<p>Yes, but this would only work if said ISP would host more than 50% of all the full nodes in the network. This is simply not the case, the nodes in the network are too widely distributed for that.</p>

CC BY-SA 3.0
2018-02-05T14:16:07.223Z
An ISP can isolate all TCP connection with the message signature corresponding to BTC protocol and completely control all the nodes under its host / letting only the nodes inside that ISP talk to eachother, is that right? 
I mean, divide and conquer, not trying to attack the whole BTC network
qkhanhpro
CC BY-SA 3.0
2018-02-05T14:03:35.493Z
2018-02-05T14:03:35.493Z
Glorfindel
<blockquote>
  <p>I came to believe that an ISP can easily detect full nodes, BTC connections and isolate them from reaching any other nodes.</p>
</blockquote>

<p>This is true. An ISP could easily block all Bitcoin traffic or, just prevent Bitcoin traffic from entering/exiting their network and isolate the nodes.</p>

<blockquote>
  <p>When and if an ISP decided to do so, they could easily perform a 51% attack and do everything they want?</p>
</blockquote>

<p>In the case of isolated nodes, said ISP would still need enough hashing power to present blocks with sufficient PoW to be accepted (a LOT!) and, would have to also block <a href="https://bitcoin.stackexchange.com/questions/70069/how-can-i-setup-bitcoin-to-be-anonymous-with-tor">Tor</a>.</p>

CC BY-SA 3.0
2018-03-08T06:50:10.980Z
2018-03-08T06:50:10.980Z
Willtech
<p>I came to believe that an ISP can easily detect full nodes, BTC connections and isolate them from reaching any other nodes.</p>

<p>When and if an ISP decided to do so, could they easily perform a 51% attack and do everything they want?</p>

<nodes><attack><majority-attack>
What happens if an ISP isolates a portion of nodes?
qkhanhpro
# What happens if an ISP isolates a portion of nodes?

(Asked by: username_0 on 2018-02-05)

I came to believe that an ISP can easily detect full nodes, BTC connections and isolate them from reaching any other nodes.

When and if an ISP decided to do so, could they easily perform a 51% attack and do everything they want?

**Tags:** nodes, attack, majority-attack


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## 2 answers

### Answer by username_1 on 2018-02-05. Score: 1

Yes, but this would only work if said ISP would host more than 50% of all the full nodes in the network. This is simply not the case, the nodes in the network are too widely distributed for that.

> **Comments:**
> **username_0**: An ISP can isolate all TCP connection with the message signature corresponding to BTC protocol and completely control all the nodes under its host / letting only the nodes inside that ISP talk to eachother, is that right?  I mean, divide and conquer, not trying to attack the whole BTC network  

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### Answer by username_2 on 2018-03-08. Score: 0

> I came to believe that an ISP can easily detect full nodes, BTC connections and isolate them from reaching any other nodes.

This is true. An ISP could easily block all Bitcoin traffic or, just prevent Bitcoin traffic from entering/exiting their network and isolate the nodes.

> When and if an ISP decided to do so, they could easily perform a 51% attack and do everything they want?

In the case of isolated nodes, said ISP would still need enough hashing power to present blocks with sufficient PoW to be accepted (a LOT!) and, would have to also block [Tor](https://bitcoin.stackexchange.com/questions/70069/how-can-i-setup-bitcoin-to-be-anonymous-with-tor).


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