laantungir/fips
1
0
Fork 0
mirror of https://github.com/jmcorgan/fips.git synced 2026-07-30 19:46:15 +00:00
Code Issues Packages Projects Releases Wiki Activity

docs: refresh tutorials, how-to, design, reference, and examples for v0.4.0

Browse Source 
Pre-cut documentation pass for the 0.4.0 release, verified against current source.

Corrections:
- fipsctl: stale 'show identities'/'show node' -> 'show status'
  (host-a-service, run-as-unprivileged-user)
- mesh address derivation: first 16 bytes of SHA-256(pubkey) with the leading
  byte set to 0xfd, not a fixed fd97: prefix (reach-mesh-services,
  ipv6-adapter-walkthrough)
- gateway control socket mode 0660 -> 0770 (troubleshoot-gateway)
- Tor example: add advertised_port: 8443 so the published port matches the
  prose (enable-nostr-discovery)
- bloom mesh-size estimate rewritten to the OR-union-of-peer-filters algorithm;
  plus mtu deep-link, gateway pool wording, and a NAT failure-mode line
- examples: delete orphaned nostr-rs-relay config, accept inbound to the local
  8443 TCP listener, fix fd::/8 -> fd00::/8 typos, dotless wireguard alias

Additions:
- new Nym mixnet transport section (fips-transport-layer) and the architecture
  transport list
- new LAN/mDNS discovery section (fips-nostr-discovery)
- reference docs: Nym transport, LAN discovery, and new control/stats surfaces;
  drop ble from the connect transport list
This commit is contained in:
Johnathan Corgan
2026-06-14 15:14:05 +00:00
parent 3e0d9f5726
commit 507086e39d
22 changed files with 436 additions and 86 deletions
Download Patch File Download Diff File Expand all files Collapse all files
docs/design/fips-architecture.md
+5 -3
View File
@@ -221,9 +221,11 @@ discovery protocol, and error-recovery integration view live in
## Transport Abstraction
FIPS treats the communication medium as a pluggable component. UDP,
TCP, raw Ethernet, Tor, and BLE all implement the same small datagram
interface (send, receive, report MTU) and feed peers into a single FMP
routing layer; radio and serial transports are in the planned set.
TCP, raw Ethernet, Tor, BLE, and Nym all implement the same small
datagram interface (send, receive, report MTU) and feed peers into a
single FMP routing layer; radio and serial transports are in the
planned set. Nym (an outbound-only mixnet transport) and Tor are
privacy-oriented deployment modes rather than failover paths.
Multi-transport nodes bridge between networks transparently. The
transport-layer specification — including per-transport categories,
the trait surface, the connection model, and implementation status —
docs/design/fips-bloom-filters.md
+18 -8
View File
@@ -180,7 +180,7 @@ network with no overlap (excluding the node itself at the split point).
All peers — including non-tree mesh shortcuts — still **receive**
FilterAnnounce messages and **store** received filters locally. These
stored filters are consulted during routing (step 3 of `find_next_hop()`)
stored filters are consulted during routing (step 4 of `find_next_hop()`)
for single-hop shortcut discovery. However, mesh peer filters contain
only the mesh peer's own tree-propagated information, not transitive
entries from the broader network.
@@ -339,14 +339,24 @@ positions that folding produces.
## Mesh Size Estimation
Each filter's saturation can be inverted into an estimated entry count
A filter's saturation can be inverted into an estimated entry count
via the standard formula `n ≈ -(m/k) · ln(1 − X/m)`, where `m` is the
filter size in bits, `k` is the hash count, and `X` is the population
count. Combining the parent's inbound filter with the children's
inbound filters gives an estimate of the whole network: parent + each
child's subtree are disjoint by construction, and adding 1 for the
node itself yields the total. The result is cached on the node and
exposed through the control socket and `fipstop` dashboard.
count. Rather than estimate per-filter and sum, the node first builds
an **OR-union of every connected peer's inbound filter** — all routing
peers, including cross-links, not just the tree parent and children —
inserts its own address into the union, and inverts the cardinality
**once on the resulting union**. Because filter propagation is
split-horizon (each outgoing filter excludes the peer it routes back
to), every routing peer advertises a near-complete "whole mesh minus
my subtree" view, so the union covers the network. OR-ing is
idempotent, so overlapping bits deduplicate instead of over-counting,
and folding in all peers rather than only the tree neighborhood damps
the count flap on a parent switch (the cross-links still carry the
upward coverage) and removes any dependence on tree-declaration cache
freshness. The result is cached on the node and exposed through the
control socket and `fipstop` dashboard. (See `compute_mesh_size()` in
`src/node/mod.rs`.)
