In the following sections I will try to describe things that I had problem to deal with and how I actually managed to accomplish them. It's quite interesting how all tutorials and documentation even is outdated easily. This might get outdated as well but at least I will try to update it as frequently as possible.
Disclaimer: I assume that you have at least installed geth. - there are plenty of places to read and they are quite accurate. Since I'm using Linux Mint 18 which is more or less derivative of Ubuntu - here is a link:
Geth (Go-Ethereum) Installation Guidelines
Basically you will need this at least to experiment initially ( how to mine, how to do transactions and send ether to different accounts and etc.) also to verify your smart contracts logic.
In order not to break something on the main-net (1) which is under ~/.ethereum (at least for linux machines). - create separate folder - i.e. privnet under your home directory.
tek@citadel ~ $ mkdir privnet && cd privnet
This command will create the folder and get you inside of it once the command is executed. In order to be more productive, let's open 3 separate terminals.
It's very important to use the same genesis file for all of the nodes you are about to create
Pick one of the terminal and execute the following command:
tek@citadel ~/privnet $ vim Genesis.json
Copy/Paste the code below and save. This is sample Genesis file.
{
"nonce": "0x00006d6f7264656e",
"difficulty": "0x20000",
"mixhash": "0x00000000000000000000000000000000000000647572616c65787365646c6578",
"coinbase": "0x0000000000000000000000000000000000000000",
"timestamp": "0x00",
"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"extraData": "0x",
"gasLimit": "0x2FEFD8",
"alloc": {
"0000000000000000000000000000000000000001": {
"balance": "1"
},
"0000000000000000000000000000000000000002": {
"balance": "1"
},
"0000000000000000000000000000000000000003": {
"balance": "1"
},
"0000000000000000000000000000000000000004": {
"balance": "1"
},
"102e61f5d8f9bc71d0ad4a084df4e65e05ce0e1c": {
"balance": "1606938044258990275541962092341162602522202993782792835301376"
}
}
}
In the very same terminal where you created the Genesis file, create a folder for the first node.
tek@citadel ~/privnet $ mkdir node1
This will be used as a place where to store all information of node one.
Let's create the chain and put the first block.
tek@citadel ~/privnet $ geth --datadir node1/ init Genesis.json
Note: Very important to specify the datadir because otherwise you will break the main-net because commands of this type apply on ~/.ethereum where all the data of main-net is stored.
Another note: Also important to specify the flag (datadir) before init Genesis.json otherwise an error will be thrown.
Let's light up the first node.
tek@citadel ~/privnet $ geth --identity "Node One" --rpc --rpcport "8080" --rpccorsdomain "*" --rpcapi "eth, net, web3" --datadir node1/ --port "30300" --maxpeers 3 --networkid 777 --vmdebug
What the flags are you can easily read the documentation or simply execute:
geth --help
The ones to concentrate are:
- --datadir - Well as mentioned before, this one is a MUST in order not to break something
- --identity - Identifier of your node. Easy to track on which node you are under console.
- --rpcport - This port with conjuction of your ip address (localhost) form the address for HTTP-RPC communication. When create instance of Web3 you have to provide this whole address so that the WebApp can communicate with the node.
- --port - This is used for the communication between different nodes. It's part of the ENODE Address.
- --networkid - Unique ID of the network. All three nodes MUST share same networkId.
Once you light up the node you must see something similar.
I0226 21:21:45.075816 cmd/utils/flags.go:613] WARNING: No etherbase set and no accounts found as default
I0226 21:21:45.075918 ethdb/database.go:83] Allotted 128MB cache and 1024 file handles to /home/tek/privnet/node1/geth/chaindata
I0226 21:21:45.100140 ethdb/database.go:176] closed db:/home/tek/privnet/node1/geth/chaindata
I0226 21:21:45.100896 node/node.go:176] instance: Geth/Node One/v1.5.9-stable-a07539fb/linux/go1.7.3
I0226 21:21:45.100921 ethdb/database.go:83] Allotted 128MB cache and 1024 file handles to /home/tek/privnet/node1/geth/chaindata
I0226 21:21:45.118910 eth/db_upgrade.go:346] upgrading db log bloom bins
I0226 21:21:45.119063 eth/db_upgrade.go:354] upgrade completed in 155.886µs
I0226 21:21:45.119096 eth/backend.go:187] Protocol Versions: [63 62], Network Id: 777
I0226 21:21:45.119321 eth/backend.go:215] Chain config: {ChainID: 0 Homestead: <nil> DAO: <nil> DAOSupport: false EIP150: <nil> EIP155: <nil> EIP158: <nil>}
I0226 21:21:45.119727 core/blockchain.go:219] Last header: #0 [c31c0728…] TD=131072
I0226 21:21:45.119748 core/blockchain.go:220] Last block: #0 [c31c0728…] TD=131072
I0226 21:21:45.119759 core/blockchain.go:221] Fast block: #0 [c31c0728…] TD=131072
I0226 21:21:45.120592 p2p/server.go:340] Starting Server
I0226 21:21:47.241397 p2p/discover/udp.go:227] Listening, enode://e16126c135a468767c961c9945d2a21e91be296c89ce391b7da9a92de2c9b0d4f3a7965cfa60dc149656eb3028e66c7fa156bbbd9c53e37e79a3c3540cc1e5f7@[::]:30300
I0226 21:21:47.241609 p2p/server.go:608] Listening on [::]:30300
I0226 21:21:47.244048 node/node.go:341] IPC endpoint opened: /home/tek/privnet/node1/geth.ipc
I0226 21:21:47.244588 node/node.go:411] HTTP endpoint opened: http://localhost:8080
^CI0226 21:22:02.781104 cmd/utils/cmd.go:82] Got interrupt, shutting down...
I0226 21:22:02.781202 node/node.go:427] HTTP endpoint closed: http://localhost:8080
I0226 21:22:02.781283 node/node.go:373] IPC endpoint closed: /home/tek/privnet/node1/geth.ipc
I0226 21:22:02.781306 core/blockchain.go:589] Chain manager stopped
I0226 21:22:02.781321 eth/handler.go:230] Stopping ethereum protocol handler...
I0226 21:22:02.781348 eth/handler.go:251] Ethereum protocol handler stopped
I0226 21:22:02.781411 core/tx_pool.go:196] Transaction pool stopped
I0226 21:22:02.781463 eth/backend.go:519] Automatic pregeneration of ethash DAG OFF (ethash dir: /home/tek/.ethash)
I0226 21:22:02.781646 ethdb/database.go:176] closed db:/home/tek/privnet/node1/geth/chaindata
Couple important parameteres to notice!
- enode://e16126c135a468767c961c9945d2a21e91be296c89ce391b7da9a92de2c9b0d4f3a7965cfa60dc149656eb3028e66c7fa156bbbd9c53e37e79a3c3540cc1e5f7@[::]:30300 - this is the unique address of your node instance. It is used to add nodes as peers to a given node. [::] - means it's deployed on localhost.
- HTTP endpoint opened: http://localhost:8080 - this is the address to which you connect the Web3. By Web3 I mean when you include web3.js in the browser and you want to develop application. If you pay attention you will see that web3.js is used in the geth console as well.
- IPC endpoint closed: /home/tek/privnet/node1/geth.ipc - used to attach console to this node.
geth attach /home/tek/privnet/node1/geth.ipcfor example.
Note: As mentioned before, when no specification is applied, geth command operates over ~/.ethereum . That means that if you invoke geth attach it will attach to /home/tek/.ethereum/geth.ipc.