<p>Nodes that participate in the Bitcoin network run a computer program such as this one: <a href="https://github.com/bitcoin/bitcoin" rel="nofollow noreferrer">https://github.com/bitcoin/bitcoin</a>, which dictates how everything works.</p>

<p>To answer your more specific questions:</p>

<ul>
<li><p>Yes, bitcoin once used UPnP, here are some more details: <a href="https://dirkmittler.homeip.net/blog/archives/3340" rel="nofollow noreferrer">https://dirkmittler.homeip.net/blog/archives/3340</a> but in modern versions it does not (thanks for specifying this the comment section). </p></li>
<li><p>Bitcoin uses TCP, and hole punching over it is not reliable.. Here's another place where this is briefly touched upon <a href="https://bitcoin.stackexchange.com/questions/43355/can-exist-bitcoin-network-with-all-nodes-behind-nat">Can exist bitcoin network with all nodes behind NAT?</a></p></li>
</ul>

CC BY-SA 4.0
2019-09-29T19:18:28.057Z
No modern versions include UPnP.
Claris
CC BY-SA 4.0
2019-09-29T16:43:42.903Z
2019-09-29T19:30:30.120Z
2019-09-29T19:30:30.120Z
bitfede
<p>But does every peer node in the bitcoin p2p network need to have ports forwarded in order to participate? Otherwise, how does the p2p network work in the Bitcoin network?</p>

<p>I heard that there are some technologies for implementing peer-to-peer networks such as UPnP and Hole Punching, does Bitcoin use any of these technologies for its p2p network?</p>

CC BY-SA 4.0
2019-09-29T16:39:18.560Z
Possible duplicate of [What is the NAT traversal technique used by bitcoin](https://bitcoin.stackexchange.com/questions/61546/what-is-the-nat-traversal-technique-used-by-bitcoin)
RedGrittyBrick
<network><connection><peer-discovery><port><p2p>
How does the Bitcoin p2p network work? Does it need port forwarding?
DanielSeow
# How does the Bitcoin p2p network work? Does it need port forwarding?

(Asked by: username_0 on 2019-09-29)

But does every peer node in the bitcoin p2p network need to have ports forwarded in order to participate? Otherwise, how does the p2p network work in the Bitcoin network?

I heard that there are some technologies for implementing peer-to-peer networks such as UPnP and Hole Punching, does Bitcoin use any of these technologies for its p2p network?

**Tags:** network, connection, peer-discovery, port, p2p

> **Comments:**
> **username_1**: Possible duplicate of [What is the NAT traversal technique used by bitcoin](https://bitcoin.stackexchange.com/questions/61546/what-is-the-nat-traversal-technique-used-by-bitcoin)  

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## 1 answers

### Answer by username_2 on 2019-09-29. Score: 2

Nodes that participate in the Bitcoin network run a computer program such as this one: <https://github.com/bitcoin/bitcoin>, which dictates how everything works.

To answer your more specific questions:

* Yes, bitcoin once used UPnP, here are some more details: <https://dirkmittler.homeip.net/blog/archives/3340> but in modern versions it does not (thanks for specifying this the comment section).
* Bitcoin uses TCP, and hole punching over it is not reliable.. Here's another place where this is briefly touched upon [Can exist bitcoin network with all nodes behind NAT?](https://bitcoin.stackexchange.com/questions/43355/can-exist-bitcoin-network-with-all-nodes-behind-nat)

> **Comments:**
> **username_3**: No modern versions include UPnP.  

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