Files
fips/docs/how-to/enable-nostr-discovery.md
T
Johnathan Corgan 6a564e26ac Prepare the v0.5.0 release content
Everything the release needs except the version number, which stays at
0.5.0-dev until the tag.

The changelog entry covers only the work that is new on this line. The
point release's forty-six entries arrived under their own heading with the
forward merge and are left alone; the twenty that remained are regrouped by
topic and eight more added for changes no entry covered. Three of those
eight matter to someone upgrading. Five root modules and four re-exports
left the public library surface and Node::connections narrowed, none of it
recorded anywhere; the entry names what to use instead and distinguishes
the removed connection-phase enum from the Noise type of the same name,
which is a different type that still exists. Tracing targets moved, so an
existing RUST_LOG filter stops matching rather than erroring. And the
handshake resend interval key no longer governs the first resend, which is
now a constant, though it still governs later ones.

Seven more entries cover the work that landed after the first content pass
was written: the experimental native datagram API, the fipsctl probe
diagnostic, per-instance transport addressing, the app-owned UDP socket
seam, and the connect, disconnect and path-MTU fixes. The four bug fixes
among them all reach the deployed line, so the release notes no longer
claim this release carries exactly one fix for a shipped bug; it carries
four.

There is no security section, because after the split every security entry
belongs to the point release. The release notes say so plainly rather than
leaving a reader upgrading across both releases to conclude this one
carries no security work.

The notes are organized by audience, since the release spans OpenWrt
routers, embedders, FreeBSD, and the existing platforms, and a single list
serves none of them. The native datagram API is given a section of its own
rather than folded into the embedding seam: it is a client-facing API
rather than a way to host a node, and its one rule with no Berkeley-socket
counterpart, that the v1 wire carries no half-close, needs to be somewhere
a client author will read it. FreeBSD is advertised as supported on x86_64
only, stated wherever the platform appears. Android is advertised as an
embedding seam and not as a supported platform: a compile-gated library
surface with no artifact and no host application guide.

The configuration table rename is carried through every shipped file that
taught the old spelling: nine documentation files, the OpenWrt sample
config and a test generator, twenty-two sites in all. Guides written this
same cycle were among them, which is how the omission was found. The
documentation that arrived with the native API was checked for the same
omission and was already clean. The compatibility tests keep the old
spelling deliberately, since they exist to test the fold.

The changelog section is the fold of master's [Unreleased], not a snapshot
of it. An earlier version of this commit took a copy that then drifted, so
each section ended up holding a bullet the other did not and re-folding
them would have picked a winner silently. Both causes were fixed on master
instead — the NixOS module had never been recorded there, and the
pre-release batch of fixes was new — so [Unreleased] is a strict superset
and this is a copy rather than a merge. [0.5.0] carries all forty-six
bullets byte for byte, [Unreleased] is empty, and [0.4.2] is untouched,
checked by hashing it against master's copy.

The BLE work landed after the content pass and gets one summary entry in
the changelog and one section in the release notes rather than nine
bullets: the ble_available gate replacing target_os = "linux",
packet-boundary recovery for stream-oriented backends, peer recognition by
node identity instead of a rotating link address, the L2CAP PSM moving
into the backend seam and onto the advertisement, the embedder-supplied
Android radio, bounded probe retry, and inbound handshakes moved off the
accept loop.

The two release-notes copies no longer share their link paths. Relative
links resolve from one directory only, so the seven written for
docs/releases/ all 404ed from the root copy. The root copy now uses paths
from the repository root and the versioned copy keeps the ../ form; both
sets were resolved against the tree. The same two links are broken the
same way in the v0.4.0 through v0.4.2 notes, left as shipped history.

The contributor tallies are re-derived against maint..HEAD rather than
adjusted: twenty commits from outside the project and 171 from me, with
Arjen at fifteen and fr34aky at two. An earlier count of twelve and 138
was carried from a measurement taken three days before this content was
written, and the BLE branch widened the gap after it. Arjen's NixOS flake
module, the UDP sin6_scope_id fix and most of the BLE rework were
uncredited, as was fr34aky's L2CAP PSM seam. They want one last re-derive
at tag time if anything lands before the tag.

