What does anyone prevent from doing this?

[Mellnik]

According to bitnodes.io there are around 6500 nodes. Why doesn't a millionaire or the government just buy 6000 IP addresses and setup 6000 nodes with a faked blockchain?

Would this give them the possibility of endless amount of Bitcoin and reversing transactions by spreading wrong blockchain data?

[L0uis]

No. Running a node is not the same as mining.

[Honeybooboo]

Why would anyone want to do this if it is even possible? And even if they did they'd be ruining the system thus making bitcoin worthless so it's pointless.

[roslinpl]

According to bitnodes.io there are around 6500 nodes. Why doesn't a millionaire or the government just buy 6000 IP addresses and setup 6000 nodes with a faked blockchain?

Would this give them the possibility of endless amount of Bitcoin and reversing transactions by spreading wrong blockchain data?

To do that they need > 51% of a hash power not 51% of nodes.

And ghash.io pool have more than 51% of total hash power. And they signed a paper that they will never do 51% attack.

I imagine it is possible for the government to buy as many miners as possible and posses >51% of total hash power but what would be their reason?

[Mellnik]

According to bitnodes.io there are around 6500 nodes. Why doesn't a millionaire or the government just buy 6000 IP addresses and setup 6000 nodes with a faked blockchain?

Would this give them the possibility of endless amount of Bitcoin and reversing transactions by spreading wrong blockchain data?

To do that they need > 51% of a hash power not 51% of nodes.

And ghash.io pool have more than 51% of total hash power. And they signed a paper that they will never do 51% attack.

I imagine it is possible for the government to buy as many miners as possible and posses >51% of total hash power but what would be their reason?

Bitcoin dominates traditional fiat currency in any imaginable way, just the mass adopition has yet not arrived. If the government looses control over money a big part of power goes with it too.
Destroying Bitcoin should be #1 on Govts TODO list before it's too late. Not that I would like it to happen but we all know the criminal country, USA, headed by the master crook Barack Osama.

Oh, they signed a paper? Well then, we are 100% safe of course!

[SimplisticStu]

According to bitnodes.io there are around 6500 nodes. Why doesn't a millionaire or the government just buy 6000 IP addresses and setup 6000 nodes with a faked blockchain?

Would this give them the possibility of endless amount of Bitcoin and reversing transactions by spreading wrong blockchain data?

To do that they need > 51% of a hash power not 51% of nodes.

And ghash.io pool have more than 51% of total hash power. And they signed a paper that they will never do 51% attack.

I imagine it is possible for the government to buy as many miners as possible and posses >51% of total hash power but what would be their reason?

Bitcoin dominates traditional fiat currency in any imaginable way, just the mass adopition has yet not arrived. If the government looses control over money a big part of power goes with it too.
Destroying Bitcoin should be #1 on Govts TODO list before it's too late. Not that I would like it to happen but we all know the criminal country, USA, headed by the master crook Barack Osama.

Oh, they signed a paper? Well then, we are 100% safe of course!

Agree with this 100%, Governments all over the world would love to see BTC fail as it's a threat to their currency full stop it's just not a huge threat to them right now but they know that the threat is growing everyday which is why they are watching BTC so closely.

I'm sure they know about the 51% attack and have possibly reviewed it already. Or maybe it's in a classified file labelled "Takedown Bitcoin" ready to be put into action.

[DannyHamilton]

According to bitnodes.io there are around 6500 nodes.

I suspect that list is inaccurate.

Why doesn't a millionaire or the government just buy 6000 IP addresses and setup 6000 nodes with a faked blockchain?

Because they'd be spending a lot of money, and getting no benefit from it.  You might as well ask why a millionaire or the government doesn't just shred and burn lots of money.

Would this give them the possibility of endless amount of Bitcoin

No.  There will never be more than 21 million bitcoins. Therefore, it is impossible for someone to have "endless" amount of bitcoin. Setting up nodes does not earn a person any bitcoin at all, so they wouldn't get any bitcoin.

and reversing transactions

No.  Owning nodes does not allow you to reverse transactions.

by spreading wrong blockchain data?

Their "wrong blockchain data" would be invalid, and therefore would be ignored by the rest of the network.  Any node that received multiple "wrong blocks" from them would eventually block connections from those bad nodes.  Eventually the bad nodes would be isolated and no longer connect to many peers on the real bitcoin network at all.

[picolo]

According to bitnodes.io there are around 6500 nodes. Why doesn't a millionaire or the government just buy 6000 IP addresses and setup 6000 nodes with a faked blockchain?

Would this give them the possibility of endless amount of Bitcoin and reversing transactions by spreading wrong blockchain data?

To do that they need > 51% of a hash power not 51% of nodes.

And ghash.io pool have more than 51% of total hash power. And they signed a paper that they will never do 51% attack.

I imagine it is possible for the government to buy as many miners as possible and posses >51% of total hash power but what would be their reason?

Bitcoin dominates traditional fiat currency in any imaginable way, just the mass adopition has yet not arrived. If the government looses control over money a big part of power goes with it too.
Destroying Bitcoin should be #1 on Govts TODO list before it's too late. Not that I would like it to happen but we all know the criminal country, USA, headed by the master crook Barack Osama.

Oh, they signed a paper? Well then, we are 100% safe of course!

It is a bit more complicated, the governement cannot do whatever it wants out in the open and they usually don't go as far as asking their secret services to destroy a new technology.

[matt4054]

Don't forget the crypto in cryptocurrency. Just because you get to control the majority of the nodes doesn't mean you can start pretending anything is true. The network is there to relay messages, typically signatures, that can be mathematically tested, and every sane node does it.

