error`, `problems`, `probation`, `interfaces`, `counts` (objects by kind), `other_tables` (other nftables tables, `"inet main"`) |
| `GET /interfaces` | the machine's interfaces: `name`, `up`, `addresses`, `zone` |
| `GET /matrix[?changeset=ID]` | the zone matrix: `zones`, `cells` (`from`, `to` (a zone, or `firewall`), `chain`, `summary` (allowed, blocked, partly), `verdict` (what the rest gets: allowed, blocked), `decided_by`, `rule_id`, `hits`, `allowed` and `blocked` (exceptions by verdict), `open` (what the allowing exceptions let through, in short), `same_zone` and `note`, `exceptions`: `rule_id`, `chain`, `label`, `verdict` (allowed, blocked, logged, unknown), `what`, `short`, `hits`). `hits` are the rule's or policy's packets since housecarld started, all its traffic (missing: no counter) ([rules.md](rules.md#the-zone-matrix)) |
| `GET /ruleset[?enforcing=1]` | the nftables ruleset Housecarl builds, as text. In shadow mode it is the shadow ruleset; `enforcing=1` gives the one loaded once shadow mode is off |
| `GET /counters` | `{"since", "counters": {"r12": {"packets", "bytes"}, ...}}`, by mark ([design.md](design.md#its-own-table-only)); totals since housecarld started |
| `GET /quotas` | each rule's quota: `rule_id`, `rule`, `quota`, `used` (bytes), `addresses` (`[{"address", "used"}]` for a per-address quota), `last_reset`, `next_reset` |
| `GET /connections[?q=&limit=]` | tracked connections: `family`, `protocol`, `source`, `source_port`, `destination`, `destination_port` (or `icmp_id`, `icmp_type`, `icmp_code`), `dnat_to`, `dnat_port`, `snat_to`, `state`, `assured`, `timeout` (seconds left), `packets` and `bytes` when the kernel counts them. `q`: all of its words in the addresses, `:port`, protocol, state |
| `POST /names` | `{"addresses": [...]}` (at most 2000): `{"enabled", "names": {"192.168.1.20": "laptop.example.net"}}`, the names of the inside addresses among them, by reverse lookup ([configuration.md](configuration.md#names)). Addresses without a name, outside ones, and those still being looked up after a second are left out; ask again for those. `log:read` |
| `POST /connections/close` | `{"connections": [...]}` (as listed) or `{"search": "192.168.1.50"}`: delete their tracking entries (`config:write`, audited); answers `{"closed": N}`. 409 in shadow mode |
| `POST /trace` | `{"address", "port", "protocol", "seconds"}` (5-600, default 60): start tracing (`config:write`, audited); 409 while one runs |
| `GET /trace` | the trace running, or the last: `running`, `input`, `started`, `ends`, `error`, `packets`: each with `time`, `in`, `out`, `protocol`, addresses and ports, `tcp_flags`, `icmp_type`, `steps` (`table`, `chain`, `kind` rule or policy, `rule`, `mark`, `label`, `verdict`), `verdict` (accepted, dropped) and `decided_by`; in shadow mode `would_drop`, the step where Housecarl would have dropped it |
| `DELETE /trace` | stop it |
| `GET /log[?limit=&after=&q=]` | logged packets, newest first: `time`, `prefix`, `in`, `out`, `family`, `protocol`, `source`, `source_port`, `destination`, `destination_port`, `icmp_type`, `tcp_flags`, `length`, `mark` (the rule's), `verdict`, `shadow` (logged in shadow mode: a drop or reject is what would have been done). `after` (a time) for those since; `q` searches |
| `GET /catalog` | built-in services, chains, actions, roles, the log group |

### Settings

`GET /settings`, `PATCH /settings` with any of:

```json
{"input_policy": "drop", "forward_policy": "drop", "output_policy": "accept",
 "log_policy_drops": false,
 "builtins": {"loopback": true, "established": true, "drop_invalid": true, "icmpv6": true,
              "ping_internal": true, "dhcpv6_client": true, "antispoof": true, "mss_clamp": false},
 "own_prefixes": ["2001:db8::/48"], "antispoof_v4": ["10.0.0.0/8", "..."], "antispoof_v6": ["fc00::/7", "..."],
 "flowtable_devices": ["wan", "eth1"], "probation_seconds": 120, "manual_confirm": false,
 "stats_per_device": false}
```

Lists replace the old ones. `probation_seconds` 0 is the default (120).

