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Johnathan Corgan
d7f079618f
The native API's receive rule cannot tell a zero-length datagram that is the last message before a close from the close itself on SOCK_SEQPACKET, which Linux uses: reading it drains the queue, and every observation then matches a bare end of file. macOS and FreeBSD carry the flow on SOCK_DGRAM, where the empty datagram is delivered and the close is reported by the read after it. The doc comment on Received::Datagram said an empty datagram is never a close, which contradicted the limitation stated a few hundred lines below it. It now says where the exception applies, and the recv_once rationale, the FipsStream::recv rustdoc, the native API reference and the client how-to scope the limitation to Linux. The reference page's list of places where data disappears gains the send-side consequence: a program that sends an empty datagram and then drops its stream may have the daemon read it as the close, so it never reaches the peer. The datagram how-to, which counts those places, is updated to match. A new test pins the behaviour per socket type, branching on the module's socket-type constant rather than on the OS, so the documentation and the test cannot drift apart.
How-To Guides
Task-oriented, step-by-step recipes for operators with a specific goal in mind. Each guide assumes the reader already knows what FIPS is and wants to get a particular thing done — enable a feature, deploy a component, troubleshoot a class of problem.
How-to guides do not teach concepts (that is the role of design/) and do not enumerate options (that is the role of reference/). They take the reader along the shortest correct path from "I want to do X" to "X is done".
Available Guides
| Guide | Goal |
|---|---|
| enable-mesh-firewall.md | Activate the default-deny nftables baseline on fips0 |
| enable-nostr-discovery.md | Turn on Nostr-mediated discovery (3 capabilities — resolve, advertise, open — across 5 scenarios) |
| deploy-tor-onion.md | Run a Tor onion service for inbound FIPS connections |
| tune-udp-buffers.md | Set host sysctls so FIPS UDP sockets don't get clamped |
| tune-file-descriptors.md | Raise RLIMIT_NOFILE so a busy node doesn't exhaust file descriptors (EMFILE) as peer count grows |
| run-as-unprivileged-user.md | Run the daemon under a dedicated unprivileged service account (drops the default-root posture) |
| deploy-gateway.md | Manually deploy fips-gateway on a non-OpenWrt Linux host (LAN-to-mesh outbound + mesh-to-LAN inbound port-forwards). For the OpenWrt path, see the gateway tutorial. |
| troubleshoot-gateway.md | Diagnostic recipes for the gateway, organised by half (outbound, inbound, common) |
| persistent-identity.md | Provision a stable Nostr keypair so the node keeps the same npub across restarts |
| host-aliases.md | Use shortnames (test-us01.fips, my-laptop.fips) instead of full npubs by editing /etc/fips/hosts or setting peer aliases |
| set-up-bluetooth-peer.md | Configure a Bluetooth Low Energy peer link |
| set-up-80211s-mesh-backhaul.md | Link OpenWrt FIPS routers over an open 802.11s radio backhaul (FIPS provides encryption, authentication, and routing) |
| set-up-open-access-ssid.md | Broadcast the open !FIPS access SSID so phones and laptops roam onto the mesh (one ESS: save once, roam every FIPS router) |
| diagnose-mtu-issues.md | Triage MTU-shaped failures and rule out their imposters (bufferbloat, transport saturation) |
| use-the-native-datagram-api.md | Enable the experimental native datagram API and write a program that sends and receives datagrams by pubkey and port (no IPv6 emulation, no TUN). Read the fips group warning first |
| write-a-native-api-client.md | Speak the native datagram API's line protocol directly from C, Python or Go, where there is no client library |
| serve-many-peers-on-one-thread.md | Handle every native API flow from one poll loop instead of a thread per peer |