The estimator refuses to produce a value when any contributing filter
is above the antipoison FPR cap (`node.bloom.max_inbound_fpr`,
@@ -378,7 +388,7 @@ as described above.
| 500ms rate limiting | **Implemented** |
| FilterAnnounce gossip (all peers) | **Implemented** |
| Filter cardinality logging | **Implemented** |
| Mesh size estimation (parent + children + 1) | **Implemented** |
| Mesh size estimation (OR-union of peer filters) | **Implemented** |
| Inbound FPR cap (antipoison) | **Implemented** |
| Size class negotiation | Future direction |
| Folding support | Future direction |
docs/design/fips-gateway.md
+1 -1
View File
@@ -218,7 +218,7 @@ involving the DNS proxy or the pool.
### Virtual IP Pool
The pool allocates IPv6 addresses from a configured CIDR (default
The pool allocates IPv6 addresses from a required CIDR (commonly
`fd01::/112`). Each address maps to one mesh destination, keyed by
`NodeAddr` rather than by hostname — different `.fips` aliases for
the same node share a virtual IP. Address 0 (the network-equivalent)
docs/design/fips-mtu.md
+1 -1
View File
@@ -251,7 +251,7 @@ would later drop.
The adapter integrates with the MTU subsystem rather than owning it.
The "why we clamp and what `max_mss` means" lives here in the MTU
design; the "how the clamp is implemented at the TUN" lives in the
[IPv6 adapter](fips-ipv6-adapter.md#tcp-mss-clamping) doc.
[IPv6 adapter](fips-ipv6-adapter.md#tun-side-tcp-mss-clamping) doc.
## ICMP Packet Too Big
docs/design/fips-nostr-discovery.md
+186 -1
View File
@@ -1,4 +1,13 @@
# FIPS Nostr-Mediated Discovery and NAT Traversal
# FIPS Discovery: Nostr-Mediated and LAN/mDNS
FIPS nodes have two discovery mechanisms beyond the static `peers[]`
list. The bulk of this document describes **Nostr-mediated discovery**,
which works across the internet using public Nostr relays as a
signaling channel and can punch through UDP NAT. A second, much
simpler mechanism — **LAN/mDNS discovery** — finds peers on the same
local link with no relay, STUN, or NAT traversal at all; it is
described in its own section near the end. The two are independent: a
node can enable either, both, or neither.
Nostr-mediated discovery lets FIPS nodes find each other, and if
necessary, punch through UDP NAT, using public Nostr relays as the
@@ -377,6 +386,182 @@ semaphore and replay-cache layers downstream.
advert says "I am npub X at 1.2.3.4:5678" but whose FMP handshake
presents a different static key is rejected at the mesh layer.
## LAN/mDNS discovery
LAN discovery is a separate, link-local discovery mechanism that finds
peers on the same broadcast domain using mDNS / DNS-SD
([RFC 6762](https://www.rfc-editor.org/rfc/rfc6762) /
[RFC 6763](https://www.rfc-editor.org/rfc/rfc6763)). Unlike
Nostr-mediated discovery, it contacts no relay, runs no STUN
observation, and performs no NAT traversal: an endpoint learned from a
LAN advert is by construction routable from the consumer's own link.
The result is sub-second peer pairing on the same LAN.
It is unrelated to the "LAN candidate" terminology used in the
NAT-traversal sections above (which refers to a host's own
locally-bound address offered as a hole-punch candidate). LAN/mDNS
discovery is a distinct subsystem under `src/discovery/lan/`.