### Objects

Zones, sets, services, rules, port forwards, source NAT and redirects
share one pattern, `/{kind}` with kind `zones`, `sets`, `services`,
`rules`, `forwards`, `snats` or `redirects`:

| | |
|---|---|
| `GET /{kind}` | all of them, in order; `GET /rules?chain=input` for one chain; `GET /services` includes the built-in ones |
| `POST /{kind}[?before=ID\|after=ID\|first=1]` | create; rules, forwards and NAT rules go last unless given a `position`, or placed before or after another of their chain, or first, in the same change (one history entry; staged in a changeset, the place goes with it) |
| `GET /{kind}/{ref}` | by ID, or name for zones, sets, services and forwards |
| `PATCH /{kind}/{ref}` | change the fields given (a JSON merge: `null` clears) |
| `DELETE /{kind}/{ref}` | refused while something uses it |
| `POST /rules/{ref}/reset-quota` | start a rule's quota again now (`config:write`; audited, not staged). Optional body: `{"address": "192.168.1.23"}` starts only that address's again (a per-address quota; an IPv6 address counts for its /64; 404 if it hasn't used the quota); `{"give": 5368709120}` takes that many bytes off what was used instead (the address's, or every address's), until the next reset |
| `POST /{kind}/{ref}/move` | `{"before": ID}`, `{"after": ID}` or `{"to": "start"\|"end"}`; a rule can take `"chain"` too |

The objects:

```json
{"name": "lan", "interfaces": ["eth1", "eth1.*"], "external": false, "comment": ""}
{"name": "trusted", "entries": ["192.168.1.0/24", "2001:db8:1::/64"], "dynamic": false, "timeout": 0, "comment": ""}
{"name": "web", "entries": ["tcp/8080", "tcp/8443"], "comment": ""}
{"chain": "input",
 "in_zones": ["wan"], "not_in": false, "out_zones": [], "not_out": false,
 "sources": ["trusted"], "not_sources": false, "destinations": [], "not_destinations": false,
 "services": ["ssh"], "family": "",
 "ct_state": ["new"], "ct_status": [], "days": [], "hour_from": "", "hour_to": "",
 "limit": {"rate": 3, "unit": "", "per": "minute", "burst": 5, "over": true, "per_source": true, "per_destination": false}, "conn_limit": 0,
 "quota": {"bytes": 53687091200, "over": true, "per_source": true, "per_destination": false, "reset": "monthly", "day": 15},
 "group_v4": 0, "group_v6": 0,
 "action": "drop", "reject_with": "", "log": true, "log_prefix": "",
 "raw": "", "comment": "", "disabled": false}
{"name": "web", "protocols": ["tcp"], "ports": "8443", "public_addresses": ["203.0.113.10"], "sources": [],
 "to": "192.168.1.10", "to_port": "443", "to6": "2001:db8:1::10", "hairpin": true, "hairpin_sources": [],
 "comment": "", "disabled": false}
```

A source NAT rule is a match (as a rule's, without the rule's other
fields) with `"to"` (empty: masquerade), a redirect a match with
`"to_port"`. Times are seconds (`timeout`).

### Statistics

`GET /stats/status`, `/stats/summary`, `/stats/timeline`, `/stats/top`,
`/stats/hits` and `/stats/heatmap` (`log:read`): see
[stats.md](stats.md#the-api).

### Changesets

Changes staged to be reviewed and applied together ([design.md](design.md#reviewing-changes-changesets)).

| | |
|---|---|
| `GET /changesets[?status=open&mine=1&limit=]` | newest first |
| `POST /changesets` | `{"description"}`; answers the changeset (201) |
| `GET /changesets/{id}` | `{"id", "username", "via", "description", "status": "open"\|"applied"\|"discarded", "ops": [{"seq", "op", "kind", "ref", "id", "data", "summary", "added_at"}], "created_at", "updated_at", "history_id"}` |
| `PATCH /changesets/{id}` | `{"description"}` |
| `GET /changesets/{id}/preview` | `{"valid", "changes", "warnings", "error", "diff"}`: what applying it would do; `error.op` names an operation that no longer applies |
| `POST /changesets/{id}/apply` | optional `{"description"}`; answers like a change, with `confirm_by` over the network and `changeset` |
| `POST /changesets/{id}/discard` | |
| `DELETE /changesets/{id}/ops/{seq}` | take one operation out |

