housecarl/docs/api.md

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 has what each call needs.

Errors

{"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
422	validation	the change would make the configuration invalid; problems lists why (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:

{"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.
• ?dry_run=1 checks the change, with nftables too, and returns what it would do, with "applied": false, "dry_run": true.
• 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": true, "version"}, without authentication
GET /status	build, started, 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 /ruleset	the nftables ruleset Housecarl builds, as text
GET /counters	{"since", "counters": {"r12": {"packets", "bytes"}, ...}}, by mark (design.md); totals since housecarld started
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). 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:

{"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:db8:7f3d::/48"], "antispoof_v4": ["10.0.0.0/8", "..."], "antispoof_v6": ["fc00::/7", "..."],
 "flowtable_devices": ["wan", "enp2s0"], "probation_seconds": 120}

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}	create; rules, forwards and NAT rules go last unless given a position
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 /{kind}/{ref}/move	{"before": ID}, {"after": ID} or {"to": "start"|"end"}; a rule can take "chain" too

The objects:

{"name": "lan", "interfaces": ["enp2s0", "enp2s0.*"], "external": false, "comment": ""}
{"name": "trusted", "entries": ["10.0.10.0/24", "2001:db8:7f3d:10::/64"], "dynamic": false, "timeout": 0, "comment": ""}
{"name": "jellyfin", "entries": ["tcp/8096", "tcp/8920"], "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, "per": "minute", "burst": 5, "over": true, "per_source": true}, "conn_limit": 0,
 "action": "drop", "reject_with": "", "log": true, "log_prefix": "",
 "raw": "", "comment": "", "disabled": false}
{"name": "jellyfin", "protocols": ["tcp"], "ports": "8096", "public_addresses": ["203.0.113.7"], "sources": [],
 "to": "10.0.10.57", "to_port": "443", "to6": "2001:db8:7f3d:10::57", "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).

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); 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
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", "replace": false} (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

Certificate

Administrators only (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=]