Define Well Connected

[deadserious]

From the FAQ:

"In general, selling things that are fairly cheap (like snacks, digital downloads etc) for zero confirmations will not pose a problem if you are running a well connected node."

What makes a node well connected? 

btw, I'm assuming Node means client based on the usage of the answer in question.

[1715139344]

1715139344

[zubatej]

Bitcoin client connected to some other peers via reliable network connection.

[deadserious]

Bitcoin client connected to some other peers via reliable network connection.

I was hoping for a bit better explanation than that.

Is 2 client connections well connected?  How about 10?  30?  Is well connected the quality of the network connection or the quality of the peer network connection?  Or does it mean that the peers you are connecting to are trusted to be valid clients?

If I have a local network of 20 bitcoin clients running and all configured to connect to each other with one linking out to a single unknown external client, is any of those 20 well connected?  Does the answer change if the single external client is known to be a valid client?

[kinlo]

As long as a payment is not mined in a block, they are just floating around in all active clients, so they can be incorporated in the next block.

Once a transaction is known by a client, this client will not allow another spending of that same money.   By well connected they mean a client that can broadcast those transactions to the other clients; so the money cannot be spent twice.


Let me explain by an example:

Imagine you have a bitcoin client, only connected to one other client, the client of the attacker.   Then the attacker can send the money, your client will show it as unconfirmed.  But as you are not connected to the rest of the network, the attacker can send another payment on the real network, for the same money.     The first transaction that is mined will become permanent, and as your transaction was not visible in the global network, it will never be mined and then dropped later on:  Clients will not accept double expenses.

Does this makes any sense?

[deadserious]

It does make some sense and thanks for the detailed explanation.

I guess what I'm really trying to wrap my head around is that if I maintain a network of trusted clients that all have a connection to each other, is that better or worse "well connected" than clients that connect to random unknown clients.

But what I get from your post is that "well connected" might be better defined in fewest possible degrees of separation from miners... would that make sense?

[kinlo]

that is correct.  You should just be connected to the miner that will mine the next block.  But as you don't know who that will be, just be connected to all