Staging (`?changeset=ID` on any change to objects or settings) checks
the changeset with the new operation, and nftables checks its ruleset;
an error refuses the operation. Only open changesets take operations, and
only their owner's (or an administrator's). An undo
(`POST /history/{id}/revert?changeset=ID`) is staged as one operation,
which checks when it is replayed that nothing it touches changed since;
applied, History links it to the entry it undoes. `/import/nft` and
`/takeover` can't be staged: with a changeset named they answer 400.

Reads of objects, settings and `/ruleset` with `?changeset=ID` show the
configuration as the changeset will make it; objects are marked
`"pending": "new"`, `"changed"` or `"deleted"` (deleted ones stay in the
list). A changeset that no longer applies shows the current
configuration, with the reason in the `X-Housecarl-Changeset-Error`
header.

### Dynamic sets' entries

| | |
|---|---|
| `GET /sets/{name}/elements` | `[{"address", "timeout"}]`, `timeout` the seconds left |
| `POST /sets/{name}/elements` | `{"address": "10.0.30.17", "timeout": 3600}`; `timeout` 0 is the set's |
| `DELETE /sets/{name}/elements/{address}` | |

These need `sets:read` or `sets:write`, for that set
([permissions.md](permissions.md)); they aren't on probation or in the
history, but are audited.

### Probation

| | |
|---|---|
| `GET /probation` | `{"pending": [history IDs], "takeovers": N, "deadline", "seconds_left"}` |
| `POST /confirm` | keep them: `{"confirmed": N}`; the ruleset is saved for the boot. With `{"token"}`, the client confirming its own change (see `confirm_token`): 409 if a newer change is pending, or over the change's own connection; 403 from another user or address |
| `POST /rollback` | undo them now |

### History, import, takeover

| | |
|---|---|
| `GET /history[?limit=&before=]` | changes, newest first |
| `GET /history/{id}` | one, with each object before and after |
| `POST /history/{id}/revert` | undo it; 409 if an object it touched has changed since, or it was undone already |
| `POST /import/nft` | `{"json": NFT_JSON, "text": "nft -a list ruleset output", "defines": "ruleset file", "table": "inet main", "zones": {"enp2s0": "lan"}, "replace": false}` ([import.md](import.md)); answers with `state` (the imported configuration), `notes` and `raw` too |
| `POST /takeover` | `{"tables": ["inet main"]}`: delete these tables (administrators); on probation over the network; 409 in shadow mode |

### Certificate

Administrators only ([certificates.md](certificates.md)).

| | |
|---|---|
| `GET /certificate` | `{"configured", "source": "acme"\|"file"\|"none", "status": {"domain", "directory", "staging", "state": "none"\|"ok"\|"working"\|"error", "not_before", "not_after", "issuer", "renew_at", "last_error", "last_attempt", "next_attempt", "check"}}` |
| `POST /certificate/check` | run the check now (up to a few minutes); answers `{"time", "domain", "ok", "steps": [{"name", "status", "detail", "queries"}]}` |
| `POST /certificate/renew` | get a new certificate now, in the background (202); follow it with `GET /certificate` |

### Users, tokens, audit

| | |
|---|---|
| `POST /auth/login`, `POST /auth/logout`, `GET /auth/whoami` | `whoami` has `token_id` when the caller uses a token |
| `POST /me/password` | `{"current", "password"}` |
| `GET /me/tokens`, `POST /me/tokens` | `{"name", "role", "grants", "expires_in"}`; the answer's `secret` is shown once |
| `GET /tokens`, `DELETE /tokens/{id}` | all tokens (administrators), revoke |
| `POST /tokens/{id}/rotate` | a new secret: `{"grace": "1h", "expires_in": "90d", "no_expiry": false}`, all optional; answers with `secret` and `previous_secret_valid_until` |
| `GET`, `POST /users`; `PATCH`, `DELETE /users/{id}` | administrators; `{"username", "password", "admin", "role", "grants", "disabled", "comment"}` |
| `GET`, `POST /users/{id}/tokens` | |
| `GET /audit[?user=&action=&result=&q=&before=&limit=]` | |