Had a thought... what if one group controlled over 50% of Bitcoin nodes? What could they do? Could they perform an eclipse attack by hiding blocks from others? Or would using something like Bitnode fix this issue? But then again, could Bitnode still suggest malicious nodes?
If someone controls over 50% of nodes, they could technically initiate a 51% attack. But really, they could mainly influence transaction flow and maybe double-spend coins. Though most attacks rely on hash power, some eclipse attacks could definitely happen.
Yeah, but double-spending needs the ability to create blocks that overwrite the main chain, right? That comes from mining power, not just running nodes. And what do you mean by ‘block and kind of delay transactions’?
Good point. To run that many nodes, you'd likely need some hash power too. Otherwise, you’d just have regular computers totally synced with the blockchain without any real mining power. And for delayed transactions, they could just drop a transaction broadcast and you’d have to resend it.
Network disruption could happen, yeah. Blocking certain transactions would be straightforward as a censorship tool. Sybil attacks don't really work on Bitcoin because of PoW, but they might fake support for a soft fork, right?
Exactly. Eclipse attacks, though, those can enable double-spends if the victim accepts zero-confirmation transactions. If an attacker isolates a node, that node only sees what the attacker shows it.
Bitnode isn't a perfect solution. It just tracks nodes that accept connections, not the peer connections themselves. A malicious actor could still show up as legitimate.
So, as long as a node connects to at least one honest node, there’s little risk for eclipse attacks. Odds of a node getting fully eclipsed are pretty low if connections are random.
Right, if an attacker isolates nodes, they can control peer connections and flood victims with fake nodes. But only a true 51% attack can really rewrite Bitcoin’s history.
You can't even be sure you own 50% of nodes. Some are just passive watchers and don’t broadcast. Successful attacks require tons of IPs, and honest nodes blacklist the bad ones. It’s all expensive.