A sweep of all 99 tracked markdown files against the tree corrected
fifty-three of them. Four told the reader to run a build.sh that does not
exist; the only harness builder is testing/scripts/build.sh. The BLE build
prerequisites were described as optional on the strength of a probe that
build.rs does not perform, and bluez was named a build prerequisite when
libdbus-sys asks only for libdbus-1-dev and pkg-config and bluez is the
runtime daemon. Link cost is the primary sort key in next-hop ranking, not
reserved for future use; Ethernet runs on macOS as well as Linux; the BLE
MTU is the L2CAP CoC MTU rather than a negotiated ATT_MTU; effective
Ethernet MTU is 1497; the LAN discovery subsystem is src/mdns and eight
citations still named a src/discovery that never existed here. The
connectivity states in three tutorials were invented, and their jq filters
matched nothing including healthy peers. One command filtered on a literal
fd97: address prefix, which only the first byte of fixes, so it returned
empty for all but one reader in 256 and every later step using the
variable failed silently. transports.tor.advertise_on_nostr was
undocumented despite being validated against node.rendezvous.nostr.enabled.

The transport design document gains the BLE section it never had, written
from the source: the backend cascade and its compile_error tripwire, the
platform gate, the PSM advertisement wire layout and the byte budget that
forces a 16-bit service-data key, and the probe and admission bounds.

Three source files carried the same class of staleness and are corrected
with the documentation: the OpenWrt ipk usage line and Makefile error text
both named a packaging/openwrt that does not exist, and chaos.sh parsed
--subnet without listing it.

Folded in with the content commit, having been prepared alongside it:

The three GitHub Action pins that had gone stale. Every third-party
action is pinned to a commit SHA, nothing reports that a pin has aged,
and re-resolving all ten against their tags found dorny/test-reporter@v2,
taiki-e/install-action@v2 and vmactions/freebsd-vm@v1 had moved. The
three install-action@nextest references stay unpinned, since that action
reads the tool to install from the ref name. check-action-pins.sh passes
at 75 references and all nine workflow files parse.

The lockfile refresh, which is the mutating half of the dependency sweep.
Thirty-six packages move to their latest semver-compatible versions and
every one is transitive; nothing declared in Cargo.toml changes version.
No advisory forces any of them. It was taken before the validation
battery, because a gate run against a lockfile that later moves proves
nothing about what ships.

The sha2 0.10 to 0.11, hkdf 0.12 to 0.13 and bech32 0.11 to 0.12 majors,
three of the four deferred at v0.4.0 for change surface rather than
security. All three land with no source change. sha2 and hkdf must move
together, since both depend on digest 0.11, and neither changes an
algorithm. That matters because the chaining-key KDF in the Noise
handshake is built on Hkdf::<Sha256>, where an output change would be a
wire break rather than a compile error; no known-answer vectors exist for
that path, so the wire-compatibility gate is what covers it. secp256k1
0.31 is deliberately absent, since nostr's own requirement would leave
two copies of the ECC library in the tree.

The README support matrix, rebuilt as one feature table broken out by
Linux variety. A single Linux column hid that Debian, Ubuntu, Arch and
NixOS are one glibc build differing in packaging, that OpenWrt is musl
and drops BLE, and that Android is not a daemon platform. Transport rows
sort by how many platforms carry them. A Native API row reads its
platform set from the cfg gates. The installer row becomes a package
format row naming the artifact, and only the .deb is exercised per
release.

Four changelog and release-note gaps the BLE re-walk found: a Bluetooth
LE bullet stranded inside the released 0.4.2 section, a missing Fixed
entry for the scan and probe loop counting a pool-refused connection as
an established link, the unnamed embedder call that installs an
application-owned radio, and the fact that stopping the transport now
stops scanning as well as advertising.

Three release-document gaps found walking the unsurveyed commits: the UDP
reuse-flag fix stated in the direction opposite to the one it was made,
with the silent second-daemon bind it prevents left unsaid; the corrected
native-API socket paragraph carried into both release-note copies, which
still named SOCK_SEQPACKET on FreeBSD and two kernels where three are
handled; and the coordinate-cache hardening, which shipped with no text
anywhere despite adding four operator-visible status fields. That last
entry states plainly that the checks are mitigations and not a closure,
since the coordinate is still not authenticated.

