<p>It is used for incoming Tor connections.</p>
<p>See <a href="https://github.com/bitcoin/bitcoin/blob/6ef84e0503994c53f77093e7ea5951a7b0edea7a/doc/tor.md" rel="noreferrer">here</a> and <a href="https://github.com/bitcoin/bitcoin/blob/623745ca74cf3f54b474dac106f5802b7929503f/src/chainparamsbase.cpp#L40" rel="noreferrer">here</a> for more info.</p>
<p>You can use <code>-bind=127.0.0.1:XXXX=onion</code> to use port <code>XXXX</code> instead.</p>

CC BY-SA 4.0
2022-01-03T22:50:41.700Z
2022-01-04T01:16:37.513Z
2022-01-04T01:16:37.513Z
meshcollider
<p>Bitcoin Core listens on three ports, as can be seen by running the following command after it has started:</p>
<blockquote>
<p><code>sudo netstat -tulpn | grep LISTEN</code></p>
</blockquote>
<p>By default, the ports it listens on are:</p>
<ul>
<li>8332 for the RPC client (i.e. <code>bitcoin-cli</code>)</li>
<li>8333 for bitcoin clients (other nodes who want to contact this node)</li>
<li>8334 for ????</li>
</ul>
<p>Searching for information on port 8334 does not seem to turn up anything useful.</p>
<p>By observation, if the port is already bound to, it does not cause a fatal error. Bitcoin Core continues to start, although the <code>debug.log</code> shows the following:</p>
<blockquote>
<p><code>Unable to bind to 127.0.0.1:8334 on this computer. Bitcoin Core is probably already running.</code></p>
</blockquote>
<p>What does Bitcoin Core use port 8334 for?</p>
<p>Furthermore, other ports can be overridden using command-line arguments such as <code>-rpcport=18332</code> and <code>-port=18333</code> or similar configuration options in <code>bitcoin.conf</code>. How can Bitcoin Core be made to listen on a different port number than 8334 for whatever it uses that port for?</p>

<bitcoin-core><port>
What does Bitcoin Core use port 8334 for?
Robert Dickinson
# What does Bitcoin Core use port 8334 for?

(Asked by: username_0 on 2022-01-03)

Bitcoin Core listens on three ports, as can be seen by running the following command after it has started:

> `sudo netstat -tulpn | grep LISTEN`

By default, the ports it listens on are:

* 8332 for the RPC client (i.e. `bitcoin-cli`)
* 8333 for bitcoin clients (other nodes who want to contact this node)
* 8334 for ????

Searching for information on port 8334 does not seem to turn up anything useful.

By observation, if the port is already bound to, it does not cause a fatal error. Bitcoin Core continues to start, although the `debug.log` shows the following:

> `Unable to bind to 127.0.0.1:8334 on this computer. Bitcoin Core is probably already running.`

What does Bitcoin Core use port 8334 for?

Furthermore, other ports can be overridden using command-line arguments such as `-rpcport=18332` and `-port=18333` or similar configuration options in `bitcoin.conf`. How can Bitcoin Core be made to listen on a different port number than 8334 for whatever it uses that port for?

**Tags:** bitcoin-core, port


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## 1 answers

### Answer by username_1 on 2022-01-03. Score: 11 | Accepted answer

It is used for incoming Tor connections.

See [here](https://github.com/bitcoin/bitcoin/blob/6ef84e0503994c53f77093e7ea5951a7b0edea7a/doc/tor.md) and [here](https://github.com/bitcoin/bitcoin/blob/623745ca74cf3f54b474dac106f5802b7929503f/src/chainparamsbase.cpp#L40) for more info.

You can use `-bind=127.0.0.1:XXXX=onion` to use port `XXXX` instead.


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