Cannot connect to ethereum Ropsten testnet node

Question

I installed Ropsten (revival) testnet on an Ubuntu server, Then I start my testnet node:

geth --testnet

I can connect to my node via

geth attach ipc:/home/myusername/.ethereum/testnet/geth.ipc

and I get this info from my node instance:

> admin.nodeInfo
{
  enode: "enode://03aa54...0689be3@24.230.213.120:30303",
  id: "03aa54b894aec...a49d8490689be3",
  ip: "www.xxx.yyy.zzz",
  listenAddr: "[::]:30303",
  name: "Geth/v1.6.7-stable-ab5646c5/linux-amd64/go1.8.1",
  ports: {
    discovery: 30303,
    listener: 30303
  },
  protocols: {
    eth: {
      difficulty: 1621387497788667,
      genesis: "0x41941023680923e0fe4d74a34bdac8141f2540e3ae90623718e47d66d1ca4a2d",
      head: "0x84e8e85cdd7a5fa79d26b9fa89cd850be23b13d2079208e052eceb06c436654b",
      network: 3
    }
  }
}

But I cannot connect to the testnet node from my nodejs script:

Web3 = require("web3");
web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:30303"));
console.log(web3.isConnected());

always return false ! Any advice ?

Answer 1

The port 30303 is used by the client (TCP as listener and UDP for discovery) to communicate in the peer to peer protocol.

For Web3, you must use the JSON-RPC port (by default 8545) which can be enabled with the following parameter --rpc

Command:

geth --testnet --rpc --rpcapi "eth,net,web3" --rpccorsdomain '*' --rpcaddr 127.0.0.1 --rpcport 8545 

Then you can try to run:

Web3 = require("web3");
web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
console.log(web3.isConnected());

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