Network ID and Chain ID

Ethereum networks have a network ID and a chain ID. The network ID defaults to the chain ID specified in the genesis file.

Chain ID in Genesis File

  "config": {
    "ethash": {
     "chainID": 1981

For most networks including MainNet and the public testnets, the network ID and the chain ID are the same and are specified in the genesis file.

The network ID and chain ID are automatically defined by Pantheon when connecting to networks specified using the --network option:

  • MainNet: chain-id 1, network-id 1
  • Rinkeby: chain-id 4, network-id 4
  • Ropsten: chain-id 3, network-id 3
  • Dev: chain-id 2018, network-id 2018

When using the --network=dev or --genesis-file options, you can override the network ID using the --network-id option.