A Network tab, with an internet speed test

Per machine like every other tab: the interfaces as the kernel has them
(addresses, MAC, MTU, negotiated link speed, carrier, totals, live rates from
the sampler's own sensors), the default route and resolvers, what the internet
sees of this connection, and a speed test with the last fifty results kept.

The test runs in the daemon, not the browser, so the figure is the line of the
machine in the switcher — the router's, if you switch to gate — and it carries
on when the phone locks. It measures against Cloudflare's public speed
endpoints, so there is nothing to install on any host, which is what makes it
work the same on Debian and on OpenWrt where flash is scarce.

What the measurement does and does not count:

  - Several streams, HTTP/2 deliberately off. One stream over one connection
    measures a congestion window, and HTTP/2 would put every stream back onto
    one connection and measure the same thing.
  - The first second of each phase is thrown away as the ramp.
  - A phase ends on 64 MiB as well as on four seconds, so a fast line says what
    it is without moving a gigabyte. A minimum window keeps a very fast line
    from filling the cap before there is anything to divide by.
  - Latency is the round trip less the far end's own Server-Timing. A zero-byte
    response is mostly Cloudflare's worker thinking: left in, it reported 31 ms
    for a line the edge itself measures at 3.5. Jitter is the mean change
    between consecutive probes, so one slow probe cannot run away with it.
  - The far end rate-limits by volume. So: a 20 s cooldown counted from the last
    attempt rather than the last success, streams that retry twice, the rate
    computed over the window in which bytes were actually still arriving, and a
    plain sentence when it was refused. Coasting to the end of the clock with
    nothing arriving reported a third of the truth.

The last result is published as net.internet.* sensors, each stamped with when
the test ran, so the line can be a widget, a graph, an alert or a Prometheus
series like anything else. The public address is refreshed on its own quarter
hour, which is worth having here: it is a DHCP lease and it moves.

Tests are offline — the window, the byte cap, the refusal and the cancellation
run against a local server; the route parser's byte order is pinned by a case
that would have caught the bug it did. The live measurement is behind
HAMLAB_NET_TEST=1.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -70,6 +70,7 @@ What adapts to the host, rather than assuming Debian:
 | Updates tab | apt, dnf, zypper, pacman, apk: list, refresh, upgrade, install (pacman: all or nothing) |
 | Services / timers | systemd of any age (JSON output where it exists, the plain table before v246); a clear message on hosts without systemd |
 | Disks | `lsblk`, or `/sys/block` when it's missing (busybox) or too old; SMART and ZFS only when their tools are there |
+| Network | `/proc` and `/sys` for the interfaces, addresses, link speed and default route. The speed test needs no tool installed: it measures against Cloudflare's public speed endpoints, so it works the same on Debian and on the OpenWrt router |
 | Dashboard | `/proc` and `/sys` only: hwmon or thermal-zone temps, fans, NICs, disks, mounts; empty sections where the hardware has nothing to report. UPS from whichever of `pwrstat`, NUT (`upsc`) or `apcupsd` is installed |
 | Listen address | bound with `IP_FREEBIND`, so a LAN address that isn't up yet at boot doesn't fail the start |
 | Self-update | the new build must run and load this host's config before it replaces the old one; atomic rename; the daemon then re-execs itself, so it restarts the same way under systemd, OpenRC or nothing; `hamlab.prev` kept |