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fips/docs/how-to/deploy-tor-onion.md
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

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Markdown

# Deploy a Tor Onion Service for FIPS
This guide covers running a Tor onion service that accepts inbound
FIPS peer connections.
For the Tor transport's design and the bridge-node pattern (running
Tor and UDP simultaneously), see
[../design/fips-transport-layer.md](../design/fips-transport-layer.md).
For the full `transports.tor.*` config knob inventory, see
[../reference/configuration.md](../reference/configuration.md).
## Inbound modes
FIPS supports two inbound Tor modes. (A third mode, `socks5`, is
outbound-only and not covered here.)
- **`directory` mode** *(recommended)*. Tor manages the onion
service via `HiddenServiceDir` and `HiddenServicePort` directives
in `torrc`. FIPS reads the resulting `.onion` hostname from a
file and binds a local TCP listener for Tor to forward inbound
connections to. No control-port interaction is required, which
makes this mode compatible with Tor's `Sandbox 1` seccomp-bpf
hardening.
- **`torrc` requires:** `HiddenServiceDir` + `HiddenServicePort`.
- **`control_port` mode**. FIPS speaks to Tor's control port to
create an ephemeral onion service at startup (`ADD_ONION`). The
onion key lives only for the lifetime of the FIPS daemon's
control-port session. This mode is **incompatible** with
`Sandbox 1` — the sandbox forbids control-port-driven onion
service management.
- **`torrc` requires:** `ControlPort` (typically the Unix socket
`/run/tor/control`) and a usable auth method
(`CookieAuthentication 1` is the common choice).
Pick `directory` unless you have a specific reason to prefer
`control_port`. The rest of this guide covers `directory` mode
end-to-end.
## Prerequisites
- Tor daemon installed and running (Debian/Ubuntu: `apt install tor`)
- FIPS daemon configured and able to start
- Operator access to `/etc/tor/torrc` (or a drop-in under
`/etc/tor/torrc.d/`)
## Step 1: Configure Tor's HiddenServiceDir
Add the following to `/etc/tor/torrc`:
```text
HiddenServiceDir /var/lib/tor/fips
HiddenServicePort 8443 127.0.0.1:8444
```
`HiddenServiceDir` tells Tor where to store the onion service's
private key and `hostname` file. `HiddenServicePort` declares that
inbound TCP traffic to port 8443 of the onion address should be
forwarded to `127.0.0.1:8444` on the local host — that is where FIPS
will bind its listener.
The external port (`8443` here) is what peers will connect to over
Tor; the internal target (`127.0.0.1:8444`) is purely local and is
not directly reachable from the network.
## Step 2: Reload Tor and read the onion hostname
```sh
sudo systemctl reload tor@default # or `tor` on systems without instance support
```
After Tor processes the new config, the hostname file appears:
```sh
sudo cat /var/lib/tor/fips/hostname
# xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.onion
```
Tor regenerates the onion key only on first run (or if you remove
`HiddenServiceDir`). The `hostname` value is stable across daemon
restarts as long as `HiddenServiceDir` is preserved.
## Step 3: Verify HiddenServiceDir permissions
The directory must be readable only by the Tor user (Tor refuses to
start otherwise):
```sh
ls -la /var/lib/tor/fips
# drwx------ debian-tor debian-tor ...
```
With the shipped Debian systemd unit, FIPS runs as root and reads
the `hostname` file directly — no permission adjustment is needed.
### Non-default deployments
If you run FIPS as an unprivileged user (custom packaging,
hardened deployment, etc.), the FIPS daemon user needs read access
to `hostname`. Options:
- Add the FIPS user to the `debian-tor` group and loosen group
read on `HiddenServiceDir` (Tor still requires the directory
itself to be `0700`, so this typically means making `hostname`
itself group-readable rather than the directory).
- Read `hostname` once at startup as root, then drop privileges.
- Copy the hostname into a path the FIPS user can read, refreshed
whenever the onion key changes.
