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Curious to know what the difference between reachable nodes and total nodes is? How many total Bitcoin nodes are there?
For example, it doesn't look like Umbrel Bitcoin nodes are incorporated into this 'reachable node' metric... I believe there are at least 15,000 of them but wonder what makes them 'unreachable'?
Specifically referring to the Bitcoin Core nodes that Umbrel users run to set up their Lightning nodes
Unreachable nodes don't or can't accept incoming connections. By default, I believe Umbrel nodes do accept incoming over Tor so they should be represented in that purple Tor section of 7463 nodes. Umbrel might be measuring their node count using something other than reachability, e.g. number of installs.
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Ahh ok, makes sense. Are there also other types of nodes (not affiliated with Umbrel) that are missing from this network map?
I've seen some articles like this (https://bitcoinist.com/bitcoin-network-surpasses-100000-nodes-new-data-shows/) claiming there are 100,000 nodes... but not sure what the distinction between listening nodes and reachable nodes is.
Are the two mutually exclusive?
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I do suspect the map is incomplete. Reachable nodes are very likely to be in the minority of nodes given the way routers work - it requires additional configuration explained here https://bitcoin.org/en/full-node#enabling-connections.
Listening and reachable mean the same thing in this context - they accept/listen/can receive incoming connections from peers. In contrast, unreachable/non-listening nodes establish only outgoing connections to peers.
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