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Johnathan Corgan
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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.
234 lines
10 KiB
Markdown
234 lines
10 KiB
Markdown
# IPv6 Adapter Walkthrough
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You have completed [join-the-test-mesh](join-the-test-mesh.md).
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Your daemon is peered with `test-us01` and you can ping mesh
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nodes by `.fips` name. This tutorial walks the plumbing that
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makes that possible: what happens between the moment your shell
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types `ssh user@<peer>.fips` and the moment a TCP SYN arrives at
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sshd on the far side. Each step is something you can observe
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with the running daemon from the previous tutorial.
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By the end you will be comfortable reading `fipstop` output and
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you will know which design doc to consult when something looks
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off.
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> **Prerequisites.** The daemon from
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> [join-the-test-mesh.md](join-the-test-mesh.md) is running and
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> peered with at least one test-mesh node, and your host's local
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> resolver is forwarding `.fips` queries to the daemon's DNS
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> responder (the system fips-dns.service drop-in does this
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> automatically on systemd hosts).
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## The path we're tracing
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```text
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shell ──ssh──> libc resolver ──.fips──> fips DNS ──AAAA──> fd97:...:test-us01
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│
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▼
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kernel IPv6 stack
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│
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▼
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fips0 (TUN)
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│
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▼
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your fips daemon
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(FSP session setup,
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FMP forwarding)
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│
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UDP / internet
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▼
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test-us01's fips daemon
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│
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▼
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fips0 (TUN)
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│
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▼
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kernel IPv6 stack
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│
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▼
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sshd
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```
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In a multi-hop mesh the middle would have additional FMP
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forwarders between your daemon and the destination. For this
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walkthrough you have a single direct link to `test-us01`, which
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keeps the trace simple.
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## Step 1: Watch the DNS resolution
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Ask the system resolver to translate `test-us01`'s npub into its
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mesh address:
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```sh
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dig npub1qmc3cvfz0yu2hx96nq3gp55zdan2qclealn7xshgr448d3nh6lks7zel98.fips AAAA +short
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```
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You should see one AAAA record returning an address such as
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`fd97:...`. The prefix is the FIPS ULA range (`fd00::/8`): only
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the leading `fd` byte is fixed, and everything after it is hash
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output derived from the npub, so the digits beyond `fd` vary per
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node.
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The query went through `systemd-resolved` (or your platform
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equivalent), which routed `.fips` queries to the daemon's local
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responder via the drop-in installed by `fips-dns.service`. To
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confirm, query the daemon directly:
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```sh
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dig @::1 -p 5354 npub1qmc3cvfz0yu2hx96nq3gp55zdan2qclealn7xshgr448d3nh6lks7zel98.fips AAAA +short
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```
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Same answer, same fast turnaround — no external DNS traffic in
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either case.
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The mapping `npub → fd00::/8 address` is deterministic. The
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responder hashes the public key into 16 bytes, prepends the
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prefix, and returns the result. There is no shared registry; the
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address space is self-allocating from the public-key namespace.
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If you ask for any non-`.fips` suffix, the responder returns
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`NXDOMAIN` — it is intentionally a stub for this single zone, not a
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recursive resolver. An unknown `.fips` name returns `NXDOMAIN` too.
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The full DNS integration is documented in
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[../design/fips-ipv6-adapter.md](../design/fips-ipv6-adapter.md).
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## Step 2: Watch the session being created
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Open `fipstop` against your daemon's control socket:
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```sh
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sudo fipstop
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```
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Press `Tab` until you reach the **Sessions** tab. Before any
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TCP traffic to `test-us01`, the table is empty (or has rows from
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earlier exchanges).
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In another terminal, kick off a TCP connection from your host
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toward `test-us01`:
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```sh
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ssh -o ConnectTimeout=5 user@test-us01.fips
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```
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(`test-us01.fips` resolves to the same address as the npub
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form via the installer's `/etc/fips/hosts` entry.)
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(It is fine if the SSH attempt fails authentication or if no
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sshd is exposed on the far side — what we want to observe is the
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session machinery firing, not a successful login.)
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In `fipstop`'s Sessions tab you should see a new row appear with:
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- `state` cycling from `initiating` to `awaiting_msg3` to
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`established` (the three FSP handshake states).
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- `display_name` showing `test-us01` (the `alias` you set in your
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`peers:` block in the previous tutorial).
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- A non-zero `last_activity_ms`.
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Once `established`, the session row stays put until idle-timeout
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expires. The traffic counters and MMP metrics tick as data flows.
