fips/docs/reference/control-socket.md

Control Socket Protocol

The FIPS daemon and fips-gateway each expose a local control socket that accepts line-delimited JSON requests and returns line-delimited JSON responses. fipsctl and fipstop are clients of this protocol; operators can also drive it directly with any tool that can speak length-bounded JSON over a stream socket.

Connection

Linux / macOS

A Unix domain socket. The default path is resolved in this order:

1. /run/fips/control.sock (or /run/fips/gateway.sock for the gateway), if /run/fips exists. This is what the fips.service systemd unit creates.
2. $XDG_RUNTIME_DIR/fips/control.sock otherwise.
3. /tmp/fips-control.sock if neither of the above is available.

The daemon chowns the socket file and its parent directory to the fips group at bind time and sets mode 0770. Members of the fips group can therefore connect without root. Add a user with sudo usermod -aG fips $USER (re-login required).

The path can be overridden at the daemon side via node.control.socket_path in the YAML config, and at the client side via fipsctl -s PATH or fipstop -s PATH.

Windows

A TCP listener bound to 127.0.0.1. The daemon's port is 21210 by default; the gateway's is 21211. Only loopback connections are accepted. Override via node.control.socket_path (which takes a port number string on Windows).

Windows TCP does not provide filesystem-level ACLs — any local user can connect. See the security note in configuration.md.

Request Format

One JSON object per line, terminated by \n. Maximum request size is 4096 bytes; longer requests are dropped with request too large.

{"command": "<name>", "params": {<object>}}

Field	Type	Required	Description
command	string	yes	Command name. See Daemon command catalog and Gateway command catalog.
params	object	only for commands that take parameters	Parameter object. Unknown fields are ignored; missing required fields produce an error response.

Unknown top-level fields in the request are silently ignored.

Response Format

One JSON object per line.

{"status": "ok", "data": {<object>}}
{"status": "error", "message": "<reason>"}

Field	Type	When present
status	string	always; one of "ok" or "error".
data	object	on ok responses.
message	string	on error responses.

I/O timeouts

The daemon enforces a 5-second timeout for both the request read and the response write. If the connection idles longer than that, the daemon closes it with no response.

Common error messages

Message	Cause
empty request	Connection closed before a newline was received.
invalid request: <serde error>	Malformed JSON or missing command.
request too large	Request exceeded 4096 bytes.
read timeout / read error: ...	Slow client or transport failure.
unknown command: <name>	Command not registered with this daemon.
missing params for <name>	Command requires params but none were provided.
missing '<field>' parameter	Required parameter missing.
query timeout	Internal handler did not respond within 5 seconds.
node shutting down	Daemon is exiting.
gateway not yet initialized	(Gateway socket only) snapshot has not been published yet.

Daemon Command Catalog

Read-only queries are dispatched in src/control/queries.rs; mutating commands are dispatched in src/control/commands.rs. The table below lists every command currently registered.

Read-only queries

Command	Params	data shape (top-level keys)
show_status	—	version, npub, node_addr, ipv6_addr, state, is_leaf_only, is_root (bool — this node is the spanning-tree root), root (hex node-addr of the current tree root), persistent (bool — identity is persisted, i.e. persistent set or an nsec configured), peer_count, session_count, link_count, transport_count, connection_count, transport_peer_counts (object mapping transport-type name to its connected-peer count; configured transports appear with 0), tun_state, tun_name, effective_ipv6_mtu, control_socket, pid, exe_path, uptime_secs, estimated_mesh_size, forwarding, sparklines.
show_acl	—	allow_file, deny_file, enforcement_active, effective_mode, default_decision, allow_all, deny_all, allow_file_entries, deny_file_entries, allow_entries, deny_entries.
show_peers	—	peers[] — per-peer object: node_addr, npub, display_name, ipv6_addr, connectivity, link_id, direction, transport_addr, transport_type, is_parent, is_child, tree_depth, effective_depth (tree_depth + link_cost — the metric evaluate_parent ranks on; null when the peer has no coords, or is unmeasured while another peer has an SRTT sample, per the cold-start gate), stats, noise, current_k_bit, mmp, plus optional nostr_traversal, rekey_in_progress, rekey_draining.
show_links	—	links[] — link_id, transport_id, remote_addr, direction, state, created_at_ms, stats.
show_tree	—	my_node_addr, root, root_npub (bech32 npub of the current tree root), is_root, depth, my_coords[], parent, parent_display_name, declaration_sequence, declaration_signed, peer_tree_count, peers[], stats.
show_sessions	—	sessions[] — remote_addr, npub, display_name, state (established, initiating, awaiting_msg3, unknown), is_initiator, last_activity_ms, stats, optional mmp, current_k_bit, is_draining.
show_bloom	—	own_node_addr, is_leaf_only, sequence, leaf_dependent_count, leaf_dependents[], peer_filters[], uptree_fill_ratio (fill ratio of the last filter actually sent to the tree parent), uptree_estimated_count (cardinality estimate of that uptree filter — this node's whole subtree under split-horizon, not the mesh; both are null for a root node or before the first announce), stats.
show_mmp	—	peers[] (link-layer per peer), sessions[] (session-layer per session). Each entry includes loss/RTT/ETX/goodput, smoothed values, trends.
show_cache	—	count, max_entries, fill_ratio, default_ttl_ms, expired, avg_age_ms, entries[] — per-destination coords, depth, age, last-used, optional path_mtu.
show_connections	—	connections[] — pending handshakes: link_id, direction, handshake_state, started_at_ms, idle_ms, resend_count, optional expected_peer.
show_transports	—	transports[] — transport_id, type, state, mtu, name, local_addr, optional tor_mode, onion_address, tor_monitoring, stats.
show_routing	—	coord_cache_entries, identity_cache_entries, pending_lookups[], pending_tun_destinations, pending_tun_packets, recent_requests, retries[], forwarding, discovery (request/response sub-counters; includes req_deduplicated — requests suppressed as recent duplicates — and req_dedup_cache_full — requests admitted because the dedup cache was full), error_signals, congestion.
show_identity_cache	—	entries[], count, max_entries. Each entry: node_addr, npub, display_name, ipv6_addr, last_seen_ms, age_ms.
show_listening_sockets	—	fips0_addr, firewall_active (bool — inet fips table loaded), sockets[]. Each entry: proto (tcp / udp), local_addr (:: or the node's fd00::/8 address), port, pid (nullable), process (nullable), wildcard_bind (bool — local_addr == ::), filter (accept / drop / unknown / no_firewall). Linux-only; returns an empty sockets[] on other platforms.
show_stats_list	—	metrics[] (each with name, unit, scope), fast_ring_seconds, slow_ring_minutes, peer_retention_seconds.
show_metrics	—	Flat snapshot of every counter family in the metrics registry: forwarding, discovery, tree, bloom, congestion, errors. Each value is that family's counter snapshot object. Counter-only — gauges/histograms that need the live node are excluded. Served off the main loop. Silent-rejection sites classify their reason as a typed RejectReason and increment the matching per-family counter exposed here — see Rejection reasons.
show_stats_history	metric (req), peer (req for per-peer metrics), window (<N>s / <N>m / <N>h, default 10m), granularity (1s / 1m, default 1s)	A single Series: metric, unit, granularity_seconds, values[].
show_stats_all_history	peer (optional npub), window, granularity	granularity_seconds, window_seconds, peer, series[] (one per metric).
show_stats_peers	—	peers[], count. Each entry: npub, node_addr, display_name, is_active, first_seen_secs_ago, last_contact_secs_ago.
show_stats_history_all_peers	metric (req per-peer name), window, granularity	metric, unit, granularity_seconds, window_seconds, peers[] (each with node_addr, display_name, is_active, values[]).