### Role
LAN discovery adds two capabilities, both confined to the local link:
- **Advertising.** The node publishes a `_fips._udp.local.` DNS-SD
service advert carrying its `npub`, its protocol version, and (if
configured) a discovery scope. The advert is multicast on the local
link only; it does not leave the broadcast domain unless the
operator's network bridges mDNS.
- **Browsing.** The node concurrently browses for the same service
type, learns the endpoints of other FIPS nodes on the link, and
initiates a normal FMP link to each newly-seen peer.
The mDNS service type is `_fips._udp.local.`
(`src/discovery/lan/mod.rs:45`). Per RFC 6763 the `_udp` label denotes
the IP transport used for the advert, not the FIPS upper protocol —
both UDP and TCP FIPS endpoints announce under the same service type
because the link-layer handshake travels over UDP either way. (In
practice LAN discovery dials only over a UDP transport; see the
handshake subsection.)
### When to use it
- **You run several FIPS nodes on one LAN** (a lab bench, an office
segment, a home network) and want them to find each other without
hand-maintaining `peers[]` blocks or standing up Nostr discovery.
- **You want the lowest-latency pairing path.** Same-link pairing
completes in well under a second with no relay round-trip.
Skip it when nodes are not on a shared broadcast domain (mDNS does not
cross routed boundaries), or when you do not want the node to multicast
its identity on the local link. LAN discovery is **opt-in and disabled
by default**, so doing nothing leaves it off.
### How it works
The LAN discovery runtime (`src/discovery/lan/mod.rs`) is started
during node initialization when `node.discovery.lan.enabled` is true.
It is independent of Nostr discovery and runs even when Nostr is
disabled (`src/node/lifecycle.rs:1159-1162`). Startup requires an
operational UDP transport: the node advertises the port of its
lowest-`TransportId` operational, non-bootstrap UDP transport, chosen
deterministically so the advertised port is stable across restarts
(`src/node/lifecycle.rs:1169-1180`). If no such port exists, the
runtime returns `NoAdvertisedPort` and LAN discovery does not start
(`src/discovery/lan/mod.rs:156-158`).
The runtime does two things concurrently:
1. **Responder.** It registers a DNS-SD service with instance name
`fips-<first-16-chars-of-npub>` and a TXT record carrying the keys
below. `mdns-sd`'s address auto-detection appends every non-loopback
interface address, with `127.0.0.1` seeded so same-host peers and
integration tests can still resolve the advert
(`src/discovery/lan/mod.rs:182-203`).
2. **Browser.** A background pump receives `ServiceResolved` events for
the same service type. For each resolved advert it extracts the
`npub` and `scope` TXT values, drops adverts that echo the node's own
npub, drops cross-scope adverts (see scope filtering), drops records
without an `npub`, and surfaces one `LanDiscoveredPeer` per routable
interface address (`src/discovery/lan/mod.rs:212-299`). IPv6
unicast link-local addresses without an interface scope id are
skipped, since they cannot be dialed unambiguously
(`src/discovery/lan/mod.rs:348-365`).
The TXT record carries three keys (`src/discovery/lan/mod.rs:47-55`):
| TXT key | Contents |
| --- | --- |
| `npub` | bech32-encoded npub of the advertising node |
| `scope` | the node's discovery scope, if one is configured (omitted otherwise) |
| `v` | FIPS protocol version (the same `PROTOCOL_VERSION` used by the Nostr advert) |
Once per node tick, the node drains browser events and acts on them in
`poll_lan_discovery()` (`src/node/lifecycle.rs:907`, called from
`src/node/handlers/rx_loop.rs:266`). For each discovered peer it finds
a UDP transport whose family matches the peer address, parses the
`npub` into a `PeerIdentity`, skips peers it is already connected to or
currently connecting to, and otherwise initiates a connection.
### Handshake: Noise IK
LAN-discovered peers are dialed through the standard FMP outbound link
path. `poll_lan_discovery()` calls `initiate_connection()`
(`src/node/lifecycle.rs:380`), which, for connectionless transports
such as UDP, allocates a link and **starts the Noise IK handshake**
(documented at `src/node/lifecycle.rs:373-374`). This is the same
link-layer handshake used by every other FMP connection — IK at the
link layer per the FIPS architecture — not a different pattern for LAN
peers.
