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Groups and gateways

In ptp mesh the root topic is the group. Everyone who sets the same root topic forms one island, and nothing is delivered across groups. A gateway (GW) is that group's RF entrance, and one group can have several of them.

To join, put one of the strings below into the root topic field described in Join.

Public groups

Root topic What it is
ptp/commons The shared group. A public island anyone can read and write. Start here if unsure
ptp/akiba-pcn The Akihabara line. Fully isolated from commons

Those two are the only published groups. You can create your own instantly by using ptp/<any-name> (no server-side registration). That island connects to nobody else, though, so announce the name if you want company.

A root topic is a partition, not a secret

Anyone who knows the root topic can join — it is a soft partition. If you want the contents hidden, add a named channel with your own PSK on top of the group. Think of it as two layers: delivery is the topic, secrecy is the PSK.

Permanent gateways

If a gateway is within RF range you can join with no MQTT setup at all. Listed here are the permanent gateways we run.

For what is up right now, use meshmap

This page lists locations and groups. For live status check meshmap.net (see Public map for how to get listed).

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Pins mark a publicly shareable landmark (a station, typically), not an exact address.

Beyond these, gateways run by other participants — in Ibaraki (Mito–Hitachinaka) and elsewhere — are connected to ptp/commons. They are not ours to list. For actual RF coverage, meshmap.net is closer to reality.

Getting your gateway listed

If you run a permanent gateway and are happy to be listed, say so on the Discord linked from Links. Listing is optional — the bridge works the same either way.

What we need:

  • A landmark location you are willing to publish (station or area name — we do not list home addresses)
  • The root topic you use (e.g. ptp/commons)
  • preset / slot (everything here runs LongFast / slot 12)
  • Uptime (24/7, offline at night, …)

Which server they live on

All groups live on the ptp mesh server, which is separate from the official broker.

Host Contents
ptp mesh (here) 160.16.104.222:1883 ptp/commons / ptp/akiba-pcn
Official broker mqtt.meshtastic.org Public meshes worldwide. The public map is fed from here

ptp-bousai is a channel, not a group — it flows inside ptp/commons. (Its source data is taken from the JPEQ channel on the official broker.)

How topics are formed

For people who want to look at the broker with an MQTT client. Topics are derived mechanically from the node's own settings.

<root topic>/2/e/<channel name>/<gateway node ID>

e.g. ptp/commons/2/e/LongFast/!e0f79774
     ptp/commons/2/e/ptp-bousai/!626f7573
     ptp/commons/2/e/PKI/!6b626f74        ← encrypted direct messages
  • 2/e is a fixed part meaning "protocol v2, encrypted"
  • The channel name goes in verbatim, so a stock primary channel shows up as LongFast
  • The last element is the gateway that relayed it, not the originating node
  • PKI carries direct messages. Nobody but the two parties can decrypt the contents

Subscribe to ptp/# for everything, or ptp/commons/# for just that group. Credentials are the same as in Join (the friend account).

commons is a public group

Anyone can read and write it, and the root topic string is visible to anyone who connects. Keep anything sensitive in your own group with your own PSK.