Johnathan Corgan
87f0678ce0
start_service switched dnsmasq's .fips forwarding to the gateway's port
before the gateway ran. A gateway that then failed, on a config it could
not parse or on a NAT or route error after binding, left every LAN
client's .fips lookups going to a port nothing held, until someone
started the gateway by hand; procd gives up respawning after five
failures and says nothing.
procd now runs the init script's supervise command, which starts the
gateway, switches dnsmasq to its port once the gateway's own process holds
a socket bound there, and switches it back to the daemon's port when the
gateway exits for any reason, passing procd's SIGTERM on so the gateway can
clean up. Ownership is checked by matching a socket inode for the port in
/proc/net/udp{,6} against the gateway's open descriptors, so a port held by
something else, such as an mDNS responder on 5353, is never mistaken for the
gateway. supervise records the gateway's pid in /var/run/fips-gateway.pid,
and an exiting instance skips the swap back only when the gateway named
there, the one procd started in its place, holds the port. Every change to
the dnsmasq entry is made under one lock, so a stopping and a starting
gateway cannot interleave. stop_service still swaps back as before. The
exit status is the gateway's, so procd's respawn behaves as it did.
procd sends SIGTERM to the supervise shell and, five seconds later, SIGKILL
to that shell alone, so a gateway slow to stop would outlive it, holding its
port. supervise kills the gateway three seconds after passing the SIGTERM
on, and stops its watcher as soon as the gateway is gone.
A new scenario runs the command start_service hands procd against stub
gateways that hold their socket themselves and exit before binding, fail
after binding, are stopped by SIGTERM, or ignore it, against a port taken by
another process, and against a swap back with a process other than the
successor holding the port, and checks dnsmasq ends on the daemon's port
each time.
Tutorials
If you have just installed FIPS, this is where to start. The tutorials below take you from a freshly-installed daemon to a node that:
- Has joined the public test mesh and can reach other nodes on it.
- Carries a stable identity that other operators can address.
- Discovers peers — and is discoverable — over Nostr.
- Hosts and consumes real services across the mesh.
Each tutorial is a complete, working session at the keyboard. You configure something, restart the daemon, watch it come up, and verify the result. The point is to build muscle memory, not to cover every option.
Read them in order. Each tutorial assumes the state the previous one left you in. If you skip ahead, the cross-references that lead you back may not match what you have on disk.
The new-user progression
| # | Tutorial | What you'll do |
|---|---|---|
| 1 | join-the-test-mesh.md | Add one public test peer to your config, watch the link come up, ping that peer and a second mesh node it routes you to. The starting point for everything else. |
| 2 | persistent-identity.md | Pin your daemon to a stable Nostr keypair so your address stops changing on every restart. Other operators can now add you to their peers: lists; the services you host get a fixed name. |
| 3 | resolve-peers-via-nostr.md | Stop hard-coding peer addresses. Drop the address line from your peer entry and let the daemon look up the current endpoint from public Nostr relays at dial time. |
| 4 | advertise-your-node.md | Publish your own UDP endpoint to Nostr so any operator who knows your npub can reach you, with a short final section on udp:nat best-effort hole-punching for nodes without a directly reachable UDP endpoint. |
| 5 | open-discovery.md | Switch to policy: open and let your peer list populate itself from the ambient fips-overlay-v1 namespace. Hands-off mesh participation. |
| 6 | reach-mesh-services.md | Drive ordinary IPv6 tools — ping6, nc, traceroute6, curl, ssh — at mesh nodes by <npub>.fips. Get a feel for the daemon's IPv6 adapter, which makes unmodified IPv6 software work over the mesh. |
| 7 | host-a-service.md | Bring up an HTTP server bound to fips0 so mesh nodes can reach it, with a deliberate exposure decision (mesh-only vs every interface), and the mesh firewall as a default-deny baseline. The peer ACL (a separate, transport-layer control over which npubs may peer with your node) is briefly mentioned alongside. |
| 8 | ground-up-mesh.md | Bring up a second deployment mode: two devices joined by Ethernet (or WiFi, or BLE) with no IP infrastructure between them. The mesh emerges from layer 2 up. Coexists with overlay peers — the same daemon can carry both. |
After tutorial 8 you have a fully participating mesh node that reaches services hosted by other mesh nodes and hosts services of its own, with identity, discovery, reachability, an explicit exposure policy, and an understanding of both deployment modes — overlay on top of existing IP, and ground-up where the mesh is the network.
There are also two side trips you can take:
-
ipv6-adapter-walkthrough.md — trace one
sshfrom DNS query through session setup to the far-side TUN, usingfipstopandfipsctlto watch each step. Optional, but if you like seeing how the pieces fit together, this is the doc that shows you. Take it any time after tutorial 1. -
native-api-walkthrough.md — write a program against the experimental native datagram API, addressing a peer by public key and port with no IPv6 emulation and no TUN. Runs two throwaway nodes on one machine, so it needs no mesh and no root, and you can take it without doing the tutorials first.
Advanced
These are not part of the new-user progression. They assume you have already worked through the tutorials above and now want to fold FIPS into a wider network deployment.
- deploy-fips-gateway.md — Stand up a
fips-gatewayon an OpenWrt access point so unmodified LAN hosts can reach<npub>.fipsdestinations through a DNS- allocated virtual IPv6 pool and kernel nftables NAT, with no per-host FIPS install. Also walks through one inbound port forward exposing a LAN service to mesh peers. Aimed at operators bridging a LAN segment into the overlay from the edge router. For a non-OpenWrt host the same deployment is in ../how-to/deploy-gateway.md.
When to use the how-to guides instead
The tutorials here walk through one specific path each. The how-to guides under ../how-to/ are the operator recipes — alternative provisioning paths, less-common configurations, troubleshooting techniques. Once you have the shape of FIPS in your head from these tutorials, the how-tos are where you'll go to look up "how do I do X?" without being walked through the surrounding context.