Also folded in, the documentation pass that followed the content commit:

A stage-pipeline diagram for the probe, embedded in the fipsctl
reference under the five-stage list. It draws the five stages left to
right with each stage's failure reasons below it, and the bypass that
skips both lookup stages when the coordinates are cached or the target
is a direct peer. Its branches come from the probe state machine rather
than from the report, so the path stage is drawn as the one failure that
does not stop the probe.

A rewrite of the README's "What FIPS does" section. It now opens with
what a machine running FIPS gets, rather than with the two deployment
modes, and gives the self-organizing and permissionless property its own
paragraph since it holds for both modes.

A regrouping of the README's feature list into the mesh, getting traffic
onto it, and running a node, with a bullet added for the native datagram
API, which had none despite sitting in the support matrix. The Quick
start now leads with the released packages rather than a source build.
It also fixes a real defect: the package enables fips.service and
fips-dns.service and starts neither on a fresh install, so .fips name
resolution was silently dead until the next reboot and neither page said
to start the service.

A rewrite of the release notes. They opened with seven subsections of
upgrade caveats and reached the first feature two hundred lines in; they
now open with a summary of the release and elaborate below it in the
same order. Android is stated as supported through an embedded crate
rather than as a standalone daemon, consistently across all three
documents. The OpenWrt pair is corrected: it is 802.11s between routers
with FIPS supplying encryption, authentication and routing, plus a
convention of an open !FIPS SSID a client joins over WiFi, not meshing
over a router's own radios. The probe's path output is described as the
least-common-ancestor walk, which is the worst-case fallback route
rather than the route a packet takes. Detail that did not change what a
reader does was cut from the notes and kept in the changelog.
2026-08-30 10:42:59 +00:00

14 KiB

Enable Nostr-Mediated Discovery and NAT Traversal

Nostr-mediated discovery lets FIPS nodes find each other (and punch through UDP NAT) using public Nostr relays as the signaling channel. The feature ships in every stock packaging artifact but is off by default — it activates when an operator sets node.rendezvous.nostr.enabled: true. Default relay and STUN-server lists ship in the config; both are optional overrides. See ../design/fips-nostr-discovery.md for the design and rationale; see ../reference/configuration.md for the full knob inventory.

The table was called node.discovery before v0.5.0; that spelling still parses and logs one deprecation warning naming the move, so an existing config keeps working (see ../reference/configuration.md).

Nostr discovery provides three independent capabilities. They can be enabled separately; most deployments end up using two or three of them together.

  1. Resolve a known peer's address by npub. Your daemon consumes adverts from the relays to look up the current network endpoint for a peer you have configured by npub. You don't have to know their IP / port / transport in advance.
  2. Publish your own endpoint so others can resolve you. Your daemon publishes a signed advert listing the transports it will accept connections on. Has two sub-shapes depending on your network topology: UDP (using NAT traversal if needed) or TCP. Running a Tor onion service is a separate deployment mode, covered in its own section below.
  3. Discover peers without prior configuration. Your daemon subscribes to all adverts on a chosen application namespace and treats any publisher as a connection candidate. The most permissive posture; useful for ambient mesh participation.

Each capability is covered below as one or more scenarios with the minimal YAML fragment that enables it. Only keys relevant to Nostr discovery are shown; surrounding node, transport, TUN, DNS, and peer configuration follows the usual shape.

All scenarios assume node.identity is set to a persistent key — an ephemeral identity would invalidate any advert the moment the node restarts. See persistent-identity.md for the persistent-key setup.

For hand-held walkthroughs of each capability, see the resolve-peers-via-nostr, advertise-your-node, and open-discovery tutorials.

Capability 1: Resolve a known peer's address by npub

The node does not publish any advert of its own. It only consumes adverts for peers it has explicitly listed with via_nostr: true. This is the right shape for a client that wants Nostr-mediated resolution without becoming a rendezvous target itself.

node:
  identity:
    persistent: true
  rendezvous:
    nostr:
      enabled: true
      advertise: false
      policy: configured_only

transports:
  udp:
    bind_addr: "0.0.0.0:2121"

peers:
  - npub: "npub1peer..."
    alias: "remote-node"
    via_nostr: true
    connect_policy: auto_connect

What this achieves: dial endpoints for this peer are taken from the peer's published Nostr advert. configured_only is the default — it is shown here for clarity.

