Files
fips/docs
Johnathan Corgan 0611ef4c61 Add a fipsctl probe diagnostic for reachability and tree position
fipsctl probe <npub|hostname> answers, for one target, where it sits in
the spanning tree relative to us and whether we can actually reach it.
It reports our coordinates, the target's, the walk between them and the
next hop we would select, then opens an FSP session, waits for one MMP
receiver report to yield a round-trip time, and tears down what it
opened.

Nothing here changes the wire format. The probe is built entirely from
messages that already exist, and the control socket carries the new
request triplet.

The work runs as five stages that report separately: bloom, discovery,
path, session and rtt. One verdict covering several findings is what
makes an operator read source, and the distinctions are real ones. "No
peer's filter claims this address" says the mesh has never heard of the
target; "a filter claimed it and nothing answered" says the opposite,
that somebody believes the address is reachable and the lookup went
unanswered anyway. Bloom emits the lookup and settles on the gate's
answer, where a miss, a backoff suppression or a zero fanout ends the
probe; discovery waits for the coordinates and owns the ladder timeout.
"Lookup never resolved" and "resolved but the handshake never completed"
part the same way further down. Each stage keeps the reasons it owns, so
no discriminator is lost and none sits on a stage that cannot produce
it.

The path is computed from coordinates, not observed. The output says so
in those words: nothing traverses the mesh to confirm the hops, and a
route display that reads like traceroute output would be believed as
one. A real per-hop trace needs a new wire message, so it is not on this
branch.

The probe is a daemon-side job advanced on the tick, not a blocking
control call. The control socket has a five second timeout and its
dispatch is awaited inline in the rx loop, so a handler that waits for a
handshake would stall the data plane. Start, poll and cancel each return
immediately and fipsctl hides the polling. The job is stepped once at
the end of admission rather than left for the next tick, which
admission can do because the probe commands take the command path and
therefore already run on the rx loop; otherwise every probe spent up to
a full tick period of its own budget before a single message left the
node, which against a one-second tick meant the first three polls of an
already-cached target showed nothing happening.

It cleans up after itself, and that is the part built to be defended
rather than assumed. A session that existed before the probe started is
never torn down, ownership is decided at the moment of action rather
than once at the beginning, re-checked before teardown, and dropped if
our entry is replaced or adopted by traffic underneath us. Removing the
ownership guard reds eleven tests.

The client renders each poll rather than waiting for the end. The daemon
was already progressive, returning the whole report on every poll with
each stage carrying its own verdict as it reaches one, so a client that
waited for `state == "done"` made a probe spending seventeen seconds in
a lookup ladder look identical to one that was hung. On a terminal the
stage block is redrawn in place with a spinner and a running elapsed on
whichever stage is working. Piped or redirected there is no cursor to
move, so each row prints once, at the moment it settles, and the
transcript ends up the same block a terminal leaves behind. `--json` is
untouched and still emits exactly one document at the end, so a script
parsing the report does not have to skip past progress output.

Four things the rendering has to get right, none of them automatic:

- A running stage may only report what the daemon has observed, and must
  never preview an outcome. Every settled text keys on `reason`, which
  is null while a stage runs, so the success arm renders for a stage
  that has not succeeded and a running session row would claim the
  handshake completed.
- The elapsed column comes from the daemon's clock throughout, the
  running stage's figure being the report's elapsed less the stages
  already accounted for, so the numbers a viewer watches are the ones
  the final report prints.
- A frame shorter than the last one blanks the rows it no longer covers
  and walks the cursor back over them, or the previous frame's tail
  stays on screen under a report that has stopped mentioning it.
- The discovery ladder is read from the report rather than assumed,
  since it is configuration and a node may not be using the default. One
  line per request sent, with the timeout that attempt was given and
  whether it drew a reply, the last animating while it is in flight.

Below the block, the tree walk is one line: self, up through the least
common ancestor, down to the target, with the ancestor emphasised on a
terminal and left plain in a pipe or a file. Naming the ancestor alone
left the reader to assemble the route from it and the two coordinate
lines above. Where the target is itself the ancestor there is no descent
and the line ends on the emphasised address.

Stages that were never attempted print no row. A failure marks
everything behind it not reached, and saying that three more times adds
nothing to the failed row that already said it. The rule keys on
`not_reached` rather than on the position of the failure, because those
are not the same set: a failed path stage does not stop the probe, since
the preview touches nothing and the session can still succeed where it
named no next hop, so the rows behind that one describe work that really
happened. A skip keeps its row for the same reason, being a result
naming why a stage was unnecessary rather than an absence. A probe that
fails before the path stage prints no path section, which had been
restating the failure as "no coords" and "no next hop".

Two counts the discovery stage gets right that are easy to get wrong. It
marks itself running while it waits, where publishing `pending`
throughout would read to a poller as a stage that has not started. And
the first attempt is counted when the request is sent rather than when
the pending table is next observed, since a lookup answered inside one
tick never appears in that table and the fastest case would report no
attempts at all.

Two honest gaps: the HopNotSendReady branch is not reached by any test,
and the concurrent-probe cap counts only unfinished jobs without a test
covering that filter.

Adds 63 tests across 32 files.

One changelog entry under Added, describing the released state: the five
stages and why they are separate, the session the probe opens and the one
it must not tear down, the path being computed rather than observed, the
three control commands and why they cannot block, and the two rendering
modes. It says in as many words that the wire format is unchanged.
2026-08-21 05:24:53 +00:00
..
2026-08-09 13:41:03 +00:00

FIPS Documentation

FIPS (Free Internetworking Peering System) is a self-organizing encrypted mesh network built on Nostr identities, capable of operating over arbitrary transports — local networks, the public internet, Tor, Bluetooth, or point-to-point links — without central infrastructure.

With FIPS, your machine becomes a node in the mesh with a self-generated cryptographic identity. There are two ways to deploy it.

As an overlay on top of existing IP networks, FIPS lets your node reach any other FIPS node wherever it sits — behind a NAT, on a different ISP, on a phone over cellular, on a laptop with only Bluetooth in range, or behind a Tor onion. The mesh forwards IPv6 traffic transparently and end-to-end encrypted, with no central VPN concentrator or coordinating server.

From the ground up over raw Ethernet, WiFi, or Bluetooth, FIPS provides a complete permissionless network without any pre-existing IP infrastructure, ISP, or DNS. Any node that joins the link gets routable IPv6 addresses, peer discovery, and a path to every other node automatically.

Either way, existing networking software runs over it unchanged: SSH, HTTP servers, file transfer, anything IPv6-native works the same way it would on a local network.

New to FIPS? Start with the Getting Started guide.

Documentation Sections

Tutorials

If you are starting from scratch and want a guided path to a working mesh, go here.

How-To Guides

If you have a specific task in mind — enabling a feature, deploying a component, diagnosing a problem — go here.

Reference

If you need to look up wire formats, configuration keys, command flags, or counter inventories, go here.

Design

If you want to understand how the mesh self-organizes, why FIPS makes the choices it does, or how the pieces fit together, go here.