How to generate the correct go-ethereum bootnode when creating a private blockchain

Question

I am trying to setup a private ethereum chain and connect two peers to it. I followed this tutorial on github. One of the two peers ran from a windows 10 geth client. The other ran from a Ubuntu geth client (Ubuntu itself ran on Virtual Box).

I started off by creating a genesis block (genesis.json) on the windows client:

{

"config": {

"chainId": 19,

"homesteadBlock": 0,

"eip155Block": 0,

"eip158Block": 0

},

"difficulty": "15",

"gasLimit": "2100000",

"alloc": {}

}

Then I ran in cmd :

geth --datadir path/to/data init genesis.json

After that, I created the bootnode：

bootnode --genkey = boot.key

and

bootnode --nodekey = node.key

I then received

self=enode://6b2700c843fb78732706a2b687ce751a2fbaf7d9034f455f5037af68f1ca0c1a52824cd178f17bc994af9c489d9e3ed0795900ae0efe4eacafb1e8653dc3eb6e@[myip]:30301

My understanding is that this enode will point the future peers to the genesis block and other peers. Here is the problem. I am able to ping myip,yet

telnet myip 30301

is unsuccessful. I suspect that i did not use the correct Ip address. I tried using the ipv4 address found from ipconfig, as well as my ipv4 address that I looked up online (probably given by the service proider) with no avail.

Answer 1

If you can't telnet then there is something wrong with your networking. Either your virtual network connection between hosts is the problem or there is a firewall blocking connections.

If you are just getting started then I'd keep things really simple first of all and:

• Use standard geth nodes
• Run your nodes on one virtual machine on different ports

e.g. initialise your geth nodes like this:

ethuser@host01:~$ mkdir test1
ethuser@host01:~$ cd test1
ethuser@host01:~/test1$ mkdir nodeA
ethuser@host01:~/test1$ mkdir nodeB
ethuser@host01:~/test1$ <use your favourite editor to create a genesis.json file in this directory>
ethuser@host01:~/test1$ geth --datadir nodeA init genesis.json
WARN [08-04|10:41:41] No etherbase set and no accounts found as default 
INFO [08-04|10:41:41] Allocated cache and file handles         database=/home/ethuser/test1/nodeA/geth/chaindata cache=16 handles=16
INFO [08-04|10:41:41] Writing custom genesis block 
INFO [08-04|10:41:41] Successfully wrote genesis state         database=chaindata                                hash=dd3f8d…707d0d
INFO [08-04|10:41:41] Allocated cache and file handles         database=/home/ethuser/test1/nodeA/geth/lightchaindata cache=16 handles=16
INFO [08-04|10:41:41] Writing custom genesis block 
INFO [08-04|10:41:41] Successfully wrote genesis state         database=lightchaindata                                hash=dd3f8d…707d0d
ethuser@host01:~/test1$ geth --datadir nodeB init genesis.json
WARN [08-04|10:41:52] No etherbase set and no accounts found as default 
INFO [08-04|10:41:52] Allocated cache and file handles         database=/home/ethuser/test1/nodeB/geth/chaindata cache=16 handles=16
INFO [08-04|10:41:52] Writing custom genesis block 
INFO [08-04|10:41:52] Successfully wrote genesis state         database=chaindata                                hash=dd3f8d…707d0d
INFO [08-04|10:41:52] Allocated cache and file handles         database=/home/ethuser/test1/nodeB/geth/lightchaindata cache=16 handles=16
INFO [08-04|10:41:52] Writing custom genesis block 
INFO [08-04|10:41:52] Successfully wrote genesis state         database=lightchaindata                                hash=dd3f8d…707d0d
ethuser@host01:~/test1$ 

