Ethereum: Why Bitcoin Does Not Respect RPCbind for Testnet

When it comes to running Ethereum, two of the most important tools are bitcoin.conf (the configuration file) and rpcbind (a daemon that provides remote access to the test network). However, we’ve noticed a peculiar issue with the rpcbind service on our test network, causing bitcoind (Ethereum’s command-line interface) to disregard changes made to the bitcoin.conf file.

In this article, we’ll delve into why this might be happening and explore possible solutions.

The Issue: Testnet RPC Configuration Disregard

When you’re testing Ethereum on your local machine or a virtual environment, you often need to configure rpcbind with specific settings, such as the port number for the test network (8333 in this case). However, when you make changes to the bitcoin.conf file, the changes are not reflected in the rpcbind configuration.

To illustrate this, let’s examine what happens if we edit the bitcoin.conf file:

Edit bitcoin.conf with a text editor

nano /etc/bitcoin.conf


[net]

httpHost = "127.0.0.1"

port = 8333


 rpcbind = "10.18.0.1:8332"

After making these changes, we can verify the updated configuration:

Check the rpcbind settings in bitcoin.conf

nano /etc/bitcoin.conf


[net]

httpHost = "127.0.0.1"

port = 8333


 rpcbind = "10.18.0.1:8332"

As expected, the rpcbind setting has been updated to reflect the changes we made in bitcoin.conf.

Why Does Bitcoin Not Respect RPC Configuration?

So, why doesn’t bitcoind respect these changes when updating bitcoin.conf? The issue lies with how netstat (the command-line interface for net and network configuration) handles remote connections.

When you run netstat -natp, it shows the listening TCP sockets. However, the rpcbind service is not actually a listening socket; it’s a daemon that runs in the background, monitoring incoming connections.

The rpcbind setting in bitcoin.conf refers to the address and port number for this daemon, which is currently set to listen on 10.18.0.1 (localhost). The issue arises because when we update the bitcoin.conf file, the rpcbind settings are not actually applied to the actual netstat process.

To fix this problem, you need to start rpcbind manually before updating your configuration files:

sudo systemctl start rpcbind

Additionally, make sure that bitcoind is configured to listen on a different address and port than the default 10.18.0.1. You can do this by modifying the bitcoin.conf file as follows:

[net]

httpHost = "127.0.0.1:8080"

port = 8333


 rpcbind = "10.0.0.2:8332" 
Change to a different address and port

After making these changes, you should be able to update your bitcoin.conf file without seeing any issues with the rpcbind settings.

In conclusion, this issue is due to how netstat handles remote connections, which can cause bitcoind to disregard updates made to its configuration files. By understanding what’s happening and taking a few simple steps to resolve the problem, you should be able to run Ethereum smoothly on your local machine or virtual environment.