Note: You can also supply a static address alongside via_nostr: true (for example, while testing, or as a known-good fallback if the advert is stale). Add an addresses block to the peer entry; static addresses are tried first on dial and Nostr-resolved endpoints are appended as additional candidates.

Capability 2: Publish your own endpoint so others can resolve you

This capability has three sub-scenarios depending on the network shape your node sits behind.

Sub-scenario 2a: UDP (using NAT traversal if needed)

The node has a public IP (or a stable port-forward) and binds UDP on a known port. It publishes udp:host:port to the advert relays. Any peer that knows this node's npub and has Nostr discovery enabled can dial it without knowing the address out-of-band.

When UDP is wildcard-bound (0.0.0.0:2121, the default), the daemon needs help knowing what IP to put in the advert. There are two ways: STUN auto-discovery (public: true) or an explicit override (external_addr). Both are first-class options; pick the one that fits the deployment.

node:
  identity:
    persistent: true
  rendezvous:
    nostr:
      enabled: true
      advertise: true

transports:
  udp:
    bind_addr: "0.0.0.0:2121"
    advertise_on_nostr: true
    public: true                  # ← STUN auto-discovery

Or, when the public IP is known up front (static residential IP, cloud Elastic IP behind 1:1 NAT, etc.):

transports:
  udp:
    bind_addr: "0.0.0.0:2121"
    advertise_on_nostr: true
    public: true                         # ← required, master switch
    external_addr: "203.0.113.45:2121"   # ← explicit address

external_addr accepts a bare IP (combined with the bind port) or a full host:port. public: true is the master switch that gates UDP advertisement; inside that branch, the daemon picks the advertised address in precedence order: explicit external_addr (no STUN observation), a non-wildcard bind_addr, or STUN auto-discovery. Setting external_addr alongside public: true skips STUN entirely — there is no logging cross-check. If UDP is bound directly to a public IP rather than to a wildcard, neither external_addr nor STUN is needed — but advertise_on_nostr: true and public: true are still both required for the daemon to publish the endpoint.

What this achieves: the node publishes a single udp:<public-ip>:2121 endpoint to the three default advert relays (wss://relay.damus.io, wss://nos.lol, wss://offchain.pub).

What the other side needs: either a static addresses entry for this peer, or a peer entry with via_nostr: true and an empty (or omitted) addresses list — the advert-resolved endpoint will be used at dial time. Static and Nostr-resolved addresses can also be combined: when both are present, static addresses are tried first and Nostr-resolved endpoints are appended as fallback.

When the node is behind NAT

If this node doesn't have a stable public UDP endpoint, advertise udp:nat. The daemon runs the STUN + offer/answer exchange with the peer and punches through the NAT to establish a direct UDP link. The peer can either have a public endpoint of its own or also be behind NAT — both shapes work, as long as at least one side has a NAT type compatible with hole-punching.

node:
  identity:
    persistent: true
  rendezvous:
    nostr:
      enabled: true
      advertise: true
      dm_relays:                       # overrides the default three-relay
        - "wss://relay.damus.io"        # set with two for demonstration;
        - "wss://nos.lol"               # omit this block to keep the defaults
      stun_servers:
        - "stun:stun.l.google.com:19302"
        - "stun:stun.cloudflare.com:3478"

transports:
  udp:
    bind_addr: "0.0.0.0:2121"
    advertise_on_nostr: true
    public: false

peers:
  - npub: "npub1peer..."
    alias: "nat-peer"
    addresses:
      - transport: udp
        addr: "nat"
    via_nostr: true
    connect_policy: auto_connect

What this achieves: the node publishes a udp:nat endpoint plus its signaling relays in the advert. When either side initiates, an encrypted offer is sealed to the peer's npub, a matching answer comes back, and both sides punch at the negotiated time. On success, the punch socket is adopted as an FMP UDP transport and Noise IK proceeds normally.