Then launch your first geth node like this

ethuser@host01:~/test1$ geth --datadir nodeA --networkid 1234567 console
WARN [08-04|10:42:22] No etherbase set and no accounts found as default 
INFO [08-04|10:42:22] Starting peer-to-peer node               instance=Geth/v1.6.7-stable-ab5646c5/linux-amd64/go1.8.1
INFO [08-04|10:42:22] Allocated cache and file handles         database=/home/ethuser/test1/nodeA/geth/chaindata cache=128 handles=1024
WARN [08-04|10:42:22] Upgrading chain database to use sequential keys 
INFO [08-04|10:42:22] Initialised chain configuration          config="{ChainID: 1907 Homestead: 0 DAO: <nil> DAOSupport: false EIP150: <nil> EIP155: 0 EIP158: 0 Metropolis: <nil> Engine: unknown}"
INFO [08-04|10:42:22] Disk storage enabled for ethash caches   dir=/home/ethuser/test1/nodeA/geth/ethash count=3
INFO [08-04|10:42:22] Disk storage enabled for ethash DAGs     dir=/home/ethuser/.ethash                 count=2
WARN [08-04|10:42:22] Upgrading db log bloom bins 
INFO [08-04|10:42:22] Bloom-bin upgrade completed              elapsed=252.683µs
INFO [08-04|10:42:22] Initialising Ethereum protocol           versions="[63 62]" network=1234567
INFO [08-04|10:42:22] Database conversion successful 
INFO [08-04|10:42:22] Loaded most recent local header          number=0 hash=dd3f8d…707d0d td=40
INFO [08-04|10:42:22] Loaded most recent local full block      number=0 hash=dd3f8d…707d0d td=40
INFO [08-04|10:42:22] Loaded most recent local fast block      number=0 hash=dd3f8d…707d0d td=40
INFO [08-04|10:42:22] Starting P2P networking 
INFO [08-04|10:42:22] UDP listener up                          self=enode://9ce583f7e1905b23217cd2a92894291c6d8f5ce7a29e85fdeaf48b3ab065c6d5b6cce4f064fdaf26f41d2354bf0a203438563f6ffdba73cec3b8692f6f850817@[::]:30303
INFO [08-04|10:42:22] RLPx listener up                         self=enode://9ce583f7e1905b23217cd2a92894291c6d8f5ce7a29e85fdeaf48b3ab065c6d5b6cce4f064fdaf26f41d2354bf0a203438563f6ffdba73cec3b8692f6f850817@[::]:30303
INFO [08-04|10:42:22] IPC endpoint opened: /home/ethuser/test1/nodeA/geth.ipc 
Welcome to the Geth JavaScript console!

instance: Geth/v1.6.7-stable-ab5646c5/linux-amd64/go1.8.1
 modules: admin:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0

> 

And then start up your second node. In my case I needed to use ethuser@host01:~/test1$ geth --datadir nodeB --port 30304 --networkid 1234567 --bootnodes enode://9ce583f7e1905b23217cd2a92894291c6d8f5ce7a29e85fdeaf48b3ab065c6d5b6cce4f064fdaf26f41d2354bf0a203438563f6ffdba73cec3b8692f6f850817@127.0.0.1:30303

Wait a few moments to give the nodes a chance to connect and then double check in your console that admin.peers returns some more info, e.g.

> admin.peers
[{
    caps: ["eth/63"],
    id: "9ce583f7e1905b23217cd2a92894291c6d8f5ce7a29e85fdeaf48b3ab065c6d5b6cce4f064fdaf26f41d2354bf0a203438563f6ffdba73cec3b8692f6f850817",
    name: "Geth/v1.6.7-stable-ab5646c5/linux-amd64/go1.8.1",
    network: {
      localAddress: "127.0.0.1:41900",
      remoteAddress: "127.0.0.1:30303"
    },
    protocols: {
      eth: {
        difficulty: 40,
        head: "0xdd3f8d61f38ebc195a6c9b0e5888e7e035f31ecd92e4427fb01176b984707d0d",
        version: 63
      }
    }
}]
> 

I've left out creating accounts etc as you don't specifically ask it but if you're interested here are some more of my own newbie experiences: https://alanbuxton.wordpress.com/2017/07/19/first-steps-with-ethereum-private-networks-and-smart-contracts-on-ubuntu-16-04/