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Creating a Private Network using IBFT 2.0 (Proof of Authority) Consensus Protocol

A private network provides a configurable network for testing. This private network uses the IBFT 2.0 (Proof of Authority) consensus protocol.

Important

An Ethereum private network created as described here is isolated but not protected or secure. We recommend running the private network behind a properly configured firewall.

Prerequisites

Pantheon

Curl (or similar web service client)

Steps

To create a private network using IBFT 2.0 with three nodes and one initial validator:

  1. Create Folders
  2. Get Public Key for Node-1
  3. Get Node Addresses
  4. Create JSON File to RLP Encode
  5. RLP Encode Extra Data
  6. Create Genesis File
  7. Delete Database Directory
  8. Start First Node as Bootnode
  9. Start Node-2
  10. Start Node-3
  11. Confirm Private Network is Working

1. Create Folders

Each node requires a data directory for the blockchain data. When the node is started, the node key is saved in this directory.

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

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

2. Get Public Key for Node-1

The public key of Node-1 is needed for the enode URL. The enode URL is used when starting Node-2 and Node-3 to specify Node-1 is the bootnode.

In the Node-1 directory, use the public-key export subcommand to write the node public key to the specified file (publicKey):

pantheon --data-path=data public-key export --to=data/publicKey
pantheon --data-path=path public-key export --to=data\publicKey

Your node 1 directory now contains:

├── Node-1
    ├── data
        ├── database
        ├── key
        ├── publicKey

The database directory contains the blockchain data.

3. Get Node Addresses

In IBFT 2.0 networks, the address of at least one initial validator must be included in the genesis file in the RLP encoded extraData string. For this network, we will use Node-1 as the initial validator. This requires obtaining the address for Node-1.

To obtain 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 (nodeAddress)

pantheon --data-path=data public-key export-address --to=data/nodeAddress
pantheon --data-path=data public-key export-address --to=data\nodeAddress

To vote in validators once the network is running, the node address for the proposed validator is required. In the Node-2 and Node-3 directories, write the node address for each node to the specified file using the public-key export-address command as for Node-1.

4. Create JSON File to RLP Encode

Create a file called toEncode.json in the IBFT-Network directory that contains the Node 1 address excluding the 0x prefix from the nodeAddress file in the Node-1/data directory:

[
 "<Node 1 Address>"
]
[
 "9b9f91039843450927b0043ae71cd803e0db0c30"
]

5. RLP Encode Extra Data

The extraData property in IBFT 2.0 genesis files is an RLP encoding of [32 Bytes Vanity, List<Validators>, No Vote, Round=Int(0), 0 Seals].

In the IBFT-Network directory, use the Pantheon subcommand rlp encode to generate the extraData RLP string to include in the genesis file.

pantheon rlp encode --from=toEncode.json --to=rlpEncodedExtraData
pantheon rlp encode --from=toEncode.json --to=rlpEncodedExtraData

6. Create Genesis File

The genesis file defines the genesis block of the blockchain (that is, the start of the blockchain). The IBFT 2.0 genesis file includes the address of Node-1 as the initial validator in the RLP encoded extraData string.

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

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

{
  "config": {
    "chainId": 1981,
    "constantinoplefixblock": 0,
    "ibft2": {
      "blockperiodseconds": 2,
      "epochlength": 30000,
      "requesttimeoutseconds": 10
    }
  },
  "nonce": "0x0",
  "timestamp": "0x58ee40ba",
  "extraData": "<RLP Encoded Extra Data>",
  "gasLimit": "0x47b760",
  "difficulty": "0x1",
  "mixHash": "0x63746963616c2062797a616e74696e65206661756c7420746f6c6572616e6365",
  "coinbase": "0x0000000000000000000000000000000000000000",
  "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"
      }
   }
}

In extraData, copy the RLP encoded data from the rlpEncodedExtraData file.

Example

{
  ...
"extraData":0xf83ea00000000000000000000000000000000000000000000000000000000000000000d5949b9f91039843450927b0043ae71cd803e0db0c30808400000000c0",
  ...
}

Warning

Do not use the accounts in alloc in the genesis file on mainnet or any public network except for testing.

The private keys are displayed which means the accounts are not secure.

7. Delete Database Directories

Delete the database directories created when getting the public key for Node-1 and addresses for Node-2 and Node-3. The nodes cannot be started with the IBFT 2.0 genesis file while the previously generated data is in the database directories.

8. Start First Node as Bootnode

In the Node-1 directory, start Node-1:

pantheon --data-path=data --genesis-file=../ibftGenesis.json --rpc-http-enabled --rpc-http-api=ETH,NET,IBFT --host-whitelist=* --rpc-http-cors-origins="all"      
pantheon --data-path=data --genesis-file=..\ibftGenesis.json --rpc-http-enabled --rpc-http-api=ETH,NET,IBFT --host-whitelist=* --rpc-http-cors-origins="all"    

The command line specifies:

9. Start Node-2

You need the enode URL for Node-1 to specify Node-1 as a bootnode.

Start another terminal, change to the Node-2 directory and start Node-2 replacing the enode URL with your bootonde:

pantheon --data-path=data --genesis-file=../ibftGenesis.json --bootnodes="enode://<node public key ex 0x>@127.0.0.1:30303" --p2p-port=30304 --rpc-http-enabled --rpc-http-api=ETH,NET,IBFT --host-whitelist=* --rpc-http-cors-origins="all" --rpc-http-port=8546     
pantheon --data-path=data --genesis-file=..\ibftGenesis.json --bootnodes="enode://<node public key ex 0x>@127.0.0.1:30303" --p2p-port=30304 --rpc-http-enabled --rpc-http-api=ETH,NET,IBFT --host-whitelist=* --rpc-http-cors-origins="all" --rpc-http-port=8546     

The command line specifies:

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

10. Start Node-3

Start another terminal, change to the Node-3 directory and start Node-3 replacing the enode URL with your bootnode:

pantheon --data-path=data --genesis-file=../ibftGenesis.json --bootnodes="enode://<node public key ex 0x>@127.0.0.1:30303" --p2p-port=30305 --rpc-http-enabled --rpc-http-api=ETH,NET,IBFT --host-whitelist=* --rpc-http-cors-origins="all" --rpc-http-port=8547    
pantheon --data-path=data --genesis-file=..\ibftGenesis.json --bootnodes="enode://<node public key ex 0x>@127.0.0.1:30303" --p2p-port=30305 --rpc-http-enabled --rpc-http-api=ETH,NET,IBFT --host-whitelist=* --rpc-http-cors-origins="all" --rpc-http-port=8547    

The command line specifies:

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

11. Confirm 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}' 127.0.0.1:8545

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

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

Next Steps

Look at the logs displayed to confirm Node-1 is producing blocks and Node-2 and Node-3 are importing blocks.

Use the IBFT API to add Node-2 or Node-3 as a validator.

Note

To add Node-2 or Node-3 as a validator you need the node address as when specifying Node-1 as the initial validator.

Import accounts to MetaMask and send transactions as described in the Private Network Quickstart Tutorial

Info

Pantheon does not implement private key management.

Stop Nodes

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

Tip

To restart the IBFT 2.0 network in the future, start from 8. Start First Node as Bootnode.

Questions or feedback? You can discuss issues and obtain free support on Pegasys Pantheon Gitter room.
For paid professional support by PegaSys, contact us at [email protected]