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> **Watch for.** Some intermediate states may be too fast to
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> see at the default `fipstop` refresh rate of 2 s. Run
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> `sudo fipstop -r 1` for a faster refresh during the exercise.
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## Step 3: Watch the per-session metrics
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Switch to the **Performance** tab. Each established session has
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a session-layer MMP entry showing:
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- `srtt_ms` — smoothed end-to-end round-trip time. Over a
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public-internet path this typically lands in the tens of
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milliseconds; for a US-coast destination from a US client you
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might see 30–80 ms steady-state.
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- `loss_rate` — fraction of in-flight payloads inferred lost from
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counter gaps. Stays at 0 on a healthy link; small bursts during
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congestion or path changes.
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- `path_mtu` — the end-to-end MTU the session-layer MMP currently
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believes is in force. Starts at the IPv6 floor and climbs as
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PathMtuNotification echoes arrive.
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- `etx` and `goodput_bps` — derived metrics, useful as
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steady-state indicators.
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The same metrics are available without the TUI:
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```sh
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sudo fipsctl show sessions | jq '.sessions[] | {display_name, state, mmp}'
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```
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What these numbers mean is documented in
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[../design/fips-mmp.md](../design/fips-mmp.md). Briefly: SRTT is
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RFC 6298-style with α = 1/8; loss is bidirectional, inferred from
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counter gaps in MMP reports; path MTU is end-to-end-echoed with
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hysteresis on increase.
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## Step 4: Watch the link below the session
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Switch to the **Peers** tab. Each authenticated peer has its own
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link-layer MMP block, distinct from the session-layer one above.
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The link-layer metrics measure a single hop (here, your daemon
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↔ `test-us01` over UDP), independent of any session that
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traverses it.
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Compare the link-layer SRTT for `test-us01` to the session-layer
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SRTT of the session you just created. Because your reach to
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`test-us01` is one direct hop, the two should be very close —
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the session has no transit forwarders to add latency.
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If you reach a node that `test-us01` forwards to (try the
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`test-us02` ping from the previous tutorial), the session-layer
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SRTT for that destination will be measurably larger than the
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link-layer SRTT to `test-us01`. The difference is the time
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`test-us01` spent forwarding plus the hop from `test-us01` to
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`test-us02`.
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In a deeper mesh this divergence grows: link-layer SRTT measures
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the direct neighbour, session-layer SRTT measures the full
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end-to-end path.
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## Step 5: Read the relevant design docs
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You have now seen the moving parts. To go from "I can read these
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metrics" to "I understand why each one moves the way it does":
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- [../design/fips-ipv6-adapter.md](../design/fips-ipv6-adapter.md)
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— DNS responder, identity cache, TUN reader/writer, IPv6 header
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compression, MTU enforcement at the TUN boundary.
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- [../design/fips-session-layer.md](../design/fips-session-layer.md)
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— FSP session lifecycle: msg1 / msg2 / msg3, the rekey state
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machine, the drain window for old sessions during cutover.
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- [../design/fips-mmp.md](../design/fips-mmp.md) — both link-layer
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and session-layer MMP: report format, SRTT estimation,
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loss/jitter/ETX computation, the trend indicators.
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- [../design/fips-mtu.md](../design/fips-mtu.md) — what `path_mtu`
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in `show sessions` means: the proactive forward-path field, the
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reactive `MtuExceeded` mechanism, the hysteresis on increase.
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- [../design/fips-architecture.md](../design/fips-architecture.md)
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— the two-layer encryption model: link-layer Noise IK over
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each hop, end-to-end Noise XK over the session.
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## What you've learned
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- A `.fips` name resolves through a daemon-local stub responder.
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The mapping from npub to `fd00::/8` address is deterministic
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and needs no registry.
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- The kernel IPv6 stack treats the TUN adapter as an ordinary
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interface; packets to `fd00::/8` go out via that route. The
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daemon reads them off the TUN, looks up an FSP session for the
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destination (creating one if needed), and forwards them onward
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through its peers.
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- The session layer (FSP) and the link layer (FMP) each maintain
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their own MMP metrics. Session-layer metrics measure the path
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end-to-end; link-layer metrics measure a single hop. The two
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align when the destination is your direct peer; they diverge
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when traffic traverses additional hops.
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- `fipstop` exposes both views in real time. `fipsctl show sessions`,
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`fipsctl show peers`, and `fipsctl show transports` cover the
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same ground programmatically.
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When something looks off in production, the `fipsctl show *`
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queries are usually the first stop; the relevant design doc tells
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you what the numbers mean and what they should do.
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