So it wouldn't be very useful for the government (that evil gov't...) to invest in IPv4 addresses, not to mention the fact that they have many more at hand already ;-)

[picolo]

Don't forget the crypto in cryptocurrency. Just because you get to control the majority of the nodes doesn't mean you can start pretending anything is true. The network is there to relay messages, typically signatures, that can be mathematically tested, and every sane node does it.

So it wouldn't be very useful for the government (that evil gov't...) to invest in IPv4 addresses, not to mention the fact that they have many more at hand already ;-)

It is a bit surprising that there is only 6500 nodes...Running bitcoin-qt validates as a full node?

[matt4054]

It is a bit surprising that there is only 6500 nodes...Running bitcoin-qt validates as a full node?

Yes, but if you can't be reached from the outside (e.g. NAT + no UPnP, firewalled), your node may be ignored/invisible

[twister]

According to bitnodes.io there are around 6500 nodes. Why doesn't a millionaire or the government just buy 6000 IP addresses and setup 6000 nodes with a faked blockchain?

Would this give them the possibility of endless amount of Bitcoin and reversing transactions by spreading wrong blockchain data?

To do that they need > 51% of a hash power not 51% of nodes.

And ghash.io pool have more than 51% of total hash power. And they signed a paper that they will never do 51% attack.

I imagine it is possible for the government to buy as many miners as possible and posses >51% of total hash power but what would be their reason?

I don't know what is 51% attack and what exactly this means but I don't like the sound of this. Does this means that ghash.io pool controls  bitcoin?

[DannyHamilton]

I don't know what is 51% attack and what exactly this means but I don't like the sound of this.

https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_computing_power

It's a theoretical attack whereby an entity that controls enough hash power can, for the time that he is in control, exclude and modify the ordering of transactions.

Does this means that ghash.io pool controls bitcoin?

ghash.io is a pool.  They don't control all of the hash power in the pool.  Much of that hash power is provided by the individual miners that are members of the pool.  According to this link ( https://blockchain.info/pools ) they only have access to about 8% of the total network hash power right now. If a pool that has access to a large amount of hash power started "excluding and modifying the ordering of transactions", they would likely find that many of their mining members would leave the pool.

Note that having a large amount of hash power does NOT generally allow someone to do any of the following:

• Reverse other people's transactions
• Prevent transactions from being sent at all (they'll show as 0/unconfirmed)
• Change the number of coins generated per block
• Create coins out of thin air
• Send coins that never belonged to him

[MichaelBliss]

According to bitnodes.io there are around 6500 nodes. Why doesn't a millionaire or the government just buy 6000 IP addresses and setup 6000 nodes with a faked blockchain?

Would this give them the possibility of endless amount of Bitcoin and reversing transactions by spreading wrong blockchain data?

A billionaire or government would do far better buying up the big mining operations / chip producers.  I think either way they would really damage bitcoin, making the plan a potential scenario for destroying Bitcoin, but not cornering the market.

If the government we're talking about is China, they could conceivably just take over the mining company and not have to pay for it even.   Not to profit via Bitcoins, but to mess Bitcoin up well and good.  Every move has a counter-move however, so it's hard to imagine anyone getting very far.

[twister]

I don't know what is 51% attack and what exactly this means but I don't like the sound of this.

https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_computing_power

It's a theoretical attack whereby an entity that controls enough hash power can, for the time that he is in control, exclude and modify the ordering of transactions.

Does this means that ghash.io pool controls bitcoin?

ghash.io is a pool.  They don't control all of the hash power in the pool.  Much of that hash power is provided by the individual miners that are members of the pool.  According to this link ( https://blockchain.info/pools ) they only have access to about 8% of the total network hash power right now. If a pool that has access to a large amount of hash power started "excluding and modifying the ordering of transactions", they would likely find that many of their mining members would leave the pool.

Note that having a large amount of hash power does NOT generally allow someone to do any of the following:

• Reverse other people's transactions
• Prevent transactions from being sent at all (they'll show as 0/unconfirmed)
• Change the number of coins generated per block
• Create coins out of thin air
• Send coins that never belonged to him

Thanks for link and the explanation. After taking everything into consideration I would say if ghash.io were to use their power they could halt things by not allowing transactions to confirm and double spend their own transactions.

But as you said they depend on individual miners for their whole power and if they did this others might object and leave which would result in them losing the power needed for attack in the first place.

So I guess we're safe. For now.

[jonald_fyookball]

it's not a pool..it's the aggregate unknown.  but yes it is good to know who mostly controls that.

[Bizmark13]

GHash.IO did have over 50 percent of the total mining power at one point, although it is no longer true now.

What OP is describing is a Sybil attack. The immediate precursor to Bitcoin - Nick Szabo's Bit Gold, was vulnerable to this exact problem as it relied on the percentage of honest vs. hostile nodes to enforce the correct version of the blockchain. Satoshi improved upon this design by making hash power the determinant of network authority. His other major innovation was the adjusting difficulty algorithm.

[bigcrypto]

the problem is about hashing power, and it is really difficult to control 51% of hash power

[picolo]

the problem is about hashing power, and it is really difficult to control 51% of hash power

So what could you do if you have more than 50% of the nodes?

By the way you would need to get more than 3250 nodes to have 50% of the nodes because there are already 6500 nodes so if you get 3250 you would only have 3250/(6500+3250) % of the nodes so a third of them.

[peligro]

The nodes can't decide anything. Its the miners who can decide which transaction to use.

The attack is instead possible if the government instead manages to bribe or blackmail the biggest mining pools.