Files
fips/docs/reference/cli-fips-gateway.md
Johnathan Corgan 5abf9a9325 docs: four-section /docs/ restructure with new-user content, accuracy pass, and gateway feature-set rewrite
Restructures /docs/ by reader purpose (tutorials, how-to,
reference, design), adds the new-user-progression and
operator-recipe content the prior layout lacked, runs an
accuracy pass against current source across the pre-existing
design docs, and rewrites the gateway feature-set documentation
end-to-end around its actual operational profile (a niche
feature designed for systems already serving DHCP/DNS to a
LAN, with two independent halves — outbound LAN→mesh, inbound
mesh→LAN — sharing one nftables table, one binary, and one
control socket). Top-level README and getting-started rewritten
around two equally-weighted deployment modes (overlay on
existing IP networks; ground-up over non-IP transports).

## Additions

- 11 new tutorials in docs/tutorials/: an 8-step new-user
  progression from single-daemon test-mesh peering through
  to a ground-up two-device mesh, an IPv6-adapter side-trip
  walkthrough, an Advanced Tutorials index, and a hand-held
  OpenWrt walk-through for fips-gateway deployment that
  exercises both halves of the feature.
- 12 new how-tos in docs/how-to/: firewall activation,
  Nostr discovery (resolve / advertise / open across five
  scenarios), Tor onion (directory + control_port modes),
  UDP buffer tuning, unprivileged-user setup, persistent
  identity, host aliases, Bluetooth LE peering, MTU
  diagnostics, manual Linux-host gateway deployment (covers
  both halves), gateway troubleshooting (organised by half),
  and a section index.
- 9 new reference docs in docs/reference/: configuration,
  wire formats, control-socket protocol, four CLI references
  (fips, fipsctl, fipstop, fips-gateway), security posture
  matrix, and Nostr events catalog. Configuration and
  wire-formats are renamed-and-extended from prior design/
  versions; the other seven are net-new.
- 6 new design docs: fips-concepts, fips-architecture, and
  fips-prior-work split out of the deleted fips-intro.md;
  consolidated fips-mmp and fips-mtu aggregations; and a
  new generic port-advertisement-and-nat-traversal doc
  (Nostr-signaled port advertisement plus UDP NAT-traversal
  protocol, FIPS as an example implementation, suitable for
  eventual NIP submission).
- Top-level docs/getting-started.md walking through the
  binary-installer-only Install story.
- packaging/common/hosts pre-populated with the eight public
  test-mesh nodes so shortnames resolve out of the box on
  every fresh install.

