eth 常用networkid 1，3 ，4 ，42
以太坊常用net work id，一般配合MetaMask 使用的id 有
| ID | name |
|---|---|
| 1 | main network |
| 3 | Ropsten |
| 4 | Rinkeby |
| 42 | Kovan |
0: Olympic, Ethereum public pre-release testnet
1: Frontier, Homestead, Metropolis, the Ethereum public main network
1: Classic, the (un)forked public Ethereum Classic main network, chain ID 61
1: Expanse, an alternative Ethereum implementation, chain ID 2
2: Morden, the public Ethereum testnet, now Ethereum Classic testnet
3: Ropsten, the public cross-client Ethereum testnet
4: Rinkeby, the public Geth PoA testnet
8: Ubiq, the public Gubiq main network with flux difficulty chain ID 8
42: Kovan, the public Parity PoA testnet
77: Sokol, the public POA Network testnet
99: Core, the public POA Network main network
100: xDai, the public MakerDAO/POA Network main network
401697: Tobalaba, the public Energy Web Foundation testnet
7762959: Musicoin, the music blockchain
61717561: Aquachain, ASIC resistant chain
[Other]: Could indicate that your connected to a local development test network.