Node.js UDP

client.js

var udp = require("dgram");

var socket = udp.createSocket("udp4");

var msg = new Buffer("ping");

socket.send(msg, 0, msg.length, 8232, "localhost");

socket.on("message", function(msg, info) {
  var res = new Buffer("client -> " + info.address + ":" + info.port);
  console.log(msg.toString());
  setTimeout(function() {
    socket.send(res, 0, res.length, info.port, info.address);
  }, 600);
});

run.sh

#!/bin/bash

node server.js &
sleep 1
node client.js

server.js

var udp = require("dgram");

var socket = udp.createSocket("udp4");

socket.bind(8232);
console.log("listening on port 8232");

socket.on("message", function(msg, info) {
  var res = new Buffer("server -> " + info.address + ":" + info.port);
  console.log(msg.toString());
  socket.send(res, 0, res.length, info.port, info.address);
});