<blockquote>
<p><strong>I read some article and they said on the internet, computers are connected through hub(s)</strong>.</p>
</blockquote>
<p>That article is wrong, outdated or using the word hub in an excessively casual way.</p>
<p>Hubs were devices that connected computers together in older Ethernet networks (10-Base-T and older IIRC). Later Ethernet networks use devices named switches.</p>
<p>There is a model for the Internet, known as the Internet 4-layer model (which is different from the obsolete ISO 7-layer model used for X25 etc). Each layer adds capabilities on top of lower layers. The layers are (bottom to top): physical, network, inter-network and application.</p>
<pre><code>Application layer
Internetwork layer
Network Layer
Physical Layer
</code></pre>
<hr />
<p>Bitcoin is an application layer protocol. When we say that one Bitcoin node communicates directly with another node (peer to peer) we are only talking about the view of the application layer. Underneath this, at the network layer the data packets pass through intermediary devices such as switches (or hubs in prior millenia). At the inter-network layer the packets also pass through routers.</p>
<p>The Bitcoin network protocol is a so-called gossip protocol. Each node only communicates with a very small number neighbours (peer nodes). Nodes pass on messages they receive. Eventually a message will have been copied to every node in the network.</p>
<hr />
<p>To send a message to a peer node named red.example.com a Bitcoin node application (in the Application Layer) constructs a Bitcoin message and passes it down to the internetwork layer on the same computer.</p>
<p>That internetwork layer looks up the name red.example.com to find it's Internet protocol (IP) address 1.2.3.4 using a Domain Name Service (DNS). The internetwork layer notices that 1.2.3.4 is not a local address and must be passed through a router. The internetwork layer also uses routing protocol messages (including <a href="https://superuser.com/a/528010/52492">ICMP redirections</a>) to decide which router to be used. The internetwork layer adds the IP address header to the message and passes the message down to the network layer on the same computer.</p>
<p>The network layer is often Ethernet based. In this case the network layer first asks the physical layer to send out an Address Resolution Protocol message (ARP) to the ethernet broadcast address. The ARP message asks any recipients who use the target IP-address to respond with their ethernet address (also called a Media Access Control (MAC) address). After receiving a reply, the network layer can add the ethernet header to the message and ask the physical layer to send the message to the router to be forwarded towards 1.2.3.4 over however many hops (between routers) are required along whatever route each router feels is currently available and most optimal.</p>
<p>The hardware layer will transmit the message down a wire. This wire typically connects to a network switch which retransmits the message along another wire based on knowledge it has accumulated about which ethernet addresses are associated with each of the many wires connected to the switch.</p>
<p>So yes, there is a lot of infrastructure between any two Bitcoin nodes and all Bitcoin nodes are ultimately involved in passing your Bitcoin messages around. However there are multiple ways (routes if you like) that a Bitcoin message reaches another specific node - so it doesn't matter if a few hostile, passive or broken nodes don't pass on your message.</p>
<hr />
<blockquote>
<p><strong>Is it ok to assume that the only thing that can be a 'betrayer' is hub?</strong></p>
</blockquote>
<p>No. Data passes through lots of things between two bitcoin nodes. Most of these are owned, configured and run by other people, some of whom may potentially be hostile.</p>
<hr />
<blockquote>
<p><strong>why should we be bothered with other users while broadcasting?</strong></p>
</blockquote>
<p>If by &quot;bothered with&quot; you mean worried about, the software you use for financial transactions needs to be able to operate safely in an environment that contains hostile parties. A hostile intermediary might conduct an attack such as an eclipse attack, designed to do you financial harm. I doubt most Bitcoin users need spend much time worrying about this on a daily basis but I guess it would be wise to at least be aware of these issues when selecting, configuring and using software.</p>
<p>If by &quot;bothered with&quot; you mean collaborate with / support, you and your Bitcoin application don't need to interact with owners of these intermediary devices other than typically by paying your Internet Service Provider (ISP) their monthly fee</p>

CC BY-SA 4.0
2022-09-22T02:46:33.617Z
Thanks! So you mean at network layer level data don't have to be transfered node by node and routers or switches 'can' be the only intermediaries, but using bitcoin-an application layer level  protocol-transaction signals are intentionally guided to intermediate nodes which are branches of a direct(including some routers etc though) connecting line between two nodes for some reason?
resibit72
CC BY-SA 4.0
2022-09-22T16:44:08.777Z
I think you have it right, maybe I'll update the answer to try and make this clearer.
RedGrittyBrick
CC BY-SA 4.0
2022-09-21T23:12:29.160Z
2022-09-22T17:21:48.590Z
2022-09-22T17:21:48.590Z
RedGrittyBrick
<p>Context here: I'm a newbie on internet&amp;blockchain, but I read some article and they said on the internet, computers are connected through hub(s).</p>
<p>So, It seems to me that there's no other 'users' between me and other users(hub is not user I guess?). Then, is it ok to assume that the only thing that can be a 'betrayer' is hub? why should we be bothered with other users while broadcasting? I'm confused. help me please.</p>

CC BY-SA 4.0
2022-09-21T12:59:14.617Z
You're going to explain your terminology, or provide a reference where you learned about this terms. What is a "hub"? What is a "betrayer"? What is a "user"? What context are you talking about?
Pieter Wuille
CC BY-SA 4.0
2022-09-21T13:30:09.767Z
Oh, I'm sorry. Hub is an equipment or system that allows several computers to be connected with each other. Betrayer is a node that will deceive other nodes when they relay data. User is a real person or computer that is controlled by them.
resibit72
CC BY-SA 4.0
2022-09-21T13:30:29.070Z
Ok, so what does that have to do with Bitcoin?
Pieter Wuille
CC BY-SA 4.0
2022-09-21T13:51:00.727Z
I thought if every node is connected with each other directly, then broadcasting is enough to prevent hacking because there can't be BGP. And I think it's almost the same situation where the only intermidiary between nodes is a hub, which is as far as I know a general method to connect computers on the internet now. So I wonder why BGP was considered a core problem in Bitcoin
resibit72
<blockchain>
are the hubs on the internet the only hackable 'computer'?
resibit72
# are the hubs on the internet the only hackable 'computer'?

