[nullc]

This is _highly_ misleading. The actual number of nodes that they're measuring is 11,664, which is a sudden increase from a slowly declining level of about 4,400 as of a month ago.

The 196,123 number is a count of the number of distinct IP addresses being rumored between nodes. Most of them are never working garbage sent into the network by confused software, misguided would-be DOS attackers, etc.

[carbocation]

If the actual number is still doubling rapidly from a recent nadir, isn't the implication the same?

Also, for people who don't see this as natural (and I agree that it looks almost mechanical), is this a misguided "51%" attack? (Seems unlikely given that if you have the resources for that, you also probably understand how it works.) Just curious what people see this sudden change as representing.

[gwern]

> Also, for people who don't see this as natural (and I agree that it looks almost mechanical), is this a misguided "51%" attack?

No. The whole point of the POW mechanism is to frustrate cheap easy Sybil attacks where someone sets up a few thousand IPs and dictates what the network says.

[nas]

> a sudden increase from a slowly declining level

That's worrying. I'm much more concerned about a Sybil attack or similar attack on the P2P network than an attack on the cryptography. Given the current size of the ledger, the average person will not want to run a node. I guess one mitigating factor is that the mining pool operators can take steps to ensure they are well connected to each other.