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.
- 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
-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?