Blockchain development (i) building a private chain environment based on Ethereum (block chain)

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Blockchain Development (i) building a private chain environment based on the Ethereum

Lihe 2016.07.08

Through the methods described in this article and the script, we can quickly set up their own private chain for blockchain development testing, this article is based on the Ethereum technology to build, divided into two parts, one is the Ubuntu under the construction method, the other is the Windwos under the building method, about the basic knowledge of ethereum related, can look at my original published some articles, the address is as follows: Http://

I. Install Geth client under Ubuntu

The reason for using Ubuntu is that the official Ethereum support for Ubuntu is very good, and it is easiest to install on each Linux system.

Geth Official Installation Guide:


Go to the Ubuntu command line and execute the following command

sudo apt-get update

sudo apt-get Installsoftware-properties-common

sudo add-apt-repository-yppa:ethereum/ethereum

sudo add-apt-repository-yppa:ethereum/ethereum-dev

sudo apt-get update

sudo apt-get install Ethereum

The installation of the Ethereum client, including Geth,bootnode, EVM, Disasm, Rlpdump,ethtest, was completed after the system network was implemented.

At this point, if you enter the Geth command, you will be prompted to start the Ethereum start screen

Second, install the Windows Geth client

Windows must be 64-bit system, download the compiled Win64 client from the official website, unzip to run, download the address as follows:

After downloading, there is only one Geth.exe file.

Install the image client mist, still download the compiled client from the official address, download the address:

After the download is uncompressed, the Ethereum-wallet is the Ethereum graphical interface.

Iii. preparing for the creation of a block document

Configure their own creation block is to distinguish the public chain, the same network, the creation of the block must be the same, or can not be connected, this method in Windows and Ubuntu under General.

New file Piccgenesis.json, enter the following and save


"Nonce": "0x0000000000000042",

"Mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",

"Difficulty": "0x4000",

"Alloc": {},

"Coinbase": "0x0000000000000000000000000000000000000000",

"Timestamp": "0x00",

"Parenthash": "0x0000000000000000000000000000000000000000000000000000000000000000",

"Extradata": "PICC genesisblock",

"Gaslimit": "0xFFFFFFFF"


Explain the effects of each parameter:


A hash that is generated by a portion of the previous block in conjunction with a nonce for mining. Note that he and the nonce settings need to meet Ethereum's yellow paper, 4.3.4. Block Header Validity, (44) The conditions described in the chapter:


A nonce is a 64-bit random number used to mine mining, noting that his and mixhash settings need to meet the Ethereum yellow paper, 4.3.4. Block Header Validity, (44) The conditions described in the chapter.


The difficulty of setting the current block, if the difficulty is too large, the CPU mining is difficult, here set a small difficulty


The number of etheric coins used to pre-provision accounts and account numbers, because the private chain mining is easier, so we do not need to pre-set the account of the currency, when needed to create their own.


The miner's account, just fill it out.


Set the time stamp of the Genesis block


The hash value of the previous chunk, because it is a Genesis block, so this value is 0


Additional information, please fill in, can fill in your personal information


This value sets the total consumption limit for gas, which is used to limit the sum of the transaction information that the block can contain, since we are the private chain, so fill the maximum.


Iv. starting a private chain node

Starting Geth can start the Ethereum blockchain, in order to build a private chain, you need to add some parameters at Geth startup, the Geth parameter meaning is as follows:


The name of the blockchain, which is used to mark the current network


Specify the location of the Genesis block file and create the initial block


Sets the location of the current blockchain network data storage


Network Listening port


Initiate RPC communication to deploy and debug smart contracts


Sets the client that allows RPC to be connected, typically DB,ETH,NET,WEB3


Sets the network ID of the current blockchain to distinguish between different networks, which is a number


Start command line mode, you can execute commands in Geth

1. Start the Blockchain node in Ubuntu

Under Ubuntu, first switch to the directory you intend to run, the directory should have a configured Piccgenesis.json file, execute the following command

basepath=$ (CD ' DirName $ '; pwd)

Get the current directory

Geth--datadir "$basepath/chain" Init Piccgenesis.json

Create a data store address and initialize the Genesis block

Geth--identity "Piccetherum"--rpc--rpccorsdomain "*"--datadir "$basepath/chain"--port "30303"--rpcapi "db,eth,net, WEB3 "--networkid 95518 Console

After starting the interface as follows, the cursor rests on the last command line and can execute the ethereum command.

