Setting up a private Ethereum blockchain with two nodes

Setting up a private Ethereum blockchain with two nodes (or more) and VmWare [FOR TESTING PURPOSES ONLY]

By Eng. Hectór Ugarte

24.03.2016

1. Prerequisites  VmWare Workstation (mine: VMware Workstation 12 Pro).  Ubuntu iso (mine: Ubuntu 15.10) 2. Procedure. A. Create two virtual machines on VmWare, running Ubuntu. Recommended specifications:

B. Set both virtual machines on the same network, for example:

C. Install Geth on both nodes: sudo apt-get install software-properties-common sudo add-apt-repository -y ppa:ethereum/ethereum sudo apt-get update sudo apt-get install ethereum

1 - Setting up a private Ethereum blockchain with two nodes (or more) and VmWare

D. Create a new folder on both virtual machines, called it “Ethereum”, and inside that folder another one, called it “datadir” E. Create a new file inside Ethereum folder, called it “genesis.json” with the next content: { "nonce": "0xdeadbeefdeadbeef", "timestamp": "0x0", "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000", "extraData": "0x0", "gasLimit": "0x8000000", "difficulty": "0x400", "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000", "coinbase": "0x3333333333333333333333333333333333333333", "alloc": { } } F. Now start the geth client on both nodes. geth --genesis --datadir --networkid 12344321 --nodiscover --maxpeers 1 console Where: 1. Use genesis.json as the genesis block. 2. Use datadir folder to put your all the necessary data about the private 3. Use a network id other than ‘1’ to ensure we can’t talk to nodes from the main network – “connections between nodes are valid only if peers have identical protocol version and network id” 4. Disable peer discovery 5. Set a maximum of 1 peers (or more if you want to use more peers) 6. Starts geth in console mode so you can interact with your new blockchain / node For example: sudo geth --genesis="/home/hedugaro/Ethereum/genesis.json" -datadir="/home/hedugaro/Ethereum/datadir" --networkid 12344321 -nodiscover --maxpeers 1 console G. Create Accounts Once geth is up and you get a console, create your own account with the following command:


>personal.newAccount("mypass"); Where “mypass” is your desired password. You get as answer for example: '0xd47eaceb073dc03e3330b4747b1224f146f8d6e7' Repeat this on the other nodes. H. Connect the 2 Nodes as Peers First, find the enode of the first node with the next command: admin.nodeInfo.enode You get as answer: "enode://4e0312fb3eae8b59048afb1a53a3cd4a157db1fb2c8b7175176ffa932e41c2 2c60dd5f7540bbfb7d25b4c443116895360064fe4415734d3da621b29b0a7b6b6e@[::] :30303?discport=0" Instead of [::] , add your ip address to that string, for example: (you can get your ip address with ifconfig command) "enode://4e0312fb3eae8b59048afb1a53a3cd4a157db1fb2c8b7175176ffa932e41c2 2c60dd5f7540bbfb7d25b4c443116895360064fe4415734d3da621b29b0a7b6b6e@172. 16.1.104:30303?discport=0" On the second node, add node one as a peer with the following command: >admin.addPeer("enode://4e0312fb3eae8b59048afb1a53a3cd4a157db1fb2c8b717 5176ffa932e41c22c60dd5f7540bbfb7d25b4c443116895360064fe4415734d3da621b2 [email protected]:30303?discport=0") I.

Check if everything went ok, with the command:

web3.net.peerCount You should get as response 1 Now the two nodes are configured on a private blockchain. At least one node should be mining. J.

To do that:

miner.setEtherbase(eth.accounts[0]) and miner.start() K. It will take around 10 minutes to produce the DAG file (needed for mining) (Dagger-Hashimoto)


L. After the DAG is produced, the mining procedure will start. You can check that the minner account balance is increasing, calling the function getbalance, for example: web3.eth.getBalance("0xc6acbafc19fbcb5ee3af6bf471c0c510e3d9d0c2")

Useful information: Website: https://www.ethereum.org/ Blog: http://blog.ethereum.org/ Homestead documentation: http://www.ethdocs.org/ Reedit: http://www.reddit.com/r/ethereum Forum: https://forum.ethereum.org/


Setting up a private Ethereum blockchain with two nodes

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