Setting Up a Private Ethereum Blockchain

Tutorial Overview

This tutorial guides you through creating a private Ethereum blockchain on Windows. You will install the required tools, create a genesis block, initialize a local chain, start a private network, create accounts and mine development Ether.

Prerequisites Overview

Before setting up your private Ethereum blockchain, prepare the following components.

Installing Node.js and Development Tools

Option 1: Direct Download

Download Node.js directly from the official Node.js website.

Option 2: Using Chocolatey

Run PowerShell as Administrator and execute these commands.

Set-ExecutionPolicy Bypass

iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))

choco install visualstudiocode -y
choco install git -y
choco install nodejs -y

Wallet Tools

The original tutorial uses Ethereum Mist Wallet. For modern learning, you may use a current wallet such as MetaMask to interact with a private network. If you are following the original Windows 10 steps exactly, you can keep the legacy wallet section as a historical reference.

Legacy Ethereum Wallet Setup

1. Download the Ethereum Wallet release package.
2. Create the folder C:\Program Files\Ethereum.
3. Extract the wallet files to the folder.

Installing Geth

What is Geth?

Geth stands for Go Ethereum. It is the Ethereum client used in this tutorial to run the node, initialize the chain, open the console and mine blocks on your private network.

Installation Steps

1. Download and install Geth for Windows.
2. Use the default installation folder unless you have a specific reason to change it.
3. Confirm the expected installation path.

C:\Program Files\Geth

Setting Up Environment Variables

Why Set PATH Variables?

Adding tools to your system PATH allows you to run commands from any command prompt location.

Steps to Configure

1. Right-click This PC and choose Properties.
2. Click Advanced system settings.
3. Click Environment Variables.
4. Select Path under System Variables.
5. Click Edit and add the required folders.

C:\Program Files\Ethereum-Wallet
C:\Program Files\Geth

Understanding the Genesis Block

What is a Genesis Block?

The genesis block is the first block in a blockchain network. It acts as the foundation for all later blocks and defines the starting rules of the private network.

What You Configure

• Network ID and chain configuration.
• Mining difficulty and gas limits.
• Initial account allocations.
• Consensus and block parameters.

Genesis Block Parameters Explained

Creating the Genesis Block

Step 1: Create the JSON File

Create a file named myGenesis.json.

{
  "config": {
    "chainId": 45,
    "homesteadBlock": 0,
    "eip155Block": 0,
    "eip158Block": 0,
    "byzantiumBlock": 12
  },
  "alloc": {},
  "coinbase": "0x0000000000000000000000000000000000000000",
  "difficulty": "0x20000",
  "extraData": "",
  "gasLimit": "0x2fefd8",
  "nonce": "0x0000000000000042",
  "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "timestamp": "0x00"
}

Step 2: Save the File

Save myGenesis.json in the same working folder you will use for Geth.

Initialize the Genesis Block

Run the Initialization Command

geth init myGenesis.json

What Happens

• Geth reads the genesis configuration.
• It creates the blockchain database.
• It sets up the initial network parameters.
• It creates the Ethereum folder structure.

C:\Users\[username]\AppData\Roaming\Ethereum

Starting Your Private Network

Launch the Network

geth --networkid=5 console

Command Breakdown

• geth: Runs the Go Ethereum client.
• --networkid=5: Sets a private network ID.
• console: Opens the interactive JavaScript console.

Launch Wallet Interface

1. Start the wallet application or connect a modern wallet to your private network.
2. Make sure Geth is still running in the background.
3. Confirm the wallet shows the private network and starts from the genesis block.

Creating Your First Account

Method 1: Using Wallet Interface

1. Open your wallet tool.
2. Navigate to the account or wallet section.
3. Create a new account.
4. Set a strong password and keep it safely.

Method 2: Using Geth Console

geth account new

What You Get

• Account address: Unique Ethereum-style address.
• Private key: Stored encrypted in your keystore.
• Initial balance: Zero ETH until you mine or allocate funds.

Mining Your First Blocks

Start the Mining Process

miner.start(1)

What This Command Does

• miner.start() begins mining.
• 1 uses one CPU thread.
• New blocks are created on the private network.
• Mining rewards are assigned to the coinbase account.

Monitor Your Progress

• Watch the console for mining messages.
• Check whether the wallet balance increases.
• Observe the block number increasing.

Stop Mining

miner.stop()

You may also press Ctrl + C in the console when appropriate.

Conclusion and Next Steps

What You Have Accomplished

What to Explore Next

• Deploy smart contracts to your private network.
• Create multiple accounts and transfer Ether.
• Experiment with different network and mining parameters.
• Connect multiple nodes to form a private network.
• Build and test DApps on your private chain.

Development Flow