Create you private Ethereum Network

This network would be using Clique (Proof of Authority) consensus protocol.

PreRequirements

• Hyperledger Besu
• Curl (or similar web service client).

1. Create directories

Each node requires a data directory for the blockchain data. When the node starts, Besu saves the node key in this directory.

Create directories for your private network, each of the three nodes, and a data directory for each node:

Clique-Network/
├── Node-1
│   ├── data
├── Node-2
│   ├── data
└── Node-3
    ├── data

2. Get the address for Node-1

In Clique networks, you must include the address of at least one initial signer in the genesis file. For this Clique network, we’ll use Node-1 as the initial signer. This requires obtaining the address for Node-1.

To get the address for Node-1, in the Node-1 directory, use the public-key export-address subcommand to write the node address to the specified file (node1Address in this example).

besu --data-path=data public-key export-address --to=data/node1Address

3. Create the genesis file

The genesis file defines the genesis block of the blockchain (that is, the start of the blockchain). The Clique genesis file includes the address of Node-1 as the initial signer in the extraData field.

All nodes in a network must use the same genesis file.

Copy the following genesis definition to a file called cliqueGenesis.json and save it in the Clique-Network directory:

{
  "config":{
    "chainId":1981,
    "constantinoplefixblock": 0,
    "clique":{
      "blockperiodseconds":15,
      "epochlength":30000
    }
  },
  "coinbase":"0x0000000000000000000000000000000000000000",
  "difficulty":"0x1",

"extraData":"0x0000000000000000000000000000000000000000000000000000000000000000<Node 1 Address>0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  "gasLimit":"0xa00000",
  "mixHash":"0x0000000000000000000000000000000000000000000000000000000000000000",
  "nonce":"0x0",
  "timestamp":"0x5c51a607",
  "alloc": {
      "fe3b557e8fb62b89f4916b721be55ceb828dbd73": {
        "privateKey": "8f2a55949038a9610f50fb23b5883af3b4ecb3c3bb792cbcefbd1542c692be63",
        "comment": "private key and this comment are ignored.  In a real chain, the private key should NOT be stored",
        "balance": "0xad78ebc5ac6200000"
      },
      "627306090abaB3A6e1400e9345bC60c78a8BEf57": {
        "privateKey": "c87509a1c067bbde78beb793e6fa76530b6382a4c0241e5e4a9ec0a0f44dc0d3",
        "comment": "private key and this comment are ignored.  In a real chain, the private key should NOT be stored",
        "balance": "90000000000000000000000"
      },
      "f17f52151EbEF6C7334FAD080c5704D77216b732": {
        "privateKey": "ae6ae8e5ccbfb04590405997ee2d52d2b330726137b875053c36d94e974d162f",
        "comment": "private key and this comment are ignored.  In a real chain, the private key should NOT be stored",
        "balance": "90000000000000000000000"
      }
   },
  "number":"0x0",
  "gasUsed":"0x0",
  "parentHash":"0x0000000000000000000000000000000000000000000000000000000000000000"
}

In extraData, replace <Node 1 Address> with the address for Node-1, excluding the 0x prefix.

4. Start the first node as the bootnode

Start Node-1:

besu --data-path=data --genesis-file=../cliqueGenesis.json --network-id 123 --rpc-http-enabled --rpc-http-api=ETH,NET,CLIQUE --host-allowlist="*" --rpc-http-cors-origins="all"

The command line enables:

• The JSON-RPC API using the --rpc-http-enabled option
• The ETH, NET, and CLIQUE APIs using the --rpc-http-api option
• All-host access to the HTTP JSON-RPC API using the --host-allowlist option
• All-domain access to the node through the HTTP JSON-RPC API using the --rpc-http-cors-origins option.

When the node starts, the enode URL displays.

5. Start Node-2

Start another terminal, change to the Node-2 directory and start Node-2 specifying the Node-1 enode URL copied when starting Node-1 as the bootnode:

besu --data-path=data --genesis-file=../cliqueGenesis.json --bootnodes=<Node-1 Enode URL> --network-id 123 --p2p-port=30304 --rpc-http-enabled --rpc-http-api=ETH,NET,CLIQUE --host-allowlist="*" --rpc-http-cors-origins="all" --rpc-http-port=8546

The command line specifies:

• A Different port to Node-1 for P2P peer discovery using the --p2p-port option.
• A Different port to Node-1 for HTTP JSON-RPC using the --rpc-http-port option.
• The enode URL for Node-1 using the --bootnodes option.
• The data directory for Node-2 using the --data-path option.
• Other options as for Node-1.

6. Start Node-3

Start another terminal, change to the Node-3 directory and start Node-3 specifying the Node-1 enode URL copied when starting Node-1 as the bootnode:

besu --data-path=data --genesis-file=../cliqueGenesis.json --bootnodes=<Node-1 Enode URL> --network-id 123 --p2p-port=30305 --rpc-http-enabled --rpc-http-api=ETH,NET,CLIQUE --host-allowlist="*" --rpc-http-cors-origins="all" --rpc-http-port=8547

The command line specifies:

• A different port to Node-1 and Node-2 for P2P peer discovery using the --p2p-port option.
• A different port to Node-1 and Node-2 for HTTP JSON-RPC using the --rpc-http-port option.
• The data directory for Node-3 using the --data-path option.
• The bootnode as for Node-2
• Other options as for Node-1.

7. Confirm the private network is working

Start another terminal, use curl to call the JSON-RPC API net_peerCount method and confirm the nodes are functioning as peers:

curl -X POST --data '{"jsonrpc":"2.0","method":"net_peerCount","params":[],"id":1}' localhost:8545

The result confirms Node-1 has two peers (Node-2 and Node-3):

{
  "jsonrpc" : "2.0",
  "id" : 1,
  "result" : "0x2"
}

Stop the nodes

When finished using the private network, stop all nodes using Ctrl+C in each terminal window.