The mDNS advert is **unauthenticated**: anyone on the link can
multicast a TXT claiming any `npub`. Identity is proven end-to-end by
the Noise IK handshake against the observed endpoint. A spoofed advert
carrying another node's npub fails the handshake — the impostor does
not hold the matching static key — and the half-open link is dropped.
The mDNS advert is therefore a routing hint, never an identity
assertion, exactly as a Nostr advert is treated (a successful contact
is not trusted until FMP's Noise IK handshake completes).
> Note: a stale source doc-comment at `src/node/lifecycle.rs:904-906`
> describes this path as a "Noise XX" handshake. That comment is
> inaccurate — the path uses Noise IK as described above. The comment
> is flagged for a separate source fix and does not reflect actual
> behavior.
### Scope filtering
When a discovery scope is configured, the advert carries it in the
`scope` TXT entry and the browser surfaces only peers whose advert
carries a matching scope. Nodes on the same physical LAN but configured
for different mesh networks therefore do not cross-feed each other.
The scope is resolved by `lan_discovery_scope()`
(`src/node/lifecycle.rs:880-902`): the explicit
`node.discovery.lan.scope`, if non-empty, is used directly. Otherwise
the node falls back to deriving a scope from the Nostr discovery `app`
tag (stripping the `fips-overlay-v1:` prefix when present). This lets
an application keep its public, relay-visible Nostr `app` tag generic
while still isolating LAN discovery per private network, or share one
value across both. A node with no scope on either side surfaces all
adverts it sees on the link.
### Configuration
LAN discovery is configured under `node.discovery.lan.*`
(`src/config/node.rs:222-227`, `src/discovery/lan/mod.rs:88-129`):
| Key | Type | Default | Meaning |
| --- | --- | --- | --- |
| `node.discovery.lan.enabled` | bool | `false` | Master switch. LAN discovery is opt-in; default-off avoids an unexpected per-link identity multicast on upgrade. |
| `node.discovery.lan.service_type` | string | `_fips._udp.local.` | DNS-SD service type. Overridable mainly so integration tests can isolate multiple services on one loopback interface. |
| `node.discovery.lan.scope` | string (optional) | unset | Application/network scope carried in the LAN-only `scope` TXT record. Kept deliberately separate from the public Nostr `app` tag. When unset, the scope falls back to the derived Nostr `app` value. |
The identity surface published over mDNS (`npub`, version, optional
scope) is a strict subset of what `nostr.advertise` already publishes
publicly, so enabling LAN discovery adds no marginal privacy cost
beyond making the node's presence observable on its own local link.
### Relationship to Nostr discovery
The two mechanisms are complementary and independent:
| | Nostr-mediated | LAN/mDNS |
| --- | --- | --- |
| Reach | Internet-wide, via relays | Same broadcast domain only |
| Signaling channel | Public Nostr relays | mDNS multicast on the local link |
| NAT traversal | STUN + UDP hole-punch for `udp:nat` peers | None — endpoint is link-routable by construction |
| Identity carrier | signed kind 37195 advert (authenticated at publish) | unauthenticated mDNS TXT (routing hint only) |
| Identity proof | FMP Noise IK on the connection | FMP Noise IK on the connection |
| Default | disabled (`nostr.enabled: false`) | disabled (`lan.enabled: false`) |
| Scope key | `app` tag (public) | `scope` TXT (link-local), falls back to `app` |
Both ultimately converge on the same trust boundary: discovery only
supplies candidate endpoints, and no peer is trusted until FMP's Noise
IK handshake confirms the claimed identity. A node may run both at
once — for example, advertising globally over Nostr while also pairing
instantly with same-LAN peers — with no interaction between the two
beyond the shared scope fallback.
