firewallbust.js

var dgram = require('dgram')
var client = dgram.createSocket("udp4");
var serverip = process.argv[2];
var serverPort = 19132;
client.bind(19132);

client.on("message", function (msg, rinfo)
{
  console.log("Received packet " + msg + " from " + rinfo.ip);
});

client.on("listening", function()
{
  setInterval(function(){
    var d=new Date();
    var t=d.getTime();
    client.send(t, 0, t.length, serverPort, serverip);
    console.log("Sent packet " + t + " to " + serverip)
},1000);
})

gistfile1.rb

# From
# http://www.rubyinside.com/skype-style-firewall-busting-with-ruby-and-udp-399.html

require 'socket'

remote_host = ARGV.first

# Punches hole in firewall
punch = UDPSocket.new
punch.bind('', 6311)
punch.send('', 0, remote_host, 6311)
punch.close

# Bind for receiving
udp_in = UDPSocket.new
udp_in.bind('0.0.0.0', 6311)
puts "Binding to local port 6311"

loop do
  # Receive data or time out after 5 seconds
  if IO.select([udp_in], nil, nil, rand(4))
        data = udp_in.recvfrom(1024)
        remote_port = data[1][1]
        remote_addr = data[1][3]
        puts "Response from #{remote_addr}:#{remote_port} is #{data[0]}"
  else
        puts "Sending a little something.."
        udp_in.send(Time.now.to_s, 0, remote_host, 6311)
  end
end

hi.js

var dgram = require("dgram");
var server = dgram.createSocket("udp4");
server.on("message", function (msg, rinfo) {
console.log("server got: " + msg + " from " +
	rinfo.address + ":" + rinfo.port);
});
server.on("listening", function () {
	var address = server.address();
	console.log("server listening " +
	address.address + ":" + address.port);
});
server.bind(43278);