## Changes

- 23 wire-format diagrams relocated to reference/diagrams/
  alongside the wire-formats move.
- 4 design diagrams corrected against source code
  (fips-protocol-stack, fips-identity-derivation,
  fips-coordinate-discovery, fips-routing-decision).
- 10 pre-existing design docs reconciled with current
  source. Numeric corrections: stale link-MMP report bounds
  (now [1s, 5s] with 200 ms cold-start floor); UDP default
  MTU (now 1280, IPv6 minimum); node_addr formula
  (SHA-256(pubkey)[..16]); Noise patterns (IK at link, XK
  at session); peer-ACL semantics (strict allowlist requires
  ALL in peers.deny); daemon DNS upstream ([::1]:5354);
  on-the-wire bloom-filter size (1,071 bytes); obsolete
  Cargo-feature references (PR #79 dropped them) removed.
- Transport framing tightened across the docs: TCP is for
  UDP-filtered networks (not NAT traversal); Tor is a
  deployment mode (not failover); WebSocket dropped (not a
  shipped FIPS transport); WiFi promoted to Implemented via
  Ethernet in infrastructure mode; classic-Bluetooth row
  removed (BLE is the only Bluetooth-mode transport).
- docs/design/fips-gateway.md rewritten end-to-end to lead
  with the niche-feature framing and the two-halves
  structure. Title moved from "FIPS Outbound LAN Gateway"
  to "FIPS Gateway"; architecture section describes the
  common machinery (the fips-gateway service, the nftables
  table, the control socket) before splitting into separate
  "Outbound Half" and "Inbound Half" sections of equal
  weight; security considerations split per-half; no Future
  Work section (speculative directions live in the project
  tracker, not in protocol design docs). Inbound port
  forwarding is a first-class half rather than a buried
  "Implemented Extensions" subsection.
- Gateway terminology unified across all gateway docs as a
  separate Linux service running alongside the fips daemon
  (its own systemd unit / OpenWrt init script). Container-
  pattern terms (sidecar) are reserved for the
  Docker/Kubernetes sidecar deployment examples — the
  testing/sidecar/ tree, examples/k8s-sidecar/,
  examples/sidecar-nostr-relay/,
  examples/wireguard-sidecar-macos/, and the related
  CHANGELOG / top-level README entries — where the term
  carries its standard container meaning.
- Net-new design body content: rekey section in
  fips-mesh-layer (Noise IK msg1/msg2 over the established
  link, K-bit cutover, drain window, smaller-NodeAddr-wins
  tie-breaker on dual-init); Mesh Size Estimation and
  Antipoison FPR Cap sections in fips-bloom-filters;
  Mesh-Interface Query Filter subsection in
  fips-ipv6-adapter; failure-suppression knobs and clock-
  skew tolerance in fips-nostr-discovery; loop-rejection
  and mid-chain ancestor swap added to spanning-tree
  propagation / stability rules; Priority Chain in
  fips-mesh-operation renumbered to match the
  routing-decision diagram.
- Top-level README: dropped the stale nostr-discovery
  cargo-feature parenthetical. docs/README.md and the four
  section READMEs (tutorials, how-to, reference, design)
  refreshed for the new structure; index rows reflect both
  halves of the gateway feature and the new fips-gateway
  CLI reference.
- Cargo.toml [package.metadata.deb] assets path updated for
  the fips-security.md move; .gitignore /reference/ rule
  anchored to repo root so docs/reference/ is trackable.
- packaging/openwrt-ipk/files/etc/fips/fips.yaml
  configuration-doc URL updated to the new
  docs/reference/configuration.md location.

## Deletions

- docs/design/fips-intro.md (split into the three new intro
  design docs).
- docs/design/document-relationships.svg (orphan, no longer
  referenced).
- docs/proposals/ tree removed; the only proposal it
  contained (the Nostr UDP hole-punch protocol) was
  rewritten as the new generic
  design/port-advertisement-and-nat-traversal.md.
2026-05-08 03:02:12 +00:00