Validation: advertise_on_nostr: true with public: false on UDP requires dm_relays and stun_servers to be non-empty. Both ship with non-empty defaults (three relays and three STUN servers respectively), so the default config passes. The node fails startup only if the operator has explicitly emptied either list — a udp:nat advert without signaling relays or STUN servers is unreachable by construction.

Hole-punching is best-effort. It works reliably when both sides are full-cone or port-restricted NATs. Symmetric NAT on either side typically defeats the punch — the public port a peer sees varies per remote endpoint, so the address learned via STUN does not match the mapping the peer actually needs. The punch attempt times out after punch_duration_ms. udp:nat is the only NAT-traversal mechanism in FIPS; when it can't succeed, there's no in-protocol substitute. Being reachable then becomes a deployment-prerequisite question rather than a transport question — a publicly reachable port (UDP or TCP — both require the same kind of network resource) published as a direct advert per Sub-scenario 2a or 2b.

Sub-scenario 2b: TCP

The node has a public IP (or a stable port-forward) and accepts inbound TCP. It publishes tcp:host:port to the advert relays.

TCP endpoints exist to serve peers whose networks filter outbound UDP (corporate LANs, restrictive guest WiFi). NAT traversal does not apply: the publishing node is publicly reachable on TCP, and the dialing peer's network only needs to permit outbound TCP to the advertised port.

node:
  identity:
    persistent: true
  rendezvous:
    nostr:
      enabled: true
      advertise: true

transports:
  tcp:
    bind_addr: "0.0.0.0:8443"
    advertise_on_nostr: true
    external_addr: "203.0.113.45:8443"

external_addr is typically required on cloud setups (AWS Elastic IP, etc.) where binding directly to the public IP returns EADDRNOTAVAIL. When TCP is bound directly to a public IP, the override is unnecessary.

What this achieves: the node publishes a tcp:<public-ip>:8443 endpoint to the advert relays. Peers with Nostr discovery enabled dial by npub without out-of-band address exchange.

Tor onion node

A separate deployment mode for nodes that want anonymity and censorship-resistance properties on the data plane. Functionally this still uses Capability 2 (publishing an endpoint to advert relays) — the difference is that the published endpoint is a Tor hidden service rather than a public IP.

The node runs a Tor onion service in directory mode (Tor-managed HiddenServiceDir) and advertises the .onion address. Peers dial via their local Tor SOCKS5 proxy without ever knowing the onion string out-of-band. For the Tor daemon side of this setup, including the inbound-mode trade-offs and the torrc directives each requires, see deploy-tor-onion.md.

node:
  identity:
    persistent: true
  rendezvous:
    nostr:
      enabled: true
      advertise: true

transports:
  tor:
    mode: directory
    socks5_addr: "127.0.0.1:9050"
    advertised_port: 8443
    directory_service:
      hostname_file: "/var/lib/tor/fips/hostname"
      bind_addr: "127.0.0.1:8444"
    advertise_on_nostr: true

What this achieves: the node publishes a tor:<hash>.onion:8443 endpoint alongside any other advertised transports. The advert itself is still published over clearnet WebSocket relays — Tor protects the data plane, not the discovery plane. See the security and threat model section in ../design/fips-nostr-discovery.md for the trade-off and how to route relay traffic through Tor as well.

Capability 3: Discover peers without prior configuration

Under policy: open, any node that publishes an advert under the same app namespace becomes a candidate. Discovered peers are queued for connection attempts subject to open_discovery_max_pending.

node:
  identity:
    persistent: true
  rendezvous:
    nostr:
      enabled: true
      advertise: true
      policy: open
      open_discovery_max_pending: 64
      app: "my-experiment.v1"

transports:
  udp:
    bind_addr: "0.0.0.0:2121"
    advertise_on_nostr: true
    public: true

peers: []

What this achieves: peers are discovered entirely through ambient advert traffic on the configured relays. Setting a non-default app value (replacing fips-overlay-v1) scopes the discovery set to participants who opt into the same experiment and avoids being joined to unrelated overlays that happen to share the default namespace.

Scope warning: Open discovery is an admission-free mode. Any node that publishes on the same app name and passes the peer-ACL check becomes a connection candidate. If you rely on peer ACLs for admission control, verify that list is set correctly before enabling this mode. See ../reference/security.md for the peer ACL format.

See also