Go Ethereum – How to Find Free Network ID and Chain ID for Private Blockchain Network

Private blockchain Everyone is equal, and can mine the transactions. Basically you need to share your genesis block with the other party and once they initialize their chain, you have to add their enode addrees as peer.

Permissioned blockchain Permission is built into your blockchain client, where you can decide based on the other party cryptographic information what access will they have. Monax, Hyperledger fabric, jpmorgan quorum are some examples of permissioned chains.. Based on your comment , you are trying to create a private blockchain.

1. Initialize your blockchain in Node A as, geth --datadir geth_data init genesis.json Note : Alloc section should be empty in your genesis block This will initialize your chain in your data directory.
2. Now start the geth again , this time without the init geth --datadir geth_data --port 54259 console

Note, Once geth starts in console mode, enable personal API and create your 1st account, seed your account with some ether in your genesis alloc block. For adding a peer via console you should enable admin API.

3. Get your enode address of Node A with the command

   admin.nodeInfo.enode
   "enode://fc542dd3209dd73da7b4282990e1ad39ad9d61d772bc844d416d58ae97bdbb02aa40f65 5f7565276dab552e9cc363376a6e76ebbf08f7f665b9b9d4a8b286d18@[::]:54259"

replace the [::] with your IP of Node A. Now you are ready to connect to another Node B.

4.In Node B,keep your genesis.json , your A node's enode address handy. Initialize the chain with the genesis block that you have from A.

Once initialized, you can check in either machines if they have any peers

admin.peers []

5. Then add in Node B, Node A

   admin.addPeer("enode://a979fb575495b8d6db44f750317d0f4622bf4c2aa3365d6af7c284339968eef29b69ad0dce72a4d8db5ebb4968de0e3bec910127f134779fbcb0cb6d3331163c@52.16.188.185:30303") true

Once this is done, the two Nodes now are connected and would receive any contracts or events happening in either A or B.

You can check this by,

admin.peers

6. Please note this linkage between the nodes would only stay until one of the node goes down. To make the linkage permanent- Add the node as a static peer.
7. Create a file static_nodes.json and place it your data directory. Please refer to the links below.

References -

https://github.com/ethereum/go-ethereum/wiki/Connecting-to-the-network How to use static-nodes.json / trusted-nodes.json to prevent connection loss on private network? https://github.com/ethereum/go-ethereum/wiki/Management-APIs