I0707 00:45:43.680087 ethdb/database.go:82]alloted 128MB Cache and 1024x768 file handles to/home/lihe/desktop/chain/chaindata

I0707 00:45:43.726008ethdb/database.go:169] closed db:/home/lihe/Desktop/chain/chaindata

I0707 00:45:43.728913 ethdb/database.go:82]alloted 128MB Cache and 1024x768 file handles to/home/lihe/desktop/chain/chaindata

I0707 00:45:43.908795 ethdb/database.go:82]alloted 16MB cache and file handles to/home/lihe/desktop/chain/dapp

I0707 00:45:43.969506 core/genesis.go:92]genesis block already in chain. Writing Canonical number

I0707 00:45:43.980337 Eth/backend.go:274]successfully wrote custom Genesis block : 6e92f8b23bcdfdf34dc813cfaf1d84b71beac80530506b5d63a2df10fe23a660

I0707 00:45:43.980618 eth/backend.go:184]protocol Versions: [[+], Network id:95518

I0707 00:45:43.981567core/blockchain.go:204] Last header: #81 [6193c4b0 ...] td=10836704

I0707 00:45:43.981645core/blockchain.go:205] Last block: #81 [6193c4b0 ...] td=10836704

I0707 00:45:43.981677core/blockchain.go:206] Fast block: #81 [6193c4b0 ...] td=10836704

I0707 00:45:43.985253 p2p/server.go:313]starting Server

I0707 00:45:45.834488p2p/discover/udp.go:217] listening,enode:// 134881790e54c803955715e3661c27f91caaf499be813e29c9f986e2eac62d47e02b13a8e51776c1caea554655614ed26ce0185d84e626da7ac48a83a 60113ff@[::]:30303

I0707 00:45:45.835853 node/node.go:366]http Endpoint opened:http://localhost:8545

I0707 00:45:45.848008 p2p/server.go:556]listening on [::]:30303

I0707 00:45:45.849731 node/node.go:296] Ipcendpoint opened:/home/lihe/Desktop/CHAIN/GETH.IPC

Welcome to the Geth JavaScript console!



At block:81 (Tue, 21:02:25CST)


modules:admin:1.0 debug:1.0 eth:1.0 miner:1.0net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0


You can see listening on [::]:30303 and welcome to the Geth JavaScript console! tips that indicate that the success has been started

Note: If you want to use Ubuntu as a permanent blockchain node, the Geth startup parameter console must be removed when using the Nohup command, or Geth will stop automatically.

2. Start the Blockchain node in Windows

Go to the directory under Windows Geth, place the configured Piccgenesis.json file, and execute the following command:

Geth--datadir "%cd%\chain" Init Piccgenesis.json

Create a data store address and initialize the Genesis block

Geth--identity "Piccetherum"--rpc--rpccorsdomain "*"--datadir "%cd%\chain"--port "30303"--rpcapi "DB,ETH,NET,WEB3"- -networkid 95518 Console

When you see listening on [::]:30303 and welcome to the Geth JavaScript console!, instructions have been started successfully

v. Create an account using a node

After the boot node succeeds, it will enter the command line mode of Geth and enter the following command

Personal.newaccount ()

You will be prompted to enter your account password and confirm that a new generated account will be displayed at the end.

Vi. start the private chain graphics node under Windows

First follow the above steps to start Geth and create an account, and then extract Ethereum-wallet, run Ethereum-wallet.exe, that is, start successfully, if the blockchain is normal, the upper right corner of the display "Private-net", click "LAUNCH Application "into the graphical interface.


Vii. connecting other nodes

First you need to know your node information, enter the command in the Geth command line interface, note the case


The system will display

Enode: "enode:// 1e3c1727cd3bee9f25edeb5dbb3b880e03e41f8eec99566557f3ee0422734a8fcad17c161aa93d61bdbfb28ed152c143c7eb501db58bc63502a104a84 b62d742@ "


enode:// 1e3c1727cd3bee9f25edeb5dbb3b880e03e41f8eec99566557f3ee0422734a8fcad17c161aa93d61bdbfb28ed152c143c7eb501db58bc63502a104a84 b62d742@

Is the information of their own nodes, pay attention to the "" for your own IP. Send this information to the other nodes and enter them on the command line of the other nodes:

Admin.addpeer (' enode:// 1e3c1727cd3bee9f25edeb5dbb3b880e03e41f8eec99566557f3ee0422734a8fcad17c161aa93d61bdbfb28ed152c143c7eb501db58bc63502a104a84 b62d742@ ')

If added successfully, the input admin.peers will display the newly added node.

Viii. using nodes for mining

In the Geth command line interface, the input Miner.start () is started mining, mining, will not stop brush screen, input miner.stop () stop, no tube brush screen caused by the command is not complete, the command will be executed normally.

In this step, a network of private chains has been formed, which can be extended as the other blockchain, and in the next article I will describe how to write, debug, and deploy smart contracts on a private chain.

Reference article:

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