## See also
- [../how-to/enable-nostr-discovery.md](../how-to/enable-nostr-discovery.md)
docs/design/fips-transport-layer.md
+120 -1
View File
@@ -120,6 +120,7 @@ for internet connectivity:
| UDP/IP | host:port | 1280–1472 | Unreliable | Primary internet transport |
| TCP/IP | host:port | Stream | Reliable | Requires length-prefix framing |
| Tor | .onion | Stream | Reliable | High latency, strong anonymity |
| Nym | host:port | Stream | Reliable | Mixnet, outbound-only, strong anonymity |
**Shared medium transports** operate over broadcast- or multicast-capable
media:
@@ -190,6 +191,7 @@ proceed.
| --------- | ---------------- |
| TCP/IP | TCP three-way handshake |
| Tor | Circuit establishment (typically 10–60s, default timeout 120s) |
| Nym | SOCKS5 connect through mixnet (minutes possible, default timeout 300s) |
| BLE | L2CAP CoC or GATT connection |
| Serial | Physical connection (static) |
@@ -599,6 +601,120 @@ SOCKS5-level errors, MTU rejections, accepted/rejected inbound
connections, and Tor control-port errors. The full counter table
lives in [../reference/transports.md](../reference/transports.md).
## Nym: The Mixnet Transport
The Nym transport routes FIPS traffic through the Nym mixnet, providing
network-level anonymity via Sphinx packet routing and timing
obfuscation. It uses the "mixnet-as-proxy" pattern: a node connects
outbound through a local `nym-socks5-client` SOCKS5 proxy, which carries
the traffic into the mixnet. The `nym-socks5-client` runs as a separate
process alongside the fips daemon and must be started independently.
Like Tor, Nym is a privacy-oriented deployment mode chosen for the
anonymity properties of the mixnet, not a failover for other transports.
Like TCP and Tor, it is connection-oriented and reliable; the same
TCP-over-TCP considerations apply, and cost-based parent selection
naturally deprioritizes the high-latency Nym links.
### Architecture
The Nym transport is a separate `NymTransport` implementation. It reuses
the FMP header-based stream reader (`tcp/stream.rs`) for packet framing
on the underlying byte stream, and follows the same connection-pool
pattern as the TCP and Tor transports.
It maintains two pools: a `ConnectingPool` for background SOCKS5
connection attempts, and an established pool of `NymConnection` entries.
Each `NymConnection` holds a write half, a per-connection receive task,
the configured MTU, and a connection timestamp.
| Property | Value |
| -------- | ----- |
| Addressing | IP:port or hostname:port |
| Default MTU | 1400 bytes |
| Framing | FMP header-based (shared with TCP) |
| Connection model | Outbound-only, non-blocking connect through SOCKS5 |
| Platform | Cross-platform (requires external nym-socks5-client) |
### Outbound-Only
The Nym transport is strictly outbound. It supports no inbound service:
`accept_connections()` returns `false` and `discover()` returns no
peers. A node using the Nym transport can initiate links to remote peers
through the mixnet, but cannot accept inbound connections over Nym. (A
node can still accept inbound links over other transports it runs.)
### Address Types
The Nym transport accepts two address formats, parsed into an internal
target address:
- **IP:port** — a numeric IP and port, sent to the SOCKS5 proxy as a
numeric target.
- **Hostname:port** — the hostname is passed through SOCKS5 so it is
resolved on the exit side rather than locally.
Both forms are routed through the same SOCKS5 proxy.
### Connection Establishment
Connection setup follows the same non-blocking pattern as the TCP and
Tor transports. When FMP needs to reach a peer, the node initiates a
background connect (`connect_async`). The transport spawns a background
tokio task that opens a SOCKS5 connection through the local
`nym-socks5-client`, configures the socket (including TCP keepalive),
splits the stream, and spawns a per-connection receive loop using the
shared FMP stream reader. The call returns immediately while the connect
proceeds in the background.
SOCKS5 connection setup through the mixnet can take much longer than a
direct TCP connection because each connection traverses multiple mix
nodes with timing obfuscation. Accordingly the connect timeout defaults
to 300 seconds (`connect_timeout_ms`). Non-blocking connect is essential
here — a blocking connect would stall the FMP event loop for the
duration of mixnet setup. As a fallback, `send_async(addr, data)`
performs a connect-on-send if no connection to the address yet exists.
Each outbound packet is checked against the configured MTU before being
written; an oversized packet is rejected with an MTU-exceeded error
rather than being sent.