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Markdown

# `fips-gateway`
Long-running service that bridges a LAN segment into the FIPS mesh.
## Synopsis
```text
fips-gateway [-c FILE] [-l LEVEL]
```
## Description
`fips-gateway` runs alongside `fips` on the same host, reads the same
`fips.yaml`, and exposes two complementary functions to the LAN it
fronts:
- **Outbound (LAN -> mesh).** Allocates a virtual IPv6 from a managed
pool when a LAN client resolves `<npub>.fips`, installs nftables
DNAT/SNAT/masquerade rules so the client's traffic is rewritten and
carried into the mesh through the daemon's `fips0` adapter.
- **Inbound (mesh -> LAN).** Installs nftables DNAT and LAN-side
masquerade rules so mesh-side traffic arriving on `fips0` for the
configured listen ports is rewritten to a LAN `host:port`, per the
`gateway.port_forwards[]` block.
The service runs alongside `fips`, not as a replacement for it:
the daemon must be running on the same host with the TUN adapter
and DNS resolver enabled. The gateway is read-only with respect to the
daemon's state, and connects to the daemon's resolver only — it is
not a peer. For the architecture, see
[../design/fips-gateway.md](../design/fips-gateway.md).
`fips-gateway` is **Linux-only**. The binary errors out and exits with
status `1` on any other platform, since the NAT pipeline is built on
nftables and proxy NDP. See
[Configuration](#configuration) for the platform notes that follow
from this.
## Options
| Flag | Argument | Default | Description |
| ---- | -------- | ------- | ----------- |
| `-c`, `--config` | `FILE` | *(default search paths)* | Use `FILE` as the configuration. Skips the default search paths. |
| `-l`, `--log-level` | `LEVEL` | `info` | Tracing level: `trace`, `debug`, `info`, `warn`, `error`. Overridden by `RUST_LOG` if set (see [Environment](#environment)). |
| `-V` | — | — | Print the short version. |
| `--version` | — | — | Print the long version (short version plus build target triple). |
| `-h`, `--help` | — | — | Print usage and exit. |
## Configuration
`fips-gateway` reads the same `fips.yaml` as `fips`; the gateway is
configured under the top-level `gateway:` block. The block must
include at minimum `enabled: true`, `pool`, and `lan_interface`. For
each field — pool, LAN interface, DNS listener, conntrack overrides,
and inbound `port_forwards[]` — see the
[Gateway section](configuration.md#gateway-gateway) of the
configuration reference.
The same default search paths apply as for `fips`
(see [`fips`](cli-fips.md#files)); `-c FILE` overrides the search.
The gateway must be able to read the same configuration file the
daemon is reading, or the two will disagree about pool, DNS port,
and LAN interface.
For deployment recipes, see
[../how-to/deploy-gateway.md](../how-to/deploy-gateway.md) (manual
Linux host) and
[../tutorials/deploy-fips-gateway.md](../tutorials/deploy-fips-gateway.md)
(OpenWrt walk-through).
## Exit Codes
| Code | Meaning |
| ---- | ------- |
| `0` | Clean shutdown after `SIGINT` / `SIGTERM`. |
| `1` | Non-Linux platform, configuration load failure, missing or invalid `gateway:` block, NAT/network setup failure, or control-socket bind failure. The reason is printed to stderr or the log before exit. |
## Environment
| Variable | Description |
| -------- | ----------- |
| `RUST_LOG` | Tracing filter directive. Takes precedence over `--log-level`. Examples: `info`, `debug`, `fips=trace,fips::gateway=debug`. |
## Files
| Path | Purpose |
| ---- | ------- |
| `/etc/fips/fips.yaml` | Gateway configuration (top-level `gateway:` block). Same file the daemon reads. |
| `/run/fips/gateway.sock` | Gateway control socket. Hardcoded path; chowned to group `fips` (mode `0770`) at startup so members of that group can query without sudo. |
| `inet fips_gateway` (nftables) | NAT table the gateway installs and tears down. View with `nft list table inet fips_gateway`. |
The gateway also adds and removes a `local <pool-cidr> dev lo` route
in the local routing table so the kernel accepts pool addresses as
locally-owned.
## Control Socket
`fips-gateway` exposes a JSON line-protocol control socket separate
from the daemon's. The command set (`show_gateway`, `show_mappings`)
and JSON shapes are documented in the
[Gateway Command Catalog](control-socket.md#gateway-command-catalog).
There is no `fipsctl` subcommand for the gateway — query the socket
directly with `nc -U`, or watch the **Gateway** tab in
[`fipstop`](cli-fipstop.md), which polls the gateway socket
automatically.
## See also
- [`fips`](cli-fips.md) — the daemon. Required to be running on the
same host.
- [`fipstop`](cli-fipstop.md) — the live-status TUI; its Gateway tab
polls the gateway control socket.
- [configuration.md § Gateway](configuration.md#gateway-gateway) —
full `gateway.*` block reference.
- [control-socket.md § Gateway Command Catalog](control-socket.md#gateway-command-catalog)
— wire protocol for the gateway socket.
- [../design/fips-gateway.md](../design/fips-gateway.md) — design,
NAT pipeline, virtual IP pool lifecycle.
- [../how-to/deploy-gateway.md](../how-to/deploy-gateway.md) — manual
Linux deployment.
- [../how-to/troubleshoot-gateway.md](../how-to/troubleshoot-gateway.md)
— diagnostic recipes.
- [../tutorials/deploy-fips-gateway.md](../tutorials/deploy-fips-gateway.md)
— OpenWrt walk-through.