Skip to content

RagnarAP.md

Latest commit

 

History

History
213 lines (152 loc) · 8.37 KB

RagnarAP.md

File metadata and controls

213 lines (152 loc) · 8.37 KB
Raw

Ragnar AP Mode

How Ragnar gets itself onto a network, and what it does when it can't.

The short version: if Ragnar cannot join a saved network, it raises its own access point and leaves it up until you use it. Join it, tell it which network to use, and it switches over. That is the whole flow for a new box and for a box you have carried somewhere new.

Joining a network
Network name Ragnar
Password ragnarconnect
Setup page http://192.168.4.1:8000
Ragnar's address on its own AP 192.168.4.1
Client addresses 192.168.4.2 – 192.168.4.20

Join the Ragnar network from a phone or laptop and open the setup page. Pick the network you want, enter its password, and the box switches over.

Two things worth knowing. The AP does not time out — it is there whether you look after ten seconds or an hour. And Ragnar's web interface is on port 8000 only; plain http://<address> with no port opens nothing.

Taking a box somewhere new

This is the same flow. Bring a Ragnar to a summer house, an office or a hotel, power it on, and it will:

  1. look for its saved networks for about a minute;
  2. fail to find them, and raise the Ragnar AP;
  3. wait — indefinitely — for you to join and add the local network.

Old networks are kept. Back home, the box rejoins the home network on its own (see below) without you touching anything.

When AP mode starts

At boot Ragnar checks for an existing connection. Ethernet counts and is preferred; if a cable is live, Wi-Fi is left alone entirely.

Otherwise it enables the radio and gives NetworkManager 60 seconds to auto-join a saved network. If that fails, one last connectivity check runs (a real ping, not just an association) to catch a working link that the earlier checks missed. Only then does the AP come up.

When AP mode does not start

Two modes own the radio for their own purposes, and the automatic AP fallback is skipped for both. Wi-Fi searching still continues in each — only the AP is suppressed, so the box will still rejoin a network on its own if one appears.

Mode Config key Why
Wardriving wardriving_enabled Needs the radio for scanning. hostapd would take the interface over. Wardriving has its own AP, started deliberately — see below.
On-Screen Network Diagnostic Mode network_diagnostic_mode It is a field test of the network the box is on. Converting the radio into an access point mid-test invalidates every reading on the screen.

Getting back onto a known network

Once the AP is up, Ragnar keeps looking for a network it knows, and hands over when it finds one. This is what makes a router reboot a non-event.

How it looks without dropping the AP. Scanning uses a secondary adapter if one is fitted, otherwise iwlist on the AP interface — deliberately chosen so the scan does not interrupt hostapd.

Cadence. A 30-second settle after the AP comes up, then a check every 30 seconds. Measured as elapsed time, so it holds under load rather than drifting.

It will not interrupt you. Recovery is skipped entirely while somebody is connected to the AP. If you are sitting on the setup page entering a password, the box will not pull the network out from under you — however long you take.

When the AP stays up

With nobody connected, the AP is left running. Two cases still bring it down, because otherwise the box could never rejoin anything:

  • Scanning is not working on this hardware. Ragnar tracks whether a scan has recently returned any result, which separates "scanned, nothing in range" from "cannot scan at all". Only the latter falls back to dropping the AP to search the ordinary way.
  • There is at least one saved network. With none — a fresh install — there is nothing to search for and the AP is the entire point, so it stays up indefinitely.

Using a USB Wi-Fi dongle

With a second adapter the two jobs split across radios:

Radio Role
wlan0 (built-in) hosts the Ragnar access point
wlan1 (dongle) client connection and background scanning

The AP stays on the built-in radio on purpose. Not every USB dongle's driver supports AP mode, whereas the Pi's on-board chip reliably does, and 2.4 GHz is the band every phone can find.

Two things this buys you:

  • A failed join no longer costs you the AP. With one radio Ragnar must drop the AP to attempt a connection, and put it back if the attempt fails. With a dongle it joins on wlan1 while hostapd keeps running on wlan0, untouched.
  • 5 GHz becomes reachable on a Pi Zero 2 W, whose built-in radio is 2.4 GHz only. Without a dongle a 5 GHz-only network cannot be joined at all.

Once the uplink is up the setup AP shuts down. It is not left broadcasting: the box is reachable through the dashboard by then, and the default AP password is published in this documentation.

On a single-radio box the client and AP interfaces resolve to the same adapter and behaviour is exactly as described everywhere else in this document.

The wardriving AP is a different thing

The KEY1 phone-access AP used during wardriving is separate from everything above:

  • it is started deliberately by the user, not as a fallback;
  • it advertises no gateway and no DNS, so a joined phone keeps using its own cellular data;
  • it serves the minimal live wardriving page rather than the setup portal;
  • the automatic logic never tears it down — it stays up until KEY1 is pressed again.

See the Wardriving Guide.

Settings

Key Default Meaning
wifi_ap_ssid Ragnar AP network name
wifi_ap_password ragnarconnect AP password
wifi_default_interface auto Which radio is the built-in / AP interface
wardriving_enabled false Suppresses the automatic AP
network_diagnostic_mode false Suppresses the automatic AP

Timings live in wifi_manager.py: a 60-second join attempt, a 30-second settle (ap_recovery_grace), a 30-second recovery cadence (ap_reconnect_check_interval), and a 300-second window (scan_trust_window) after which a scan that has returned nothing is treated as a broken scan rather than an empty sky.

Change the AP password if the box lives somewhere untrusted. The default is public — it is printed above.

Troubleshooting

The setup portal appears instead of the dashboard

If http://<box>:8000 shows the Wi-Fi Configuration Portal while the box is plainly already connected, your router hands out addresses in 192.168.4.0/24 — the same range Ragnar uses for its own AP. eero mesh systems default to this subnet.

Ragnar decides "this request came from an AP client" by checking that it holds the AP gateway address 192.168.4.1 itself, not merely that the client sits in that subnet, so an ordinary client on a 192.168.4.0/24 LAN gets the dashboard. If you are seeing the portal, update and restart:

sudo ./update_ragnar.sh && sudo systemctl restart ragnar

The Ragnar network is not in my Wi-Fi list

  • Give it a moment after power-on: the box spends about a minute trying saved networks before the AP comes up.
  • Check the box is not in wardriving or diagnostic mode — the automatic AP is suppressed in both.
  • On a box with a dongle, the AP is on the built-in radio; a dongle that is unplugged or asleep does not affect it.

The AP does not disappear on a timer. If it is missing after a couple of minutes, something failed to start rather than timed out.

It joined the network but I cannot reach it

Ragnar listens on port 8000. http://<address> alone will not open.

Nothing opens at 192.168.4.1:8000

Confirm your device actually took a 192.168.4.x address from the AP. Phones sometimes stay on cellular when a network offers no internet — the setup AP deliberately provides none, since it has no uplink to share yet.