## Step 4: Configure the FIPS Tor transport
In `/etc/fips/fips.yaml`, configure `transports.tor` with `mode:
directory`:
```yaml
transports:
tor:
mode: directory
socks5_addr: "127.0.0.1:9050"
connect_timeout_ms: 120000
mtu: 1400
advertised_port: 8443
directory_service:
hostname_file: "/var/lib/tor/fips/hostname"
bind_addr: "127.0.0.1:8444"
```
The `bind_addr` must match the *target* of the `HiddenServicePort`
directive in `torrc`. The `hostname_file` path must match
`HiddenServiceDir` plus `/hostname`.
`advertised_port` is the *virtual* onion port peers dial — i.e. the
first number on the `HiddenServicePort` line, **not** the local
target. The default is `443`; this guide uses `8443` on both sides
to match the `HiddenServicePort 8443 127.0.0.1:8444` example
above. Setting this explicitly is important if you ever flip
`advertise_on_nostr: true`: the published advert otherwise
defaults to `tor:<hash>.onion:443`, which won't match the actual
onion port.
The `socks5_addr` is the Tor SOCKS5 proxy used for *outbound*
connections to other onion services or clearnet endpoints (separate
from inbound onion service handling).
Optional monitoring knobs: `control_addr` and `control_auth` (e.g.
`/run/tor/control` and `cookie`) let the daemon read Tor's status
through the control port even in `directory` mode. They are
non-fatal on failure — the onion service still works without them.
See [../reference/configuration.md](../reference/configuration.md)
for the full key list and examples.
## Step 5: Reload the FIPS daemon
```sh
sudo systemctl reload-or-restart fips
```
At startup the daemon reads the `.onion` hostname from
`hostname_file`, binds `127.0.0.1:8444`, and announces the onion
endpoint internally. From this point inbound connections to
`<your-onion>.onion:8443` arrive at FIPS over Tor.
## Step 6: Verify
Check that the FIPS daemon log shows the onion endpoint at startup:
```sh
sudo journalctl -u fips -e | grep -i 'onion\|directory'
```
You should see a line indicating the onion address FIPS will accept
inbound connections on, and that the local bind on `127.0.0.1:8444`
succeeded.
From another node configured with the Tor transport in `socks5` or
`directory` mode, attempt to dial:
```sh
fipsctl connect <peer-npub-or-hostname> <your-onion>.onion:8443 tor
```
A successful `fipsctl show peers` afterwards on the inbound side
shows the new peer with `transport=tor`.
## Optional: advertise the onion endpoint via Nostr discovery
If `node.rendezvous.nostr.enabled: true`, set
`transports.tor.advertise_on_nostr: true` so the onion endpoint
appears in this node's published advert. See
[enable-nostr-discovery.md](enable-nostr-discovery.md) Scenario 2.
## Troubleshooting
- **Tor refuses to start with `Sandbox 1` and onion-service errors.**
`Sandbox 1` requires `directory` mode and forbids creating onion
services through the control port. Verify your `torrc` uses
`HiddenServiceDir` (this guide), not `ADD_ONION` via control port.
- **FIPS daemon fails to bind `127.0.0.1:8444`.** Another process is
already bound to that port. Either stop the conflicting process or
pick a different port and update both `torrc`'s
`HiddenServicePort` target and `fips.yaml`'s `bind_addr` to match.
- **Onion hostname is empty or missing.** Check `journalctl -u tor`
for permission errors on `HiddenServiceDir`. The directory must be
owned by the Tor user with mode `0700`.
- **FIPS daemon cannot read `hostname_file`.** File is owned by the
Tor user and not readable by the FIPS daemon user. Adjust
permissions, or copy the hostname into a path the FIPS user can
read.
## See also
- [../design/fips-transport-layer.md](../design/fips-transport-layer.md)
— Tor transport design, three modes (`socks5`, `control_port`,
`directory`), bridge-node pattern
- [../reference/configuration.md](../reference/configuration.md) —
full `transports.tor.*` configuration knob table
- [enable-nostr-discovery.md](enable-nostr-discovery.md) — Scenario 2
for advertising the onion endpoint to peers via Nostr