### Startup Readiness
At startup the transport validates the configured `socks5_addr` and then
probes the SOCKS5 port to wait for `nym-socks5-client` to become ready,
using exponential backoff (starting at 1 second, capped at 10 seconds
between attempts) up to `startup_timeout_secs` (default 120 seconds). If
the proxy does not become reachable within that window, the transport
logs a warning and starts anyway; outbound connections then fail until
the `nym-socks5-client` becomes available.
### Session Independence
Same as TCP and Tor: loss of a Nym connection does **not** tear down the
FIPS peer. Noise keys, MMP state, and FSP sessions survive reconnection.
### Configuration
The Nym transport block (`transports.nym.*`) has the following fields:
| Field | Default | Description |
| ----- | ------- | ----------- |
| `socks5_addr` | `127.0.0.1:1080` | Address (host:port) of the local nym-socks5-client SOCKS5 proxy |
| `connect_timeout_ms` | `300000` | Outbound SOCKS5 connect timeout in milliseconds (300s) |
| `mtu` | `1400` | Maximum FIPS packet size for Nym connections, in bytes |
| `startup_timeout_secs` | `120` | Seconds to wait for nym-socks5-client to become ready at startup |
The Nym transport requires an external `nym-socks5-client`. Named
instances are supported for multiple proxy endpoints. Unknown
configuration keys are rejected.
### Statistics
The Nym transport exposes per-instance counters covering successful
send/receive, send/receive errors, connection establishment, SOCKS5-level
errors, connect timeouts, and MTU rejections.
## Discovery
Discovery determines that a FIPS-capable endpoint is reachable at a given
@@ -725,7 +841,8 @@ TransportType {
}
```
Predefined types exist for UDP, TCP, Ethernet, WiFi, Tor, and Serial.
Predefined types exist for UDP, TCP, Ethernet, WiFi, Tor, Nym, BLE, and
Serial.
### Congestion Reporting
@@ -750,6 +867,7 @@ on all forwarded datagrams.
| UDP | `SO_RXQ_OVFL` kernel drop counter | `recvmsg()` ancillary data on every packet |
| TCP | Not implemented | Returns `None` (TCP handles congestion internally) |
| Tor | Not implemented | Returns `None` (TCP handles congestion internally) |
| Nym | Not implemented | Returns `None` (TCP handles congestion internally) |
| Ethernet | Not implemented | Returns `None` |
### Transport Addresses
@@ -780,6 +898,7 @@ transitions through `Starting` to `Up` (operational). `stop()` moves to
| Ethernet | **Implemented** | AF_PACKET SOCK_DGRAM, EtherType 0x2121, beacon discovery, Linux only |
| WiFi | **Implemented** (via Ethernet transport, infrastructure mode) | mac80211 translates 802.11↔802.3; broadcast beacons unreliable through APs |
| Tor | **Implemented** | Outbound SOCKS5, inbound via onion service, .onion and clearnet addressing |
| Nym | **Implemented** | Outbound-only SOCKS5 through nym-socks5-client, mixnet anonymity, IP/hostname addressing |
| BLE | **Implemented** (Linux/glibc only; experimental) | L2CAP CoC, ATT_MTU negotiation, per-link MTU; musl/macOS/Windows skip |
| Radio | Future direction | Constrained MTU (51–222 bytes) |
| Serial | Future direction | SLIP/COBS framing, point-to-point |
docs/design/port-advertisement-and-nat-traversal.md
+1 -1
View File
@@ -526,7 +526,7 @@ own.
| Failure | Symptom | Mitigation |
| --- | --- | --- |
| Symmetric NAT (one side) | Punch timeout | Retry with port-prediction heuristics; otherwise fall back to a relay or different transport |
| Symmetric NAT (one side) | Punch timeout | Retry with port-prediction heuristics; otherwise fall back to an application-level relay |
| Symmetric NAT (both sides) | Punch timeout | Application-level relay required |
| Relay latency > 60 s | Stale reflexive address | Use low-latency relays; consider self-hosted relay |
| Relay does not support ephemeral kinds | Signaling events persist | Use NIP-40 expiration + NIP-09 deletion as fallback |