Socket.IO Authentication Tutorial (Server and Client) - http://wlkns.co/?p=52

app.js

/* app.js
 *
 * This code is the client to connect to the Socket.IO server run in the clients browser */

jQuery(document).ready(function(){
  /* Connect the socket */
  socket = io.connect('http://localhost:8080', {
    /* Pass the authentication token as a URL parameter */
    query: $.param({token: 'i271az2Z0PMjhd6w0rX019g0iS7c2q4R'})
    /* My application is more complicated, so I use jQuery's .param utility to convert the Object to an URL string e.g. 'token=abc&etc=cde' */
  });

  console.log("Connecting...");

  /* Bind all the most common events for debugging... we use "message" in server.js, so I put that first */
  var events = ['message', 'connect', 'connecting', 'disconnect', 'connect_failed', 'connect_timeout', 'connect_error', 'error', 'reconnect_failed', 'reconnect', 'reconnecting', 'disconnect'];
  for ( var i in events )
  {
    event_name = events[i];
    
    /* Output the event and any data to the  browser console */
    socket.on(event_name, function( data ) {
      console.log(event_name, data);
    });
  }

});

server.js

// server.js

// The Node JS Socket.IO Server

// Launch the server, I've used express as most people use Socket.IO on Express
var app = require('express').createServer(),
    io = require('socket.io').listen(app);

server.listen(8080);

// We will use token based authentication, these could be session ID's or username/passwords...
var tokens = [
  'i271az2Z0PMjhd6w0rX019g0iS7c2q4R',
  'oWD4sh1eU2Yhn95C05t2YKrKMVWoAFAk'
];

// Socket.IO Connections first get passed through Authorization (if it exists)
io.set('authorization', function(req, callback) {

  // Some basic validation to make sure a token was passed
  if ( req.query.token === undefined || req.query.token.length === 0 )
  {
    return false;
  }

  // Loop through the valid tokens, to validate the token passed
  var validated = false;
  for ( var key in tokens )
  {
    if ( key == req.query.token )
    {
      validated = true;
      break;
    }
  }

  // If valid, continue to callback the next function
  if ( validated )
  {
    return callback(null, true);
  }
  else
  {
    return false;
  }
});

// Everything else Socket.IO works normally...
io.sockets.on('connection', function (socket) {
  console.log('Client connected from: ' + socket.handshake.address);
  
  // Send the server date every 30 seconds, just to validate the connection
  setInterval(function(){
    io.sockets.emit('message', (new Date()));
  }, 30000);

  socket.on('disconnect', function () {
    console.log('Client disconnected.');
  });
});