# Creating a Private Network using Ethash (Proof of Work) Consensus Protocol

A private network provides a configurable network for testing. By configuring a low difficulty and enabling 
mining, blocks are created quickly. 

You can test multi-block and multi-user scenarios on a private network before moving to one of the public testnets. 

!!!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](../Installation/Install-Binaries.md) 

[Curl (or similar web service client)](https://curl.haxx.se/download.html) 

## Steps

To create a private network: 

1. [Create Folders](#1-create-folders)
1. [Create Genesis File](#2-create-genesis-file)
1. [Start First Node as Bootnode](#3-start-first-node-as-bootnode)
1. [Start Node-2](#4-start-node-2)
1. [Start Node-3](#5-start-node-3)
1. [Confirm Private Network is Working](#6-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: 

```bash
Private-Network/
├── Node-1
│   ├── data
├── Node-2
│   ├── data
└── Node-3
    ├── data
```

### 2. Create Genesis File 

The genesis file defines the genesis block of the blockchain (that is, the start of the blockchain).
The genesis file includes entries for configuring the blockchain such as the mining difficulty and initial 
accounts and balances.    

All nodes in a network must use the same genesis file. The [network ID](../Configuring-Pantheon/NetworkID-And-ChainID.md) 
defaults to the `chainID` in the genesis file. The `fixeddifficulty` enables blocks to be mined quickly.   

Copy the following genesis definition to a file called `privateNetworkGenesis.json` and save it in the `Private-Network` directory: 

```json
{
  "config": {
      "constantinoplefixblock": 0,
      "ethash": {
        "fixeddifficulty": 1000
      },
       "chainID": 1981
   },
  "nonce": "0x42",
  "gasLimit": "0x1000000",
  "difficulty": "0x10000",
  "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"
    },
    "f17f52151EbEF6C7334FAD080c5704D77216b732": {
      "privateKey": "ae6ae8e5ccbfb04590405997ee2d52d2b330726137b875053c36d94e974d162f",
      "comment": "private key and this comment are ignored.  In a real chain, the private key should NOT be stored",
      "balance": "90000000000000000000000"
    }
  }
}
```

!!! warning
    Do not use the accounts in the genesis file above on mainnet or any public network except for testing.
    The private keys are displayed so the accounts are not secure. 
   
### 3. Start First Node as Bootnode 

Start Node-1:

```bash tab="MacOS"
pantheon --data-path=data --genesis-file=../privateNetworkGenesis.json --bootnodes --miner-enabled --miner-coinbase fe3b557e8fb62b89f4916b721be55ceb828dbd73 --rpc-http-enabled --host-whitelist=* --rpc-http-cors-origins="all"     
```

```bash tab="Windows"
pantheon --data-path=data --genesis-file=..\privateNetworkGenesis.json --bootnodes --miner-enabled --miner-coinbase fe3b557e8fb62b89f4916b721be55ceb828dbd73 --rpc-http-enabled --host-whitelist=* --rpc-http-cors-origins="all"    
```

The command line specifies: 

* No arguments for the [`--bootnodes`](../Reference/Pantheon-CLI-Syntax.md#bootnodes) option because this is your bootnode.
* Mining is enabled and the account to which mining rewards are paid using the [`--miner-enabled`](../Reference/Pantheon-CLI-Syntax.md#miner-enabled) 
and [`--miner-coinbase`](../Reference/Pantheon-CLI-Syntax.md#miner-coinbase) options.
* JSON-RPC API is enabled using the [`--rpc-http-enabled`](../Reference/Pantheon-CLI-Syntax.md#rpc-http-enabled) option.
* All hosts can access the HTTP JSON-RPC API using the [`--host-whitelist`](../Reference/Pantheon-CLI-Syntax.md#host-whitelist) option.
* All domains can access the node using the HTTP JSON-RPC API using the [`--rpc-http-cors-origins`](../Reference/Pantheon-CLI-Syntax.md#rpc-http-cors-origins) option.  

!!! info
    The miner coinbase account is one of the accounts defined in the genesis file. 

When the node starts, the [enode URL](../Configuring-Pantheon/Node-Keys.md#enode-url) is displayed.
Copy the enode URL to specify Node-1 as the bootnode in the following steps. 

![Node 1 Enode URL](../images/EnodeStartup.png)

### 4. 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:

```bash tab="MacOS"
pantheon --data-path=data --genesis-file=../privateNetworkGenesis.json --bootnodes=<Node-1 Enode URL> --p2p-port=30304      
```

```bash tab="Windows"
pantheon --data-path=data --genesis-file=..\privateNetworkGenesis.json --bootnodes=<Node-1 Enode URL> --p2p-port=30304      
```

The command line specifies: 

* Different port to Node-1 for P2P peer discovery using the [`--p2p-port`](../Reference/Pantheon-CLI-Syntax.md#p2p-port) option.
* Enode URL for Node-1 using the [`--bootnodes`](../Reference/Pantheon-CLI-Syntax.md#bootnodes) option.
* Data directory for Node-2 using the [`--data-path`](../Reference/Pantheon-CLI-Syntax.md#data-path) option.
* Genesis file as for Node-1.  

### 5. 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: 

```bash tab="MacOS"
pantheon --data-path=data --genesis-file=../privateNetworkGenesis.json --bootnodes=<Node-1 Enode URL> --p2p-port=30305      
```

```bash tab="Windows"
pantheon --data-path=data --genesis-file=..\privateNetworkGenesis.json --bootnodes=<Node-1 Enode URL> --p2p-port=30305      
```

The command line specifies: 

 * Different port to Node-1 and Node-2 for P2P peer discovery.
 * Data directory for Node-3 using the [`--data-path`](../Reference/Pantheon-CLI-Syntax.md#data-path) option.
 * Bootnode and genesis file as for Node-2. 

### 6. Confirm Private Network is Working 

Start another terminal, use curl to call the JSON-RPC API [`net_peerCount`](../Reference/JSON-RPC-API-Methods.md#net_peercount) method and confirm the nodes are functioning as peers: 

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

The result confirms Node-1 (the node running the JSON-RPC service) has two peers (Node-2 and Node-3):
```json
{
  "jsonrpc" : "2.0",
  "id" : 1,
  "result" : "0x2"
}
```

## Next Steps 

Import accounts to MetaMask and send transactions as described in the [Private Network Quickstart Tutorial](Private-Network-Quickstart.md#creating-a-transaction-using-metamask)

!!! info 
    Pantheon does not implement [private key management](../Using-Pantheon/Account-Management.md).
    
Send transactions using `eth_sendRawTransaction` to [send ether or, deploy or invoke contracts](../Using-Pantheon/Transactions/Transactions.md).

Use the [JSON-RPC API](../JSON-RPC-API/Using-JSON-RPC-API.md). 

Start a node with the [`--rpc-ws-enabled`](../Reference/Pantheon-CLI-Syntax.md#rpc-ws-enabled) option and use the [RPC Pub/Sub API](../Using-Pantheon/RPC-PubSub.md).       

## Stop Nodes

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

!!!tip
    To restart the private network in the future, start from [3. Start First Node as Bootnode](#3-start-first-node-as-bootnode).