(Asked by: username_0 on 2022-09-21)

Context here: I'm a newbie on internet&blockchain, but I read some article and they said on the internet, computers are connected through hub(s).

So, It seems to me that there's no other 'users' between me and other users(hub is not user I guess?). Then, is it ok to assume that the only thing that can be a 'betrayer' is hub? why should we be bothered with other users while broadcasting? I'm confused. help me please.

**Tags:** blockchain

> **Comments:**
> **username_1**: You're going to explain your terminology, or provide a reference where you learned about this terms. What is a "hub"? What is a "betrayer"? What is a "user"? What context are you talking about?  
> **username_0**: Oh, I'm sorry. Hub is an equipment or system that allows several computers to be connected with each other. Betrayer is a node that will deceive other nodes when they relay data. User is a real person or computer that is controlled by them.  
> **username_1**: Ok, so what does that have to do with Bitcoin?  
> **username_0**: I thought if every node is connected with each other directly, then broadcasting is enough to prevent hacking because there can't be BGP. And I think it's almost the same situation where the only intermidiary between nodes is a hub, which is as far as I know a general method to connect computers on the internet now. So I wonder why BGP was considered a core problem in Bitcoin  

---

## 1 answers

### Answer by username_2 on 2022-09-21. Score: 1

> **I read some article and they said on the internet, computers are connected through hub(s)**.

That article is wrong, outdated or using the word hub in an excessively casual way.

Hubs were devices that connected computers together in older Ethernet networks (10-Base-T and older IIRC). Later Ethernet networks use devices named switches.

There is a model for the Internet, known as the Internet 4-layer model (which is different from the obsolete ISO 7-layer model used for X25 etc). Each layer adds capabilities on top of lower layers. The layers are (bottom to top): physical, network, inter-network and application.

```
Application layer
Internetwork layer
Network Layer
Physical Layer

```

---

Bitcoin is an application layer protocol. When we say that one Bitcoin node communicates directly with another node (peer to peer) we are only talking about the view of the application layer. Underneath this, at the network layer the data packets pass through intermediary devices such as switches (or hubs in prior millenia). At the inter-network layer the packets also pass through routers.

The Bitcoin network protocol is a so-called gossip protocol. Each node only communicates with a very small number neighbours (peer nodes). Nodes pass on messages they receive. Eventually a message will have been copied to every node in the network.

---

To send a message to a peer node named red.example.com a Bitcoin node application (in the Application Layer) constructs a Bitcoin message and passes it down to the internetwork layer on the same computer.

That internetwork layer looks up the name red.example.com to find it's Internet protocol (IP) address 1.2.3.4 using a Domain Name Service (DNS). The internetwork layer notices that 1.2.3.4 is not a local address and must be passed through a router. The internetwork layer also uses routing protocol messages (including [ICMP redirections](https://superuser.com/a/528010/52492)) to decide which router to be used. The internetwork layer adds the IP address header to the message and passes the message down to the network layer on the same computer.

The network layer is often Ethernet based. In this case the network layer first asks the physical layer to send out an Address Resolution Protocol message (ARP) to the ethernet broadcast address. The ARP message asks any recipients who use the target IP-address to respond with their ethernet address (also called a Media Access Control (MAC) address). After receiving a reply, the network layer can add the ethernet header to the message and ask the physical layer to send the message to the router to be forwarded towards 1.2.3.4 over however many hops (between routers) are required along whatever route each router feels is currently available and most optimal.

The hardware layer will transmit the message down a wire. This wire typically connects to a network switch which retransmits the message along another wire based on knowledge it has accumulated about which ethernet addresses are associated with each of the many wires connected to the switch.

So yes, there is a lot of infrastructure between any two Bitcoin nodes and all Bitcoin nodes are ultimately involved in passing your Bitcoin messages around. However there are multiple ways (routes if you like) that a Bitcoin message reaches another specific node - so it doesn't matter if a few hostile, passive or broken nodes don't pass on your message.

---

> **Is it ok to assume that the only thing that can be a 'betrayer' is hub?**

No. Data passes through lots of things between two bitcoin nodes. Most of these are owned, configured and run by other people, some of whom may potentially be hostile.

---

> **why should we be bothered with other users while broadcasting?**

If by "bothered with" you mean worried about, the software you use for financial transactions needs to be able to operate safely in an environment that contains hostile parties. A hostile intermediary might conduct an attack such as an eclipse attack, designed to do you financial harm. I doubt most Bitcoin users need spend much time worrying about this on a daily basis but I guess it would be wise to at least be aware of these issues when selecting, configuring and using software.

If by "bothered with" you mean collaborate with / support, you and your Bitcoin application don't need to interact with owners of these intermediary devices other than typically by paying your Internet Service Provider (ISP) their monthly fee

> **Comments:**
> **username_0**: Thanks! So you mean at network layer level data don't have to be transfered node by node and routers or switches 'can' be the only intermediaries, but using bitcoin-an application layer level  protocol-transaction signals are intentionally guided to intermediate nodes which are branches of a direct(including some routers etc though) connecting line between two nodes for some reason?  
> **username_2**: I think you have it right, maybe I'll update the answer to try and make this clearer.  

---