The schema of each query response is pinned by snapshot tests in src/control/snapshots/; intentional schema changes regenerate those fixtures.

Rejection reasons

Silent-rejection paths across the node classify why a message was dropped via a typed RejectReason rather than only logging it, so the what of a rejection is visible in the counter snapshots above. The top-level reason set has eight families, mirroring the protocol-layer / subsystem split of the metrics:

• Tree — spanning-tree TreeAnnounce processing rejections.
• Bloom — bloom-filter FilterAnnounce processing rejections.
• Discovery — discovery request / response processing rejections.
• Handshake — Noise handshake state-machine rejections.
• Session — FSP session state-machine rejections.
• Mmp — MMP link-layer rejections.
• Forwarding — forwarding-path rejections (no-route, TTL, MTU).
• Transport — transport-layer rejections (admission caps, framing).

Each rejection increments the corresponding counter in its family's stats, surfaced through show_metrics (the tree, bloom, discovery, and forwarding families carry their own counters; the errors family and the remaining subsystem counters carry the rest). The full per-family variant list lives in src/node/reject.rs; it is not reproduced here to avoid duplicating the source.

Mutating commands

Command	Required params	Behaviour
connect	npub (bech32), address (transport endpoint), transport (udp, tcp, tor, nym, ethernet)	Asks the node to dial the peer over the named transport. The named transport must be configured and running. Returns the API result on success or an error string on failure.
disconnect	npub (bech32)	Asks the node to drop the link to the named peer.

Both commands run on the daemon's main task and may block briefly while the node mutates its state.

Profiler toggle (--features profiling builds only)

Command	Params	Behaviour
profile_tick_on	dir (optional directory path; default /var/log/fips)	Creates the capture file, publishes its path, and starts the writer thread. data: state, path, interval_secs, byte_cap. Errors if a capture is already running (naming the active file) or the directory is unwritable.
profile_tick_off	—	Stops the capture, drains once more, joins the writer. data: state, stopped, stopped_by_cap, stopped_by_error, path, bytes.
profile_tick_status	—	data: state (idle / running / stopped_by_cap / stopped_by_error), path, bytes, byte_cap, interval_secs.

Unlike connect and disconnect, these three are served in the control accept task rather than on the daemon's main task. All of their state is process statics and none of them needs &mut Node, so routing them through the main loop would only make the toggle queue behind the tick body it exists to measure. They are absent from a default build, where the daemon answers them as unknown commands.

Gateway Command Catalog

fips-gateway exposes a separate control socket with its own command set. Dispatch lives in src/gateway/control.rs.

Command	Params	data shape
show_gateway	—	pool_total, pool_allocated, pool_active, pool_draining, pool_free, nat_mappings, dns_listen, uptime_secs, pool_cidr, lan_interface, dns_upstream, dns_ttl, pool_grace_period.
show_mappings	—	mappings[] — virtual_ip, mesh_addr, node_addr, dns_name, state (Allocated, Active, Draining), sessions, age_secs, last_ref_secs.

Until the first snapshot has been published (very early in startup), both commands return gateway not yet initialized.

Driving the Socket Directly

# Linux / macOS
echo '{"command":"show_status"}' | sudo nc -U /run/fips/control.sock

# Windows (PowerShell with a TCP-capable tool of your choice)

The newline at the end of the request is required: the daemon reads one line per connection. The connection is closed after the single response is written.

See also

• fipsctl — full-featured client.
• fipstop — read-only TUI.
• configuration.md — node.control.* keys.