Error: Invalid JSON RPC response: undefined from node web3.js app

Question

I'm getting Error: Invalid JSON RPC response: undefined from my node.js application when it tries to execute a function. My steps:

1. ethereum wallet 0.5.1 to deploy a contract to the testnet.

2. start the geth client version 1.3.3:

   $ geth --rpc --rpcaddr "0.0.0.0" --rpcapi "eth,web3" --rpcport 8546 --networkid 5678 attach
   

(I can run web3.eth.accounts from within the geth console and it returns my locally created accounts)

3. used npm to install web3 version 0.15.3

4. from within the node shell:

   > var Web3 = require('web3')
   > web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8546"))
   > web3.version.api
   '0.15.3'
   > web3.eth.accounts
   Error: Invalid JSON RPC response: undefined
   at Object.module.exports.InvalidResponse (/Users/jbowkett/node_modules/web3/lib/web3/errors.js:35:16)
   at HttpProvider.send (/Users/jbowkett/node_modules/web3/lib/web3/httpprovider.js:87:22)
   at RequestManager.send (/Users/jbowkett/node_modules/web3/lib/web3/requestmanager.js:58:32)
   at Eth.get [as accounts] (/Users/jbowkett/node_modules/web3/lib/web3/property.js:107:62)
   at repl:1:9
   at REPLServer.defaultEval (repl.js:252:27)
   at bound (domain.js:287:14)
   at REPLServer.runBound [as eval] (domain.js:300:12)
   at REPLServer.<anonymous> (repl.js:417:12)
   at emitOne (events.js:82:20)
   

Also : $ telnet localhost 8546 yields no connection

Answer 1

from the geth console:

admin.startRPC("127.0.0.1", 8545, "*", "web3,db,net,eth")

then I was able to reconnect in node, and list the accounts. (unsurprisingly, telnet responded on this port too after starting RPC from within geth)

Taken from here:

web3 methods not implemented